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Integrating multi-directional connectivity requirements in systematic conservation planning in freshwater systems
Diversity and Distributions
Abstract
Aim Recent efforts to apply the principles of systematic conservation planning to freshwater ecosystems have focused on the special connected nature of these systems as a way to ensure adequacy (long-term maintenance of biodiversity). Connectivity is important in maintaining biodiversity and key ecological processes in freshwater environments and is of special relevance for conservation planning in these systems. However, freshwater conservation planning has focused on longitudinal connectivity requirements within riverine ecosystems, while other habitats, such as floodplain wetlands or lakes and connections among them, have been overlooked. Here, we address this gap by incorporating a new component of connectivity in addition to the traditional longitudinal measure.
Location Northern Australia.
Methods We integrate lateral connections between freshwater areas (e.g. lakes and wetlands) that are not directly connected by the river network and the longitudinal upstream–downstream connections. We demonstrate how this can be used to incorporate ecological requirements of some water-dependent taxa that can move across drainage divides, such as waterbirds.
Results When applied together, the different connectivity rules allow the identification of priority areas that contain whole lakes or wetlands, their closest neighbours whenever possible, and the upstream/downstream reaches of rivers that flow into or from them. This would facilitate longitudinal and lateral movements of biota while minimizing the influence of disturbances potentially received from upstream or downstream reaches.
Main conclusions This new approach to defining and applying different connectivity rules can help improve the adequacy of freshwater-protected areas by enhancing movements of biodiversity within priority areas. The integration of multiple connectivity needs can also serve as a bridge to integrate freshwater and terrestrial conservation planning.
... In addition, FPA contribute to protect terrestrial species depending on riverine ecosystems (e.g., refuges in degraded landscapes or at times of drought, corridors for migration and dispersal; van Rees et al. 2020). In fact, as emphasized by Hermoso et al. (2012), FPA offer interesting opportunities for terrestrial conservation and vice versa. Therefore, targeting both realms simultaneously is recommended, generating higher benefits than those achieved by individual terrestrial and fluvial PA (Alvarez-Romero et al. 2011;Hermoso et al. 2012). ...
... In fact, as emphasized by Hermoso et al. (2012), FPA offer interesting opportunities for terrestrial conservation and vice versa. Therefore, targeting both realms simultaneously is recommended, generating higher benefits than those achieved by individual terrestrial and fluvial PA (Alvarez-Romero et al. 2011;Hermoso et al. 2012). (Petersen et al. 2022) Not enough relevance has been given to flows (Paxton et al. 2016) Declaration of Nature Reserves depends on the landowner's willingness and on the balance between conservation and economic needs (Kotzé 2012) Requires more investment on research (Nel et al. 2011b) ...
... The former ranks sites, independently from each other, in order of priority according to defined criteria (e.g., species richness, rarity or vulnerability) (Boon 2000; Abellán et al. 2005). On the other hand, methods based on complementarity, such as systematic conservation planning (SCP), are more recent and have received growing interest (e.g., Margules and Pressey 2000;Margules and Sarkar 2007;Hermoso et al. 2012) by providing, in a context of limited options and resources, a quantitative method for conservation prioritization using observed or modelled surrogate distributions (Pressey et al. 1993). SCP can be defined as "a structured stepwise approach to mapping conservation area networks, with feedback, revision and reiteration, where needed, at any stage" (Margules and Sarkar 2007). ...
Fluvial ecosystems are essential for life on Earth. Despite this recognition and the growing implementation of restoration programs, measures aimed at halting riverine biodiversity’s decline have had limited success, so far. The implementation of protected areas has been the cornerstone of terrestrial and marine conservation. However, this strategy has only been seldomly applied to the protection of fluvial ecosystems and there is still no clear evidence of its effectiveness. We reviewed existing literature in scientific journals and reports from conservation agencies and analysed existing protection policies dedicated to rivers as well as several case studies throughout the world. Our main aim is to understand the potential advantages and drawbacks of dedicated fluvial protected areas, comparing to terrestrial protected areas and even to the total absence of protection. We also delved in the process of implementing fluvial protected areas, namely in what concerns relevant spatial scales, conservation priorities, stakeholders’ involvement and mitigation measures to potential threats. In total 173 references were retained after a comprehensive search on Google Scholar, SpringerLink, Scopus and ResearchGate. These studies revealed that, despite contradictory results, terrestrial protected areas provide some degree of protection to riverine ecosystems contained within their borders, namely through increased abundances and species richness of some specific groups. Comparatively, however, dedicated fluvial protected areas, designed to accommodate the uniqueness of these systems, hold a much higher potential. Yet, data regarding its effectiveness is still scarce, mainly due to the lack of general guidelines and resources to evaluate performance following establishment, which prevents stronger conclusions.
... Therefore, accounting for spatial connectivity patterns at a catchment level is a complex, yet indispensable feature for designing effective management strategies for freshwater ecosystems (Adams et al., 2015). Still, freshwater connectivity issues have largely been overlooked in traditional conservation planning (Hermoso et al., 2012(Hermoso et al., , 2015. However, recent scientific interest is now on the rise (Hermoso et al., 2015Szabolcs et al., 2022), recognizing the need to adapt commonly used conservation principles designed for the terrestrial realm to the particular characteristics of freshwater environments (Hermoso et al., 2012(Hermoso et al., , 2015. ...
... Still, freshwater connectivity issues have largely been overlooked in traditional conservation planning (Hermoso et al., 2012(Hermoso et al., , 2015. However, recent scientific interest is now on the rise (Hermoso et al., 2015Szabolcs et al., 2022), recognizing the need to adapt commonly used conservation principles designed for the terrestrial realm to the particular characteristics of freshwater environments (Hermoso et al., 2012(Hermoso et al., , 2015. ...
... Hydrological connectivity among catchments is critical for freshwater ecosystems (Adams et al., 2015;Hermoso et al., 2012Hermoso et al., , 2015. European rivers are known to be highly fragmented by dams and other infrastructures, which can have detrimental effects on the connectivity of freshwater ecosystems and compromise crucial ecological processes (Alexandre and Almeida, 2010). ...
... Such disturbances lead to a mosaic of sub-habitats (e.g., oxbow lakes, isolated depressions, abandoned channels) that occur across most floodplains (Bellmore et al., 2015), thus determining connectivity across reaches, and between rivers and adjacent floodplains (Batzer et al., 2016;Penha et al., 2017;Dube et al., 2019;Reis et al., 2019). In these floodplains, multiple gradients (lateral and longitudinal) of hydrological connectivity, largely control the structure and diversity of the aquatic assemblages therein (Hermoso et al., 2012;Batzer et al., 2016). ...
... The first conceptual framework of rivers and their ecology focused on The River Continuum Concept (longitudinal connectivity; Vannote et al., 1980;Reese & Batzer, 2007;Guan et al., 2017). Longitudinal connectivity allows both long-and short-distance migration of biota through a river network (Hermoso et al., 2012). Therefore, from the headwaters to the downstreams, aquatic assemblages in river channels varied predictably (Batzer et al., 2016). ...
... These lateral floodplain waterbodies are inhabited by different representative species which contribute to the whole aquatic biodiversity of these ecosystems (Maire et al., 2015;Manfrin et al., 2020). By directly promoting the dispersal and indirectly altering the local habitat characteristics (e.g., water velocity, nutrient transport), both longitudinal and lateral hydrological connectivity between wetlands and river channels affect assemblage characteristics (Hermoso et al., 2012). Thus, examining the effects of longitudinal and lateral connectivity on aquatic assemblages of river floodplain wetlands is attracting attention (Manfrin et al., 2020). ...
Hydrological connectivity is crucial for supporting aquatic biodiversity and serving ecosystem function in river floodplain wetlands. Although the effects of longitudinal connectivity in the composition of snail (Mollusca: Gastropoda) assemblages is well understood, the effects of lateral connectivity are less evaluated. Here, we evaluated the effects of lateral and longitudinal connectivity on multiple facets of alpha and beta diversity (i.e., taxonomic, functional, and phylogenetic) of freshwater snails in 38 floodplain wetlands in the Da Xing'an Mountains of Northeast China. A total of 9,784 snails subjected to 5 orders, 14 families, 24 genera, and 42 species were collected. Overall, the snail alpha diversity was higher in the nearly isolated wetlands and downstream areas. Multivariate analyses revealed that the taxonomic, functional, and phylogenetic structures of snail assemblages in floodplain wetlands differed significantly across the lateral and longitudinal gradients. Waterscape and climate variables appeared to equivalently explain a large proportion of variations in the taxonomic, functional, and phylogenetic structures of snail assemblages. Lateral connectivity and river order were paramount variables that explain the greatest variation in taxonomic, functional, and phylogenetic structures of the snail assemblages. Our study suggests that hydrological connectivity is a key factor controlling the multiple facets of snail diversity in floodplains. Attention should be paid to the effects of changing climate and waterscape on the multi-faceted diversity of snail assemblages. Due to the extant patterns in assemblage structures, floodplain restoration and management should consider the full spectrum of longitudinal and laterally connectedness to maximize aquatic biodiversity.
... For decades, conservation scholars have advocated for engaging in conservation actions that transcend scales (Paloniemi et al. 2012) and that are conducted in a coordinated and integrated fashion (Soulé 1985;Salafsky et al. 2002;Knight et al. 2006). This is particularly salient for freshwater ecosystems given their inherent connection to the surrounding landscape (Hynes 1975;Hermoso et al. 2012;Lane et al. 2023) and that everything flows downstream (Vannote et al. 1980;Dodds and Oakes 2008). Yet, the norm for freshwater conservation efforts is to focus on a specific population or species, or specific places or spaces, rather than considering the scale at which freshwater systems function (Gomi et al. 2002;Vaughn 2010), the scale at which threats operate (Collen et al. 2014;Albert et al. 2021), and the scale at which conservation interventions need to be applied (Albert et al. 2021). ...
... Yet, the norm for freshwater conservation efforts is to focus on a specific population or species, or specific places or spaces, rather than considering the scale at which freshwater systems function (Gomi et al. 2002;Vaughn 2010), the scale at which threats operate (Collen et al. 2014;Albert et al. 2021), and the scale at which conservation interventions need to be applied (Albert et al. 2021). Therefore, key to freshwater conservation is embracing measures that consider all relevant scales (Hermoso et al. 2012), with a particular eye to integrating different processes and doing so in a coordinated manner (Cid et al. 2022). ...
Freshwater biodiversity is under great threat across the globe as evidenced by more severe declines relative to other types of ecosystems. One of the main stressors responsible for these concerning trends is habitat fragmentation, degradation, and loss stemming from anthropogenic activities including energy production, urbanization, agriculture, and resource extraction. Habitat protection and restoration both play an integral role in efforts to save freshwater biodiversity and associated ecosystem services from further decline. In this paper, we summarize the sources of threats associated with habitat fragmentation, degradation, and loss, and then outline response options to protect and restore freshwater habitats. Specific response options are to: legislate the protection of healthy and productive freshwater ecosystems; prioritize habitats for protection and restoration; enact durable protections; conserve habitat in a coordinated and integrated manner; engage in evidence-based restoration using an adaptive management approach; ensure that potential freshwater habitat alterations are mitigated or off-set; and future-proof protection and restoration actions. Such work should be done through a lens that engages and involves local community members. We identify three broad categories of obstacles that arise during the implementation of the response options outlined: a) scientific (e.g., inaccessible data or uncertainties), b) institutional and management (e.g., capacity issues or differing goals across agencies), and c) social and political (e.g., prioritizing economic development over conservation initiatives). The protection and restoration of habitats is key to bending the curve for freshwater biodiversity, with a comprehensive, connected, and coordinated effort of response options needed to protect intact habitats and restore fragmented, degraded, and lost habitats and the biodiversity and ecosystem services that they support.
... Conservation planning in freshwater ecosystems has lagged behind terrestrial and marine realms due to the complexity of river connections, the lack of distribution data, and their high spatial and temporal variability (Roux et al., 2008;Collier, 2011;Darwall et al., 2011). Previous studies have included freshwater particularities in conservation planning, i.e., accounting for longitudinal and lateral connectivity along stream networks, the importance of river flow, or using sub-catchments or river stretches as planning units instead of grid cells (Hermoso et al., 2011;Hermoso et al., 2012;Gomes-dos-Santos et al., 2019). However, systematic conservation planning exercises often overlook biotic interactions like predation, competition, parasitism, diseases, or mutualisms that might affect species persistence (but see Decker et al., 2017;Rayfield et al., 2009). ...
... Given that the objective of this study was to evaluate the influence of different conservation planning scenarios, we used a constant cost across all sub-catchments to rule out its potential influence from our solutions and make scenarios more comparable (e.g. Hermoso et al., 2012). We used a high SPF (SPF = 10) for all species to ensure that all of them achieve their targets. ...
Information about biotic interactions (e.g. competition, predation, parasitism, diseases, mutualism, allelopathy) is fundamental to better understand species distribution and abundance, ecosystem functioning, and ultimately guide conservation efforts. However, conservation planning often overlooks these important interactions. Here, we aim to demonstrate a new framework to include biotic interactions into Marxan. For that, we use freshwater mussels and fish interaction (as mussels rely on fishes to complete their life cycle) in the Douro River basin (Iberian Peninsula) as a case study. While doing that, we also test the importance of including biotic interactions into conservation planning exercises, by running spatial prioritisation analysis considering either: 1) only the target species (freshwater mussels); 2) freshwater mussels and their obligatory hosts (freshwater fishes); 3) freshwater mussels, fishes and their interactions. With this framework we found that biotic interactions tend to be underrepresented when the data on both freshwater mussels and fishes is not simultaneously included in the spatial prioritisation. Overall, the priority areas selected across all scenarios are mostly located in the western part of the Douro River basin, where most freshwater mussels and fishes still occur. Given the low overlap of priority areas identified here and the current Natura 2000 network, our approach may be useful for establishing (or enlarging) protected areas, especially in light of the EU Biodiversity Strategy for 2030. Also, this work may provide guidance for future habitat restoration and management of main threats to freshwater biodiversity.
... Similar to many studies that have taken a broad approach to understand how research evolves over time, we found a clear inclination towards publications from westernized nations, with almost two thirds of the research driven by three countries. While the USA and United Kingdom are consistently recorded as leading nations when it comes to peer-reviewed published research (e.g., Hill et al., 2021), Australia surprisingly made up a large portion (16.8%) of the locations where research is conducted (e.g., Hermoso et al., 2012). This may be because some of the most cited and published authors are or have been affiliated with Australian research institutions (e.g., Possingham, H. P.; Pressey, R. L.; Klein, C. J.). ...
Introduction
Biodiversity underpins resilient ecosystems that sustain life. Despite international conservation efforts, biodiversity is still declining due to ongoing anthropogenic threats. Protected areas have been widely adopted as a strategy for conserving biodiversity. The use of spatial conservation planning, which prioritizes areas for protection based on geo-referenced biodiversity and ecological information as well as cost of action and their feasibility, has gained popularity in the conservation discipline in the last few decades. However, there remain gaps between plans and implementation, and negative social impacts on local communities can occur, such as tension and conflict between differing priorities, perspectives, and views.
Methods
To better understand the state of the spatial conservation field and support translating research into practice, a mixed-method approach of bibliometric (n=4133 documents) and content analysis (n=2456 documents) was used to analyze and identify key research priorities, collaborative networks, and geographic and thematic patterns.
Results
We identified that research conducted by westernized nations dominated the field, with the United States, the United Kingdom, and Australia being responsible for almost two-thirds of the research globally, with research interest exponentially growing since 2010. Additionally, while there has been some refinement over time of algorithms and models, Zonation and Marxan methods developed in the 2000s remain the predominant choices of software, with a majority focus on marine ecosystems, birds, and mammals. We found a major gap in the use of social dimensions in spatial conservation case studies (only n=146; 6%).
Discussion
This gap highlights a lack of collaboration in conservation science between researchers and local communities who are affected by management decisions. We recommend including spatially explicit social dimensions from the onset of projects through participatory approaches, along with the acknowledgement by researchers of the importance of including diverse views in conservation planning to enhance implementation and outcomes that are relevant in local contexts. We suggest an increased reflection on types of data used for conservation but also on researchers’ personal values, biases, and positionality to encourage more ethical, applicable, and collaborative conservation science.
... Society's increasing demand for water has led to a transformation of the river network into a succession of reservoirs or canals, sectioned off by various hydro-engineering works, generating numerous debates about the impact of these structural interventions on aquatic systems [1][2][3][4], and not least on communities. In addition to this hydro-geomorphological alteration, there is also a chemical and thermal alteration, either directly through wastewater effluent or insufficiently treated water, or through the fact that the physico-chemical characteristics of the water volumes in the riverbed are strongly influenced by climatic factors [5][6][7][8]. ...
Anthropogenic pressure on water resources is affecting aquatic systems, requiring ecological analysis and restoration. This study proposes a new approach to assessing public perceptions of these activities. The methodology used is based on a structured questionnaire that looks at the general perception of the research topic, the economic readiness for community involvement and the identification of institutional mechanisms to implement river restoration measures. We used random sampling, guaranteeing results with a margin of error of 4.33%. The results show that the public and practitioners have different perspectives, and this can influence river restoration solutions, as they will contribute to a change in the way that longitudinally connected river restoration solutions are designed and implemented.
... Identification of the priority river stretches is one of the most important tenets of the systematic conservation planning, which is followed by monitoring of spatial and temporal biodiversity changes, implementing stringent measures to reduce pollution, enforcing sustainable fisheries management practices, implementing measures to safeguard and restore riverine habitats, engaging local Das et al. communities and stakeholders participation, awareness programs to enhance understanding about the importance of biodiversity conservation, consideration of socio-economic aspects and potential conflicts between conservation goals and human activities and ensuring alignment with existing conservation laws and policies, along with implementation of new protective measures (Hermoso et al., 2012;Bond et al., 2014;Linke et al., 2019). Addressing these points makes systematic conservation planning a more effective and inclusive process, contributing significantly to the long-term protection of biodiversity and ecosystems. ...
... Improving the information on the distribution of biodiversity is especially urgent in the case of freshwater ecosystems as they are particularly affected by global change, even more than their terrestrial or marine counterparts (Hermoso et al., 2012;Reid et al., 2019;WWF, 2020). Compared with terrestrial invertebrates, freshwater species have smaller geographic ranges, lower dispersal abilities and higher endemism levels (Dudgeon et al., 2006). ...
Aim
Understanding biodiversity patterns is crucial for prioritizing future conservation efforts and reducing the current rates of biodiversity loss. However, a large proportion of species remain undescribed (i.e. unknown biodiversity), hindering our ability to conduct this task. This phenomenon, known as the ‘Linnean shortfall’, is especially relevant in highly diverse, yet endangered, taxonomic groups, such as insects. Here we explore the distributions of recently described freshwater insect species in Europe to (1) infer the potential location of unknown biodiversity hotspots and (2) determine the variables that can anticipate the distribution of unknown biodiversity.
Location
The European continent, including western Russia, Cyprus and Turkey.
Methods
Georeferenced information of all sites where new aquatic insect species were described across Europe from 2000 to 2020 was compiled. In order to understand the observed spatial patterns in richness of recently described species, spatial units were defined (level 6 of HydroBASINS) and associated with a combination of a set of socioeconomic, environmental and sampling effort descriptors. A zero‐inflated Poisson regression approach was used to model the richness of newly described species within each spatial unit.
Results
Nine hundred and sixty‐six recently described species were found: 398 Diptera, 362 Trichoptera, 105 Coleoptera, 66 Plecoptera, 28 Ephemeroptera, 3 Neuroptera, 2 Lepidoptera and 2 Odonata. The Mediterranean Basin was the region with the highest number of recently described species (74%). The richness of recently described species per spatial unit across Europe was highest at mid‐elevation areas (between 400 and 1000 m), latitudes between 40 and 50° and in areas with yearly average precipitation levels of 500–1000 mm, a medium intensity of sampling effort and low population density. The percentage of protected areas in each study unit was not significantly related to the richness of recently described species. In fact, 70% of the species were found outside protected areas.
Main conclusions
The results highlight the urgent need to concentrate conservation efforts in freshwater ecosystems located at mid‐altitude areas and out of protected areas across the Mediterranean Basin. The highest number of newly described species in those areas indicates that further monitoring efforts are required to ensure the aquatic biodiversity is adequately known and managed within a context of growing human impacts in freshwater ecosystems.
... Another factor impairing the efficacy of restoration measures is the disruption of longitudinal connectivity [15,25,84]. The lack of stream continuity for fish and hololimnic invertebrates, for example as a result of the construction of migration barriers, has a direct impact on the migration of aquatic organisms, the species composition of the biocenosis, and the recolonization of restored river stretches [15,[109][110][111]. For example, Ramírez et al. [112] did not detect native fish species in streams of Turabo (Puerto Rico, USA) due to a lack of continuity and migration routes. ...
Background
For more than 20 years, restoration measures have been conducted on watercourses in Germany to increase habitat diversity and thus promote biodiversity. However, their ecological efficacy often proved to be limited. While some studies report an increase in species diversity, others show little evidence of improvement even many years after the implementation of restoration measures. In general, ecological efficacy of hydromorphological restoration measures is highest for terrestrial and semiaquatic groups of organisms such as floodplain vegetation and ground beetles. According to the literature, macrophytes responded most strongly to in-stream restoration measures, while fish stocks showed little improvement and macroinvertebrates showed little or no effect in terms of species richness and diversity. These findings raise the question of reasons for the low ecological efficacy of hydromorphological restoration measures, especially for macroinvertebrate communities. The following literature review and a case study for the river Horloff will provide possible indications for failing success of intensive restoration measures.
Results
One reason for the inadequate ecological status of many restored river stretches is the inappropriate scaling of restoration measures. Often, small-scale restoration measures are planned, although the respective water bodies exhibit stressors at the catchment scale that impair the ecological efficacy of restoration measures. In particular, chemical contamination of running waters is often insufficiently addressed in the planning and implementation of restoration measures and hampers efficacy of hydromorphological restoration measures. For a holistic water resource management, the planning and implementation of measures should therefore be more closely coordinated and harmonized between federal states and neighboring countries. For this purpose, the establishment of so-called river basin communities is suitable, as they already exist today on the rivers Rhine, Danube, Meuse, Weser, Elbe, Ems, Eider, Schlei/Trave, Warnow/Peene.
Conclusion
The literature review indicated that for a successful recolonization of restored river stretches by macroinvertebrates and the enhancement of the ecological status, large-scale stressors, i.e., stressors acting at the catchment scale, should be eliminated initially by restoration measures focusing on the chemical contamination and the surrounding land use. Structural restoration measures acting on the reach or local scale should ideally be implemented contemporarily to the removal of large-scale stressors like chemical contamination.
... We accounted for upstream relationships such that solutions selecting downstream reaches in isolation would have a higher boundary length, leading to a larger, less optimal score (Eq. 1); this approach has proven useful for designing the longitudinally connected reserve networks essential for conserving freshwater systems (Beger et al. 2010b;Hermoso et al. 2012). ...
Context
Cross-scale analyses are central to understanding patterns and processes in hierarchically structured ecological systems. Systematic conservation planning has progressed in recent years, but the utility of cross-scale planning efforts has received little valuation.
Objectives
Our goal was to develop and evaluate a scale-linked framework to prioritize spatial units for conservation. We sought to compare the spatial configuration and cost-efficiency of a conservation network designed using data collected and analyzed at two spatial scales (e.g., both regional and local) with that produced using a more traditional single-scale approach (e.g., local).
Methods
We sampled macroinvertebrate communities from 48 representative streams within the
Congaree Biosphere Region in 2019. We developed random forest models to predict distributions of community-level metrics at regional (subwatershed) and local (local catchment) spatial scales. Finally, we prioritized planning units according to their conservation value, relative to three biotic metrics, under two
different scenarios: a traditional ‘single-scale’ and novel ‘scale-linked’ approach.
Results
Spatial differences between our single-scale and scale-linked scenarios were apparent. On average, solutions produced by our scale-linked scenario were 4.96% less costly and required 4.71% fewer planning units than our single-scale scenario. Scale-linked solutions were penalized an average of 15.90% less than single-scale solutions, reflecting a greater capacity to adequately represent the biotic metrics of
interest.
Conclusion
Our comparisons suggest that scale-linked approaches can decrease cross-scale disparities and better reflect hierarchical processes without sacrificing planning efficiency. Thus, scale-linked conservation planning may help ease implementation efforts while enhancing the long-term resilience and sustainability of landscapes surrounding protected areas.
... The next step would be a systematic selection and prioritization of the most important refuges to ensure the resilience of the amphibian populations in the Sabor river basin (Margules & Pressey, 2000). Such selection should take into account the connectivity FCUP Modelling biodiversity patterns and processes to support conservation in stream networks 243 Ch7 among populations, and the structure and seasonality of the stream network (Hermoso et al., 2012(Hermoso et al., , 2013. reported the expansion speed for the invasive crayfish in the Sabor basin. ...
Biodiversity is not evenly distributed across our planet. Freshwater ecosystems hold a disproportionate amount of biodiversity when compared with other biomes, though it only covers a small portion of our planet surface. Because water is essential for human activities, population growth and economic development put an enormous pressure on freshwater ecosystems. Besides the direct anthropogenic pressures, such as over exploitation, damming, habitat modification and pollution, the freshwater species usually present restricted distributions, to a watershed or a region, and face the threat of hundreds of invasive species that have been introduced to freshwater ecosystems. Due to all these factors, freshwater biodiversity is among the most threatened of our planet.
Stream networks deserve special attention because they are particularly threatened and rich in biodiversity. Streams networks are linear bodies of water with a dendritic, or tree shape, organization, flowing from the headwaters to a single outlet. The distribution of organisms in stream networks are not random, resulting from several processes that work at different scales, like climate, hydrology and biotic interactions. The diversity and abundance of fish and many other organisms are usually associated with an increase in stream order, but there are also dispersal processes that should be taken into account. The distribution of some species, like invasive species, is often more a reflection of spatial processes, such as multiple introductions and posterior expansion, than environmental filters that limit the distribution. Headwaters can function as refuges from adverse biotic interactions for species that support water intermittency. Stream communities, like fish, usually persist in time in a state of dynamic equilibrium, varying between alternate states with no discernible direction of change. Deviations from this equilibrium may reflect disturbances to the community from natural states, like droughts or floods, or from anthropogenic sources. For proper conservation and management of stream networks, it is essential to understand the drivers of the spatial patterns and dynamics of stream biodiversity.
Species distribution models (SDM’s) are the set of tools used to derive spatially-explicit predictions of environmental suitability, by relating species occurrences to relevant environmental data. Due to their nature and the nature of the stream network habitats, the development of SDM’s for organisms that are associated with streams is challenging. Aquatic organisms are rarely available for direct observation, and even with the help of standard techniques, like electrofishing, it is fair to assume that we will fail to detect some of the species present at any given location. This issue, known as imperfect detectability, is a common source of bias in SDM’s, and tends to be ignored by freshwater researchers. Accounting for spatial autocorrelation (SAC) improves SDM performance, but the dendritic structure of stream networks, together with strong environmental gradients, create spatial dependences with complex structures that are not completely described by Euclidean distances. Biotic interactions, such as competition or predation, are also a potential source of mismatch between the actual and the predicted distribution of species, particularly if the interactions are between invasive species and native species. Long term monitoring of communities is essential to understand the impact of anthropogenic pressures in stream ecosystems, but usually rely on data collected on any given number of discrete locations. A spatial continuous view of the temporal dynamics would be essential to study such pressures, and of value to plan conservation and management actions.
The main aim of this thesis is to develop new tools and frameworks to help ecologists and conservationists to obtain a more realistic depiction of the distribution of species, and the temporal dynamics of communities at the riverscape scale. I mainly focused on solutions to the issues related to dealing with imperfect detectability, accounting for SAC in stream networks, accounting for biotic interactions, and extrapolating the community temporal dynamics to a continuous spatial prediction. To address these issues, I have collected data on the distribution of fish, crayfish, and amphibians on a specific study system, the Sabor River, a Mediterranean watershed in the Northeast of Portugal.
To describe the distribution of fish species with data collected in a comprehensive electrofishing survey, while accounting for imperfect detectability, we extended the time-to-detection occupancy-detection model to include interval-censored observations, because it is difficult to ascertain the exact time-to-detection of a species when sampling fish with electrofishing techniques. Using a Bayesian hierarchical framework, we modelled the probability of water presence in stream segments, and the probability of species occupancy conditional on water presence, in relation to environmental and spatial variables. We also modelled time-to-first detection conditional on occupancy in relation to local factors, using a modified interval-censored exponential survival models. To account for SAC, we included a spatial autocovariate term in the estimation of the probability of water presence and the probability of species occupancy. Species occupancies were consistently affected by stream order, elevation and annual precipitation, while species detection rate was primarily influenced by depth and, to a lesser extent, stream width.
The assumption of equilibrium between organisms and their environment is a standard working postulate in SDM’s that is seldom met, particularly for species that are expanding their range like invasive species. Furthermore, for species invading river systems, the dendritic structure of the stream network will constrain the patterns of the expansion. In this thesis, I addressed these issues by describing the distribution of two invasive crayfish in the Sabor river stream network, using a class of geostatistical models developed to deal with SAC in stream networks, known as spatial stream network models (SSNM). Accounting for SAC greatly improved model performance, evidencing that the distribution of these invasive crayfish was more of a product of spatial process than environmental filtering.
Biotic interactions are important drivers of species distributions. When native species are displaced from part of their distributional range, they may persist in ecological refuges. These refuges may be patches of habitat that are unsuitable for invasive species or areas where invasive species have not reached due to distance, physical barriers or time lags in the expansion. Identifying the distribution and the environmental drivers of these refuges is of conservation concern. We modelled the distribution of amphibian ecological refuges in the Sabor river catchment, by including as predictor variables the probability of presence of the two invasive crayfish, among other environmental and spatial predictors. We found that the refuges of amphibians are located mainly in the headwaters, and that, under plausible expansion scenarios of the crayfish species, these refuges are likely to contract in the future.
Management of stream networks is usually planned at the river basin scale, and as such, it is important to develop frameworks that allow the extrapolation of the community dynamics observed at discrete segments of rivers to a continuous spatial view of the entire river basin. We collected stream fish data on 30 locations on the Sabor river basin, between 2012 and 2019, and used a novel framework to describe and compare the trajectories of the fish communities using their geometric properties in a given dissimilarity space. We computed the mean velocity and the overall directionality of change of the fish community, and used the SSNM framework to relate these metrics to environmental drivers and extrapolate the community dynamics to the entire watershed. We found no evidence of directionality in the change of the Sabor fish communities, supporting the hypothesis that these communities exist in a loose equilibrium state. However, the rate of change was higher in streams draining into the hydroelectric reservoir located near the mouth of the Sabor River. These streams are likely under increased stress from the reservoir, due to alterations of the flow regime and/or expansion of alien species from the reservoir.
Overall this thesis advances our understanding of the drivers that govern the distribution of species in stream networks, providing key information for the conservation of these ecosystems. The new set of tools presented here can aid ecologists and conservationists to obtain a more realistic depiction of species distribution and their temporal dynamics at the riverscape scale.
... Systematic conservation planning has five fundamental principles, which are representation, complementarity, adequacy, efficiency, and spatial compactness [15,17]. It is widely applied in Australia, the United States, and South Africa [18][19][20]. For example, in Ecuador, systematic conservation planning using Marxan software was applied in combination with species distribution modelling using Maxent with the aim of increasing the representation of terrestrial species diversity in the protected areas network [21,22]. ...
The present study aims to use systematic conservation planning to analyse and review the national protected areas (PAs) network in Jordan. The analysis included the application of three modules: the environmental risk surface (ERS), the relative biodiversity index (RBI), and the application of Marxan. The methodology was based on using Marxan to achieve solutions for three scenarios for the PAs network. Marxan was applied to the input data, which included vegetation types, distribution of threatened mammals and plants, locations of currently established PAs and other types of designations. The first two scenarios aimed to conserve 4% and 17%, respectively, of each vegetation type, and 10% and 20%, respectively, of the extent of occurrence of threatened mammals and plants. The third scenario aimed to conserve 17% of each vegetation type and 10% of the extent of occurrence of threatened plants and mammals, except for forest and the Hammada vegetation which had the target of 30% and 4%, respectively. The results of the three scenarios indicated that the boundaries of existing reserves should be extended to achieve the conservation targets. Some currently proposed (PAs), such as the Aqaba Mountains, did not appear in any of the solutions for the three scenarios indicating that the inclusion of these sites in the proposed (PAs) network should be reconsidered. All three scenarios highlighted the importance of having conservation areas between the western and eastern parts of the country. Systematic conservation planning is a structured, replicable, transparent, and defensible method for designing PA networks. It allows for finding efficient solutions building on what is currently conserved and minimizing the fragmentation and cost of the proposed solution for conservation areas.
... While the implementation of effective conservation actions is always challenging (Beatty et al., 2014;Collier, 2011;Esselman & Allan, 2011;Hermoso et al., 2018), the design of protected river networks can now benefit from insights and tools provided by a long experience in conservation planning of terrestrial and marine systems (Margules & Pressey, 2000;Watson et al., 2014). Likewise, more recent advances and developments of conservation prioritization methods have been dedicated to running waters (Alexander et al., 2018;Hermoso et al., 2012Hermoso et al., , 2016Moilanen et al., 2008). ...
Aim
Estimate the current and future distribution of brown trout and identify priority areas for conservation of the species.
Location
Rhône River basin and Mediterranean streams.
Methods
We first developed a spatially explicit species distribution model to estimate the current and future distribution of brown trout for three time horizons (2030, 2055 and 2080) and two climate change scenarios (RCP 4.5 and RCP 8.5). We then performed a prioritization analysis to identify priority areas for brown trout conservation, accounting for: (a) spatial dependencies along the riverine system, (b) several sources of uncertainty arising from climate-related forecasts and (c) different protected area scenarios by comparing hypothetical, optimal protected networks to an actual protected network designed by regional fish experts.
Results
Future projections of brown trout densities exhibited a general trend towards a gradual range contraction, with a significant risk of extirpation across mountainous regions of low to mid-elevation. Overall, the projected current and future distributions were well-covered by the existing protected network. In addition, up to 70% of the river reaches included in this expert-based protection network were also priorities in the optimal priority set (e.g. the best set of areas to maximize biodiversity protection). Finally, a large proportion of these reaches were invariably identified regardless of climate change scenarios and uncertainties or spatial dependencies.
Main conclusions
Our analytical approach highlighted priority areas for brown trout conservation which were robust to a set of climate and connectivity assumptions. This core priority network could be further refined by taking into account key fine-scale processes like thermal refugia. Therefore, we advocate for combining computational and expert-based approaches in conservation planning of riverine ecosystems to achieve a relevant consensus between regional-scale management and fine-grain ecological knowledge.
... Freshwater aquatic ecosystems are linked to each other and their accompanying terrestrial systems, but our analysis did not account for important flows of energy, populations, or water from one HUC8 to another [12,98,99]. The forested area dataset did not include stand age or reforestation history, which are important for many fish species [100,101]. ...
Freshwaters are important, interconnected, and imperiled. Aquatic ecosystems, including freshwater fishes, are closely tied to the terrestrial ecosystems they are embedded within, yet available spatially explicit datasets have been underutilized to determine associations between freshwater fishes and forested areas. Here, we determined the spatial co-occurrence between freshwater fish distributions and forests within 2129 watersheds of the conterminous United States. We identified 21% of freshwater fishes as associated with forested areas, and 2% as strictly present only in highly forested areas (75–100% forested). The northern coasts and southeast regions, both heavily forested, showed the largest numbers of forest-associated fishes in highly forested areas and fish species richness. Fish associated with low-forested areas occurred in the southwest and central plains. Imperiled fishes were relatively evenly distributed among percent forest categories, which was distinctly different from patterns for all fishes. The identification of forest-associated fishes provides insights regarding species-specific landscape contexts. Determining these large-scale patterns of freshwater biodiversity is necessary for conservation planning at regional levels, especially in highly impacted freshwater ecosystems.
... Freshwater conservation planning has emerged as a rapidly growing discipline in recent years due to the progress of Systematic Conservation Planning (SCP) in the freshwater realm Linke et al., 2011Linke et al., , 2012Linke et al., , 2019Hermoso et al., 2011Hermoso et al., , 2012Langhans et al., 2014;Flitcroft et al., 2019). SCP can prioritize irreplaceable biodiversity pattern through a complementarity-based planning framework, and maximize its effectiveness by using limited resources to achieve conservation goals (Margules and Pressey, 2000;Cowling and Pressey, 2003). ...
Freshwater wetlands play an important role in preserving global biodiversity and substantial ecosystem services, but they are exposed to higher pressures and threats and have received less attention in conservation planning in comparison to terrestrial ecosystems. Although a number of freshwater protected areas have been established in China, considerable freshwater conservation gaps still exist where ecologically valuable freshwater wetlands are vulnerable to anthropogenic threats, our study therefore explored systematic conservation planning specifically suited to freshwater ecosystems for the large river basins in China. A scheme of Climatic-geomorphological Classification of Freshwater Ecosystems (CGCFEs) was developed and employed as broad-scale surrogates based on their unique ecohydrological processes and biodiversity assemblages. A freshwater conservation assessment was conducted for each river basin using a complementarity-based planning framework (i.e., systematic conservation planning) and the prioritization software Marxan in consideration of the conservation targets of CGCFEs. Our research also demonstrated the need to introduce the concept of incidental gaps (IGs) in freshwater conservation planning, where the focal species and ecosystems have unintentionally been incorporated into a nature reserve with different conservation targets and thus created “conservation gaps” due to incidental and unfocused conservation efforts. The identified complete gaps (CGs) and IGs accounted for 10.56% and 8.66% of the total freshwater area respectively, implicating the need to enhance freshwater conservation efficacy by realigning existing conservation patterns to address these gaps. Our research provides a spatially explicit freshwater conservation strategy at the river basin and national scales and thus enables the central government and wetland resource managers to set ecologically meaningful spatial conservation priorities for freshwater ecosystems within those major large river basins. In addition, the methodology of using CGCFEs can be replicated for large-scale freshwater conservation planning elsewhere and promote freshwater conservation efficiency by capturing irreplaceable freshwater habitats.
... Third, KBAs boundaries should be planned at the subcatchment level to ensure long-term persistence of trigger species, given that spatial (longitudinal, vertical, lateral) and temporal connectivity play a major role in the dynamics of freshwater ecosystems (Hermoso et al., 2012). Focal areas identified for freshwater KBAs will likely become the boundaries of the validated KBAs, instead of the wider subcatchment, which, as demonstrated here, can lead to the omission of important trigger species. ...
Theidentification of key biodiversity areas (KBA) was initiated by the International Union for Conservation of Nature in 2004 to overcome taxonomic biases in the selection of important areas for conservation, including freshwater ecosystems. Since then, several KBAs have been identified mainly based on the presence of trigger species (i.e., species that trigger either the vulnerability and or the irreplaceability criterion and thus identify a site as a KBA). However, to our knowledge, many of these KBAs have not been validated. Therefore, classical surveys of the taxa used to identify freshwater KBAs (fishes, molluscs, odonates, and aquatic plants) were conducted in Douro (Iberian Peninsula) and Sebou (Morocco) River basins in the Mediterranean Biodiversity Hotspot. Environmental DNA analyses were undertaken in the Moroccan KBAs. There was a mismatch between the supposed and actual presence of trigger species. None of the trigger species were found in 43% and 50% of all KBAs surveyed in the Douro and Sebou basins, respectively. Shortcomings of freshwater KBA identification relate to flawed or lack of distribution data for trigger species. This situation results from a misleading initial identification of KBAs based on poor (or even inaccurate) ecological information or due to increased human disturbance between initial KBA identification and the present. To improve identification of future freshwater KBAs, we suggest selecting trigger species with a more conservative approach; use of local expert knowledge and digital data (to assess habitat quality, species distribution, and potential threats); consideration of the subcatchment when delineating KBAs boundaries; thoughtful consideration of terrestrial special areas for conservation limits; and periodic field validation.
... Management strategies that have focused only on one key aspect and have simplified riverscapes have inevitably failed. Multi-landscape planning that encompasses streams, rivers and adjacent riparian forests which go beyond conventional planning of a single landscape unit, have had overarching benefits (Naiman and Rogers, 1997;Hermosa et al., 2012;Adams et al., 2014). We implemented a novel field design to study riparian forest use across an entire catchment. ...
While the negative impacts of dam construction on downstream river stretches and riparian forests are well studied, the status of wildlife presence and persistence in upstream reservoir deltas is virtually unknown. We investigated the drivers of terrestrial mammal occupancy and persistence along riparian forests of Koyna reservoir in western India 55 years after its construction. We adopted a catchment-wide field design grounded in the river continuum concept and sampled different stream orders within the reservoir. Camera traps, nested in an occupancy modeling framework, were deployed across 72 riparian sites and replicated for four seasons across all stream types. We recorded a total of nineteen species of terrestrial mammals during the study period. Multi-season occupancy models revealed three key patterns of mammal persistence: (a) ungulates were more frequently photo-captured in riparian forests; gaur and wild pig had the highest proportions of the total sampled area (0.84 ± 0.12 SE; 0.77 ± 0.07 SE, respectively); (b) small-sized ungulates were more vulnerable to local extinction than large-bodied ungulates; extinction probability was highest for barking deer (0.59 ± 0.07) and lowest for sambar (0.15 ± 0.07); and (c) distance from stream played major roles in determining mammal detection. Riparian forests are fundamentally important to ecosystem functioning and biodiversity conservation, and using the data from this study, managers can plan to sustain high mammal persistence along riparian forests at Koyna reservoir or similar Indian reserves. Further, our robust sampling approach, grounded in the terrestrial-riverine continuum concept, can be applied globally to understand species assemblages, aiding in multi-landscape and wildlife management planning.
... Ephemeral wetlands are key habitats for unique fauna and flora (Williams 2006;Werner et al. 2007), but also act as ecological corridors connecting freshwater bodies (Rains et al. 2016). Connectivity is fundamental for the conservation of biodiversity in freshwater environments (Hermoso et al. 2012), hence the planning of new protected areas for Patagonia should consider this parameter and also the social context (i.e. avoid conflicts with local people; see García-Llorente et al. 2018). ...
Given the multiple stressors affecting freshwater ecosystems and the limited resources devoted to their management, effective conservation of freshwater biodiversity requires regional prioritization. Patagonian wetlands are essential for regional biodiversity and the economy, but they are still far from reaching global conservation targets and many of them could disappear due to climate change. Our study aimed at prioritizing wetlands based on aquatic and terrestrial biodiversity, their conservation status and vulnerability to climate change. First, we identified 43 priority wetlands containing all aquatic biodiversity collected in 82 Patagonian wetlands located over a 1500 km north–south gradient, by using the software Marxan. Then, we ranked within priority wetlands according to their conservation status (low priority if they were already protected; medium priority if not), importance for terrestrial biodiversity conservation (high priority) and vulnerability to climate change. Highly ranked priority wetlands in National Parks (low priority), contained diverse wetlands (57% aquatic taxon richness), including a large proportion of rare species (33%). High priority wetlands are oases of water in an arid and semiarid steppe, containing not only a large proportion of the aquatic biodiversity, but also acting as a refuge for terrestrial flora and fauna. Different management actions are proposed according to wetland priority level (e.g. fencing, creation of artificial ponds), and since 20% of medium priority and 36% of high priority wetlands are expected to disappear by 2050, their inclusion in conservation or restoration plans needs to be carefully evaluated.
... The event is marked in the sedimentary record by a pronounced negative carbon isotope excursion (CIE) between two positive ones, and is widely documented in records of organic-rich, black shale sediments (e.g. Hesselbo et al. 2007;Suan et al. 2008Suan et al. , 2015Jenkyns 2010;Hermoso et al. 2012). The associated mass extinction entailed the disappearance or reduction of many forms of ammonoids, ostracods, brachiopods, foraminifera, echinoderms and calcareous nannofossils (Dera et al. 2010;García Joral et al. 2011;Gómez and Goy 2011;Rita et al. 2016;Reolid et al. 2018Reolid et al. , 2019Slater et al. 2019;Soulimane et al. 2020). ...
Recent ichnological analysis conducted in two sections (Rodiles and Lastres) of the Asturian Basin revealed the presence of Halimedides Lorenz von Liburnau 1902, which occurs just above the black shales related to the end of the T-OAE. Halimedides is associated with the recovery of the tracemaker community after the reestablishment of favourable, oxic, conditions. The appearance of Halimedides after the T-OAE event, previously not registered, supports the close relationship of the tracemaker with oxygen conditions, as occurs in other anoxic events including the Cretaceous OAE-1a and OAE-2. Also a relation between morphometric and paleoenvironmental parameters is observed, occurring larger and densely chambered specimens in darker, weakly oxygenated facies, while smaller and sparsely chambered forms are registered in lighter, better oxygenated sediments.
... Second, we calculated the connectivity between connected watersheds based on the methodology in Hermoso et al. (2012). The exterior boundary, or boundary length modifier (which is the connectivity parameter used for terrestrial or marine conservation planning), is not an appropriate measure of freshwater connectivity because fish can only move upstream and downstream between planning units (Hermoso et al. 2011;Linke et al. 2012). ...
Freshwater ecosystems show more biodiversity loss than terrestrial or marine systems. We present a systematic conservation planning analysis in the Arctic Ocean drainage basin in Ontario, Canada, to identify key watersheds for the conservation of 30 native freshwater fish, including four focal species: lake sturgeon, lake whitefish, brook trout, and walleye. We created species distribution models for 30 native fish species and accounted for anthropogenic impacts. We used the “prioritizr” package in R to select watersheds that maximize species targets, minimize impacts, and meet area-based targets based on the Convention on Biological Diversity commitment to protect 17% of terrestrial and freshwater areas by 2020 and the proposed target to protect 30% by 2030. We found that, on average, 17.4% and 29.8% of predicted species distributions were represented for each of the 30 species in the 17% and 30% area-based solutions, respectively. The outcomes were more efficient when we prioritized for individual species, particularly brook trout, where 24% and 36% of its predicted distribution was represented in the 17% and 30% solutions, respectively. Future conservation planning should consider climate change, culturally significant species and areas, and the importance of First Nations as guardians and stewards of the land in northern Ontario.
... However, the Amazon basin still needs effective conservation actions to safeguard freshwater biodiversity, mostly in large rivers and their floodplains. These actions should include systematic conservation planning and appropriate methods based on freshwater ecological characteristics to design an effective series of freshwater PAs (Hermoso, Kennard, & Linke, 2012;Jézéquel, Tedesco, Darwall, et al., 2020;Linke, Turak, & Nel, 2011;. ...
• The Amazon basin has been subjected to extreme climatic events and according to climate change projections this hydrosystem could face changes in the natural dynamic of flood cycles that support the feeding and reproduction of many fish species, threatening aquatic biodiversity.
• Protected areas (PAs) are the main tools used to safeguard the biodiversity in the long term; however, they are fixed areas that could be subject to climate change, questioning their future efficiency in protecting biodiversity.
• The Amazon basin currently benefits from a relatively high level of protection as 52% of its catchment area is under the form of true PAs or indigenous lands. However, the capacity of these PAs to protect freshwater biodiversity remains unclear as they have generally been assessed with little regard to freshwater ecosystems and their hydrological connectivity. Here, the aim was to evaluate the effectiveness of PAs in representing the Amazon fish fauna under current and future climatic conditions.
• A macroecological approach was used to estimate the minimum size of the geographical range needed by each species to achieve long‐term persistence, by a combined function of range size and body size, two ecological traits known to influence species extinction risk.
• In future the Amazon basin could risk losing 2% of its freshwater fish fauna owing to unsuitable climatic conditions, with a further 34% adversely affected. The present Amazon network of PAs will cover the minimum required range for species persistence for more than 60% of the freshwater fish species analysed under the future climate scenario. However, more than 25% of the future susceptible species are currently concentrated in large tributaries and in the central‐lower Amazon floodplain where few PAs occur, highlighting the lack of appropriate conservation actions for these specific water bodies.
... Furthermore, this information can be combined with details of waterhole morphology and calibrated to account for inputs and losses, to provide the most accurate approach to modelling waterhole persistence. Modelling of waterhole persistence informs management of arid-zone, ephemeral river systems by identifying key waterholes and facilitating the conservation of aquatic habitat (Hermoso et al. 2012;Costelloe and Russell 2014) and ecosystems (Bond et al. 2015). ...
The episodic, seasonal hydrology of Lake Eyre Basin (LEB) rivers produce a series of waterholes which provide critical aquatic refugia and essential water supply during predominantly dry periods. This study used direct measures of water loss, regional meteorological data, and waterhole bathymetry to develop calibrated waterhole persistence models in a range of waterhole types throughout the Queensland portion of the LEB. Evaporation was a major driver of waterhole persistence, whereas the influence of other water balance parameters (e.g. groundwater discharge, seepage, vegetation utilisation) varied between waterholes and years. Estimates of waterhole persistence were extrapolated to the regional scale using a modelled time-series of waterhole level data and Landsat satellite imagery (1988–2019). Strong relationships were calculated between waterhole level and waterhole area (r² = 0.88) and waterhole level and number of waterholes (r² = 0.79) for all regional waterhole zones. Using these relationships and predicted evaporation rates under three possible future greenhouse gas scenarios, modelling showed that, by 2070, the number of persistent waterholes could reduce by up to 67% over 12 month period without flow. Similarly, reductions in waterhole area of up to 72% are possible under drier climate scenarios. These results potentially represent a significant risk to the aquatic ecosystems and other waterhole-dependent users for an already limited resource.
... Human alterations to riverscapes affect each of these dimensions and result in changes to natural structuring mechanisms for biotic assemblages (Cooper et al., 2017;Dudgeon et al., 2006;Perkin et al., 2015). Consequently, design of freshwater protected areas must integrate information across multiple riverscape dimensions to identify areas where anthropogenic alterations can be mitigated to benefit the greatest number of species (Hermoso et al., 2012). Freshwater stream fishes serve as biological indicators of multi-dimensional riverscape connectivity (e.g., Perkin et al., 2017;Schmutz & Jungwirth, 1999) and are commonly used to identify freshwater protected areas (Araújo & Williams, 2000;Williams et al., 2011). ...
Aim
To review the conservation status of Headwater catfish Ictalurus lupus (Girard,1859) in the United States, including quantifying environmental correlates with range contraction and hybridization and introgression with Channel catfish Ictalurus punctatus (Rafinesque, 1818) to inform conservation prioritization.
Location
Texas and New Mexico, USA.
Methods
We used random forest models to construct species distribution models (SDMs) based on historical (1980–1999) and contemporary (2000–2019) data and 13 classes of remotely sensed stream network data. We measured hybridization and introgression with the widely introduced Channel catfish using external morphology, mitochondrial DNA (mtDNA), and a nuclear gene (RAG2).
Results
Species distribution models illustrated temporal reduction in suitability for Headwater catfish among the species’ namesake headwater streams, including streams with steeper slopes, faster velocities, and higher elevations. Modelling also revealed reduced suitability of larger streams greater distances from groundwater springs, the same streams frequently occupied by non‐native Channel catfish. A general pattern of increased use of streams draining watersheds with altered or developed land uses was apparent. Assessment of introgression and hybridization with non‐native channel catfish at nine locations showed evidence of ongoing or past hybridization at six locations. Persistence of potentially non‐introgressed populations were found at three locations with smaller sample sizes.
Main conclusions
Modelling temporal changes in Headwater catfish distribution provided critical insight into the types and locations of streams that should be targeted for habitat preservation or restoration. Conservation and management of Headwater catfish will require priority decisions based on existing levels of introgression and the practicality of preventing further contact with Channel catfish. Maintaining Headwater catfish populations in springs that are also heavily used by humans will be critical for conservation of the species in the United States.
... For example, global data sets of watershed boundaries and sub-basin delineations are now available to support planning and prioritization efforts at global scales (e.g., HydroSHEDS, Linke et al., 2019). They allow for analysis of up-and downstream connectivity (Allan et al., 2019;Hermoso et al., 2012). Multiple tools that assist both understanding and modelling runoff regimes are available, even for data-poor regions (Brown et al., 2019). ...
There is a growing recognition that conservation strategies should be designed accounting for cross-realm connections, such as freshwater connections to land and sea, to ensure effectiveness of marine spatial protection and minimize perverse outcomes of changing land-use. Yet, examples of integration across realms are relatively scarce, with most targeting priorities in a single realm, such as marine or freshwater, while minimizing threats originating in terrestrial ecosystems. To date, no study has optimized priorities across multiple realms to produce a spatially explicit integrated conservation plan that simultaneously accounts for multiple human activities at a national scale. This represents a major gap in the application of existing cross-realm planning theory. We present a national scale conservation framework for selecting protected areas using a case study of Papua New Guinea (PNG) that integrates multiple systems and ecological connectivity to account for cross-realm benefits and minimize threats of land-use and climate change. The relative importance of both the forests and inshore reef environments to PNG subsistence and commercial livelihoods emphasizes the importance of considering the connections between the land and sea. The plan was commissioned by the PNG Conservation and Environment Protection Authority and identifies a comprehensive set of priorities that meet conservation targets in both the land and sea. Our national-scale prioritization framework is useful for agencies and managers looking to implement actions given multiple objectives, including watershed management and biodiversity protection, and ensures actions are efficient and effective across the land and sea.
... Effective conservation of riverine biodiversity is challenging, and there is an opportunity to enhance the effectiveness of conservation planning by extending a framework initially designed for other landscapes (Hermoso et al., 2012). For example, dendritic habitatnetworks (e.g., those with a tree-like structure) complicate the understanding of how landscape connectivity acts in the fluvial ecosystems (Linke et al., 2011;Kuemmerlen et al., 2019) in at least by two aspects. ...
The ability to prioritize habitats that have spatially varied contributions to species persistence can produce synergistic benefits for regional conservation efforts. However, conservation in spatially diverse landscape-networks requires considering dispersal asymmetry in the context of ecological connectivity and metapopulation persistence. By developing an approach based on metapopulation theory, this study prioritized the importance of habitat (as determined by the habitat quality and spatial position in networks) on metapopulation structure in mountainous streams. As a case study, we examined dispersal via overland and instream networks in a riverine mayfly Rhithrogena sp. cf. japonica in a mountain range of Southwest China. Compared to flow velocity, water depth, and instream nutrient-levels, water temperature was a key factor in determining local habitat suitability for R. sp. cf. japonica. Higher water temperature was linked to poor habitat suitability. Instream pathways were the main dispersal corridors compared with overland movement between tributaries for this mayfly. In basins on the east aspect of this mountain range, either monotonically increasing (i.e., never decreasing) or unimodal (i.e., with a single peak) patterns demonstrated the importance of riverine habitats that occur along elevational gradients. However, the importance of habitat appeared to show no definite patterns with elevation on the west aspect. In terms of metapopulation structure, local quality of habitat contributed more to the regional importance of habitat than its spatial position in the networks. The framework presented highlights that the importance of riverine habitats may be quite variable in species having directional dispersal networks across the fluvial landscape in mountainous areas. Results from this framework can serve as the basis to apply a mechanistic understanding to managing and protecting native populations through regional restoration actions.
... Coupling this with mapping wetland hydrology (e.g. Nel et al., 2011) can inform water resource management, efficiently accounting for longitudinal, lateral and vertical connectivity, critical for systematic conservation planning of freshwater ecosystems (Sheldon et al., 2002;Linke et al., 2008;Hermoso et al., 2012). This is important for low-relief rivers and wetlands, connected laterally during floods or isolated from the major rivers (Kingsford et al., 2001;Kingsford and Lee, 2010;Thomas et al., 2015). ...
Rivers and wetlands are under considerable threat around the world from climate
change, pollution, invasive species and overharvesting of water. Such complex
problems demand development of tools to improve wetland management and
recognize their ecological and ecosystem service values. Understanding the interrelationships between freshwater ecosystems and human uses necessitates
analyses of water resources at large spatial and long temporal scales, possible
using classification of satellite imagery. The inundation regime directly influences
wetland type, critical for understanding long-term trajectories of change which
affect the ecosystem. Landsat optical imagery is routinely used to map inundation
and wetlands across Australia, but cannot penetrate cloud cover or vegetation to
detect all inundated areas. Contrastingly, synthetic aperture radar (SAR) imagery
overcomes these shortcomings, but remains largely untested for arid areas. To
address this gap in knowledge, I tested the effectiveness of using L-band SAR to
map inundation and wetland types in the Paroo and Warrego River floodplains
within the Murray-Darling Basin, arid Australia. Data from the Japanese Advanced
Land Observing Satellite (ALOS) Phase Arrayed L-band SAR (PALSAR) sensor were
provided through the Kyoto & Carbon (K&C) Initiative to meet requirements of the
RAMSAR convention on wetlands. I successfully detected inundation in arid land
cover types using segmentation and change detection of SAR L-HH/HV data to high
accuracy. I used SAR data mining in a classification and regression tree analysis to
differentiate arid wetland types with a high accuracy, validated with field data.
Overall, the use of L-band SAR satellite data was effective for rapid flood mapping
and discrimination of different vegetated wetlands, and clearly has wider
applicability. I then investigated the flooding regime of the largest floodplain
iii
wetland in the system, Yantabulla Swamp, by mapping inundation using a
combination of ALOS PALSAR, Landsat, and aerial surveys; obtaining historic river
flow records, local rainfall and evaporation data; and modelling flood volume to
hindcast flooding regime over 4.5 decades (1970-2015). Yantabulla Swamp has a
highly variable inundation regime. On average, large episodic ‘boom’ events (>90%
extent) occurred about every 3.1 years, medium-high events (>40%) every 1.6
years, medium-low events (<40%) every year, with a mean flood extent of 14.82%
(SD=25.57). Some years were dry while others had multiple low spells within a year
and the longest period between episodic (>90%) events was 7.21 years, reflecting
the unpredictability of the system. Rainfall contributed occasionally as the sole
contributor to some low extent events, while a combination of rainfall and flow
from Paroo River and Cuttaburra Creek produced the largest and longest events.
Overall there was a higher mean rate of rise (1.67%/day) compared to fall
(0.33%/day) for individual events, showing slower recession. The combination of
SAR and Landsat data successfully enabled modelling to characterise multidecadal inundation regimes of Yantabulla Swamp.
... La connectivité spatio-temporelle joue un rôle clé dans le maintien d'importants processus écologiques (Ward, 1989), comme la dispersion, les flux génétiques ou le transport d'énergie et de matière, essentiels à la persistance des populations et des espèces. Des exemples sont disponibles de la façon d'intégrer efficacement la connectivité dans toutes ses dimensions : longitudinale (Hermoso et al., 2011), latérale (Hermoso et al., 2012a), verticale (Nel et al., 2011) et temporelle (Hermoso et al., 2012b), dans des cadres de planification systématique de la conservation, qui aideront à concevoir des aires protégées écologiquement fonctionnelles du point de vue de l'eau douce. Des progrès ont également été réalisés dans l'intégration des menaces et des processus de dégradation dans la planification de la conservation, afin d'éviter les efforts de conservation dans des zones où l'existence de menaces ou leur propagation pourrait compromettre la persistance de la biodiversité (par exemple, Moilanen et al., 2011 ;Linke et al., 2012). ...
... This allows the union of river conservation management with river connectivity. River connectivity and ecological value must be assessed together to achieve efficient river area conservation (Hermoso et al., 2017(Hermoso et al., , 2012. It is also necessary to remember that connectivity indices do not assess other profound dam impacts, such as erosion, lack of sediment and nutrient transport, the facilitation of exotic species invasions or hydrological regime changes, which have to be considered in river conservation plans (Clavero and Hermoso, 2011;Liermann et al., 2012;Timpe and Kaplan, 2017). ...
Different indices have been developed to quantify the extent and severity of river fragmentation. These indices vary depending on the specific goals of the study. Here, we present a new Conservation Connectivity Index (CCIP) for potamodromous fish species that considers the conservation value (richness, rarity and vulnerability) of river segments.
The Iberian Peninsula holds > 20 endemic and endangered potamodromous fish species as well as > 1000 large dams (> 1 hm³ of capacity). The CCIP was calculated for the eight most important river basins of the Iberian Peninsula and compared to the Dendritic Connectivity Index (DCIP) developed by Cote et al. in 2009, which uses only river length as a habitat variable. With the use of both DCIP and CCIP, the dams were analysed and ranked according to their impacts on the river basin.
The main results show that Iberian river basins are heavily fragmented, with river basin connectivity percentages of less than 20% in most cases using both DCIP and CCIP. CCIP values are slightly higher than DCIP values in almost all cases. When the impact of individual dams is analysed, differences also appear between the DCIP and CCIP. CCIP highlights the impact of dams located in areas of high fish conservation value while DCIP emphasize the impact of dams fragmenting large river segments.
The CCIP appears to be adequate to highlight important sites for conservation in river connectivity studies. It could be applied in different studies and river basins around the world to prioritize dam removals or plan new dam locations.
... We identified priority areas for conservation within the lesser prairie-chicken range in Kansas using the decision-support software Marxan (Ball et al. 2009). We used Marxan to identify areas to prioritize for conservation by finding the optimal set of planning units that minimized the following objective function: Fig. 2 Map of the ecologically important areas used to constrain planning unit selection in a Scenario 1, where the focal areas and connectivity zones (CHAT categories 1 and 2) were prioritized and other areas modeled as potential habitat (CHAT category 3) secondarily considered, b Scenario 2, where all areas modeled as potential habitat (CHAT categories 1, 2, and 3) were equally prioritized, and c Scenario 3, where areas within 10 km of known lek locations were prioritized where PUs were planning units, cost was the defined cost for selecting a specific planning unit for conservation prioritization, BLM was the boundary length modifier, a multiplicative factor used to control the relative importance of planning unit connectivity and allow for compatibility between different metrics, boundary was the outer boundary of the selected planning units, SPF was the species penalty factor, a multiplicative factor used to control the relative importance of meeting conservation targets (CTs) and allow for compatibility between different metrics, and penalty was the proportion of each conservation target not met in the solution (Game and Grantham 2008;Ball et al. 2009;Hermoso et al. 2012). Marxan thus used this objective function to select a combination of planning units that met all conservation targets, was configured to achieve high connectivity, and had a minimal cost. ...
ContextDevelopment of systematic methods for conservation planning has improved effectiveness and efficiency of implementing such plans. The lesser prairie-chicken (Tympanuchus pallidicinctus) is a grouse species of conservation concern native to the southwestern Great Plains of the United States. Recent lesser prairie-chicken conservation planning has involved identifying ecologically important areas but has not incorporated economic data into prioritization of areas to target for conservation management.Objectives
We used the program Marxan to develop a decision-support tool for managers in Kansas to prioritize tracts for improving lesser prairie-chicken habitat quality and increasing habitat availability. We developed three different conservation scenarios and evaluated the tradeoffs among multiple planning objectives in these scenarios.Methods
We incorporated population targets from an existing conservation plan and agricultural economic data to help select land with maximum ecological value and minimum economic productivity to prioritize for lesser prairie-chicken conservation. We compared potential conservation plans and incorporated a post hoc connectivity model to test potential for individuals to travel among habitat patches in these plans during dispersal events.ResultsWe found that different conservation scenarios led to different solutions, though differences varied by ecoregion. Potential solutions for all scenarios contained habitat patches not currently included in existing conservation plans and had high connectivity potential.Conclusions
These results provide context for spatial prioritization of lesser prairie-chicken habitat management in Kansas. Application of this approach to species of conservation interest could help managers incorporate socioeconomic factors into planning methods and identify important tracts for conservation currently overlooked by existing planning methods.
Ecological connectivity is key to maintaining a coherent and resilient network of protected areas in the EU. The EU Biodiversity Strategy for 2030 has identified the unhindered movement of species, nutrients and ecological processes across connected landscapes as a key feature of a coherent Trans-European Nature Network (TEN-N) of protected and conserved areas. However, to date, streamlined guidance on planning for and implementing connectivity measures specifically at the European scale has been limited.
This report presents a coherent methodological framework and guidelines for mapping functional and structural connectivity at the European scale, as part of the Horizon Europe NaturaConnect project, which is supporting EU Member States in developing a coherent TEN-N of protected and conserved areas.
It describes key ecological connectivity concepts and approaches; outlines methods and tools for estimating connectivity; presents an overview of connectivity projects across Europe; identifies connectivity priorities, gaps and challenges following a stakeholder consultation process; and provides practical and operational guidelines for implementing ecological connectivity for conservation projects ranging from regional to national and European levels. The guidelines present a strategic blueprint aimed at enhancing ecological connectivity across Europe, and address the specific challenges and opportunities related to planning ecological connectivity in the European context.
This report has been written for practitioners and individuals involved in the management and administration of protected areas and ecological connectivity projects across Europe. This includes professionals working in TEN-N implementation at national or regional levels, others involved in spatial planning outside protected areas, and professionals engaged in the implementation of connectivity projects and protected area management.
India boasts of a vast freshwater resource network (rivers, wetlands, and groundwater), which has unique ecological, social and economic values associated with it. Despite their importance for both people and biodiversity, its freshwater ecosystems (FWEs) are heavily impacted through multiple factors such as pollution, overexploitation, habitat loss/modification and climate change. India is also among the hotspots of water resource overuse that has caused a serious decline in freshwater availability.
Given that healthy FWEs lie at the centre for supporting the country's ecology, health, economy, livelihoods and ultimately achieving multiple policy goals, it is crucial that holistic and focused efforts are made to protect, conserve, and restore all types of FWEs.
We call for an urgent and a greater focus on implementing conservation actions for FWEs in India and suggest the following strategy to enhance focus on their conservation: (1) establishing a shared freshwater conservation vision at a national scale, (2) developing and including national freshwater conservation goals within global efforts, (3) conducting simultaneous conservation action planning at regional scales and (4) bridge planning to implementation gap by strengthening key enabling conditions: i) mainstream FWE conservation within key existing governance instruments, ii) secure sustainable conservation funding, iii) improve data access and knowledge translation; iv) create national awareness around importance of FWEs; v) facilitate collaboration among key actors.
Very little has been achieved during the first five decades of development and application of what is now known as environmental law, in terms of slowing the global rate of biodiversity loss and ecosystem degradation. A major factor in this lack of effectiveness has been, perhaps, too narrow a focus on individual elements that exist within ecosystems, rather than on the health of the ecosystems themselves. Additionally, very little attention has been paid to maintenance of the integrity of the many types of connections that exist between the different components of ecosystems, notably aquatic ecosystems. These components are connected not only by water, but also by a variety of ecological connections and pathways 3⁄4 here termed 'hydroecological connectivity' (HEC). These connections are not only important in terms of providing abiotic and biota corridors between components, but they also act as conduits which can translocate pollutants from one location, over vast distances, throughout a fluvial ecosystem, consequently impacting virtually all areas of human life and nature.
This thesis outlines the science underpinning the first connectivity-based water law regulation, the American Clean Water Rule (CWR) and analyzes a set of legal challenges to this Rule. Barring one instance, no substantive merit was found for any of the disputed claims. Furthermore, this thesis identifies the transferability of the Rule to South Africa. It was possible to empirically substantiate the merit of the single instance that lacked appropriate qualification in the CWR.
The importance of HEC is elucidated in this work using the example of headwater streams which, in aggregate, comprise 79 per cent of the aggregate length of the mapped rivers in South Africa. Also provisionally evaluated is a brightline distance, lateral to fluvial watercourses, within which water resource components that are likely to be connected to the mainstem will be found. This provides a guideline for HEC-directed administrative decision making.
A connectivity-based approach to water resource governance will require limitations on some land uses on portions of land that is likely to be perceived as terrestrial but which, in fact, forms part of an aquatic ecosystem. This requirement raises obvious implications for property ownership and expropriation. Here the principles of the public trust, already legislatively expressed in South African water law, provide an institutional legal framework that renders 'public' any lands which form part and parcel of the integrity an aquatic ecosystem.
ii
The public trust doctrine anchored the reform of the post-apartheid water law of South Africa. It was introduced in a transformative and emancipatory approach to the democratisation of the nation's water resources and the restoration of water equity. This work provides the first historico-legal and comprehensive perspective of the genealogy and intentions for, the public trust in South Africa, and distils out the principles which the trust embodies. An example protocol is developed which shows how the trust principles underpin the formulation of guidance for determinations of beneficial water uses.
Recommendations are made regarding the operationalization of the currently moribund South African public trust in water and highlights the role of the public trust as an effective and reformatory tool of water law.
In summary this work is a translational and transdisciplinary example of aquatic science into environmental law. The complex and challenging concept of HEC is communicated in plain language and then its perceived weak point 3⁄4 the need to isolate areas of land which form part of the aquatic resource and incorporate these within the trust res 3⁄4 is construed using the principles of the public trust doctrine. Simultaneously the potential of the public trust to offset obstacles to environmental protection, such as the need for reformed guidance for administrative decision making, has been highlighted. On this model the public trust enfolds an ecosystem-directed HEC approach into a transformative and normative governance package which is integrative, adaptive, multi-disciplinary and proactive.
In light of the ongoing freshwater biodiversity crisis, detailed knowledge regarding the spatial distribution of freshwater species is urgently required, especially in biodiversity hotspots. Here we present a database of georeferenced occurrence records of four freshwater invertebrate taxa groups across Cuba, namely flatworms (Platyhelminthes: Tricladida), insects (Ephemeroptera, Odonata, Hemiptera, Trichoptera, Coleoptera, Diptera), crabs and shrimps (Crustacea: Decapoda), and mollusks (Mollusca). We collated the geographic occurrence information from scientific literature, unpublished field records, museum collections and online databases. The database, comprising 6292 records of 457 species at 1075 unique localities, is organized in 32 fields that contain the information about the taxonomic classification of each recorded species, the sex and life stage of collected individuals; the geographic coordinates, location, author and date of the record and a reference to the original data source. This database provides an important basis towards an improved understanding of the spatial distribution of freshwater biodiversity in Cuba.
Species conservation often faces many challenges, such as addressing threats from multiple stressor sources, representing under-studied taxa, and understanding implications of spatial extent. To overcome these challenges, we assessed contemporary anthropogenic threats from stream fragmentation and landscape disturbance as well as future habitat suitability under climate change for traditionally well-studied (fishes) and under-studied (mussels) imperiled fluvial taxa in Michigan, USA. To understand how threats to species vary spatially, predicted habitat suitability was analyzed for three hierarchically nested spatial extents: statewide, within species’ biogeographic ranges, and within river patches fragmented by barriers. Comparison of current and future habitat suitability for 27 fish and 23 mussel species indicates large potential statewide gains for many warmwater and/or large river fishes and several mussel species, however these gains are greatly diminished by biogeographic range limitations and habitat fragmentation among current and future habitats. One mussel species and several cold- and coolwater fishes are projected to have significant habitat losses under climate change irrespective of spatial extent. On average, 79% of habitats for mussels and 58% for fishes were considered moderately to severely disturbed from current human landscape activities. Habitat fragmentation was greater for fishes than mussels, with large dams playing a primary role in fragmenting habitats relative to small dams and waterfalls. Results indicate that threat assessments can vary substantially according to spatial extent and taxa, and consideration of both contemporary and future threats to habitats is needed to inform conservation of imperiled fluvial organisms.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The book includes the first global assessment of the number, type and distribution of threatened freshwater fish species, discussing the features of freshwater fish biology and ecology that render so many species vulnerable to extinction. Introductory chapters on why freshwater fish are so sensitive to environmental change and disturbance lead into chapters providing detailed reviews of the key threatening processes and potential solutions. A concluding chapter summarises the key issues and looks to the future for opportunities and challenges for the conservation and management of freshwater fish.
Conservation biology has historically been based on principles to protect terrestrial ecosystems, with marine and freshwater ecosystems left behind. As a result, often, protected areas are defined with bases in forest cover and terrestrial characteristics overseeing important components of connectivity of riverine landscapes, such as the connectivity between rivers, lakes, and streams. It is important to emphasize that forest protection is extremely important, but that alone cannot safeguard the protection of freshwater ecosystems. Therefore, our discussion should lead, not to the disregard of terrestrial efforts but to the complementation of existing efforts for forest protection with the addition of areas that can also protect freshwater ecosystems. Fluvial ecosystems are hierarchical and nested systems, with multidimensional connectivity including longitudinal (upstream-downstream), lateral (floodplains and lakes), temporal (seasons) and vertical (groundwaters) connections. Systematic Conservation Planning (SCP) is the most well accepted and used method for designing conservation plans based on cost-effective scenarios that include ecological and socio-economic values resulting in thematic maps of priority areas for conservation. Recently, methods to consider the connectivity of freshwater ecosystems were incorporated into spatial prioritization tools. Maps produced using spatial prioritization tools can help decision making on species management and conservation actions, such as plans for species’ impact reduction (PRIM) and action plans for threatened species (PAN). PRIM and PAN use information about species ecology to focus conservation actions onto target species. These conservation action plans must be viable not only ecologically but also economically. In this context, using SCP to guide designs of PRIM and PAN can help stakeholders to achieve better conservation actions in Brazil. Thus, the SCP can improve the conservation and management of freshwater ecosystems, through the integration of science, society and stakeholder.
1. Systematic conservation planning in freshwater ecosystems faces multiple challenges because of the dynamic nature of rivers and their multiple dimensions of connectivity. In intermittent hydrological systems connectivity is functional when water is available, allowing the exchange of aquatic individuals between isolated freshwater ecosystems. Integrating these isolated systems in their hydrological context is essential when identifying priority areas for conservation,
in order to try to minimize the propagation of threats into target water bodies (management units) from the surrounding landscape.
2. Here, the use of a systematic planning approach is demonstrated to identify a set of priority management units to preserve freshwater biodiversity in an arid system of fragmented water bodies immersed in a landscape subject to a range of impacts.
3. Twenty-six water-dependent taxa from 59 mountain rock pools (gueltas) of three southern Mauritanian mountains were used as a case study. A conservation planning tool (MARXAN) was used to find priority conservation areas to integrate intermittent hydrological systems in their hydrological context, promote connectivity, and minimize the downstream propagation of threats. Three types of connectivity were analysed: (i) no connectivity, (ii) connectivity between gueltas, and (iii) connectivity between gueltas and sub-catchments.
4. Considering different types of longitudinal connectivity affects the number and spatial allocation of the priority gueltas selected, and the conservation status of the gueltas and their upstream areas. Incorporating connections between gueltas and upstream locations in the modelling resulted in the selection of gueltas in areas with a low human footprint and in the increased connectivity of the solutions.
5. The results obtained revealed important locations for local biodiversity conservation, and the method presented can be used when assessing the propagation of potential waterborne threats into isolated management units. The framework developed allows connectivity to be addressed in conservation planning. It can be replicated in regions with similar isolated habitats that connect through intermittent hydrological systems and can also be applied to lateral and vertical hydrological connectivity.
Connectivity plays a key role in biodiversity conservation as it sustains ecological processes, such as migrations, important for the maintenance of populations. Connectivity is especially relevant for species that rely on different realms during their life cycle or use different realms daily or seasonally (multi‐realm species). However, efforts to address conservation across multiple realms have focused on identifying priority areas for conservation in a single realm (mostly marine) while accounting for threats propagating from other realms or single species needs.
Here, we demonstrate how to identify priority areas for conservation across three different realms (freshwater–terrestrial, estuary and marine) for multiple species, including some multi‐realm species, that inhabit or move across the three realms, using the Tagus River (Western Iberian Peninsula), its estuary and nearby marine area as a case study. We integrated multiple types of connectivity in the selection of priority areas for conservation, each of them customised to depict important drivers of movement within each realm and across realms: longitudinal connectivity along rivers or multidimensional connectivity in the estuary and marine realms, guided by currents and depth similarity, respectively. We compared the allocation of priority areas and spatial connectivity achieved under three scenarios: no‐connectivity, within‐realm and cross‐realm connectivity scenarios.
There were differences in the spatial allocation of priority areas across scenarios. The most remarkable difference laid on the connectivity achieved under each scenario, which experienced a threefold increase when considering connectivity across realms, compared to solutions that considered only connectivity within each realm independently. This improvement in connectivity was especially marked for species that occur across different realms. There were, however, trade‐offs between this improvement in connectivity and the increase in the number of planning units selected, especially in the estuary.
Synthesis and applications. Addressing connectivity across realms deserves special attention when planning for the conservation of multi‐realm species to ensure the adequacy of conservation recommendations to respond to the needs of multi‐realm species. Given the potential trade‐offs between enhanced cross‐realm connectivity and total area needed or internal within‐realm connectivity, consideration of cross‐realm connectivity must be cautiously evaluated and integrated in multi‐realm conservation plans.
Key messages:
• Five high level ecological principles common to all freshwater ecosystems are presented. Although they have different ramifications for each ecosystem type these principles are fundamental to the design and management of all freshwater Protected Areas (PAs) and the conservation of aquatic
biodiversity.
• A universal guiding principle for PA management is that the entire catchment with its land, water, biogeochemical resources and processes is the ideal unit to be protected and managed. Where full protection is not possible, the catchment needs to be managed in a sustainable way that minimises threats
and impacts from non-reserved lands. Protected area management that fails to recognise and address the threats and pressures arising in the catchment risks loss of environmental quality, species diversity and ecological resilience.
• The flow of water is one of five dynamic environmental regimes that regulate much of the structure and functioning of every running water ecosystem and many aspects of lentic and groundwater systems. The naturally dynamic flow regime plays a critical role in sustaining native biodiversity and ecosystem integrity in streams and rivers. Likewise the characteristics
and variability of lentic (lakes and estuaries) and subsurface water regimes are critical to their dynamics, management and conservation.
• The spatial and temporal connectivity patterns and processes of aquatic ecosystems in their natural state are important elements for consideration in PA design and management. Connectivity in rivers is defined in three spatial dimensions: longitudinal (upstream–downstream), lateral (interactions between channel and riparian/floodplain systems), and vertical (connections between the surface and groundwater systems), with temporal dynamics influencing all spatial dimensions of connectivity. Thus minimising the impacts of dams and levee banks as barriers, and changes to water flows, is crucial for conservation. The hydrological connectivity between lakes, streams, estuaries and subsurface environments also requires special attention in PA design and management, and forms a central pillar of Integrated Lake Basin Management (ILBM).
• A primary goal of biodiversity conservation is to delineate PAs that conserve species-rich habitats and vital resources, important species radiations and the greatest number of threatened endemic species. Significant interbasin differences in biodiversity and levels of endemism mean a lack of ‘substitutability’ among freshwater habitat units, adding to the complexity of freshwater biodiversity conservation. The tools of systematic conservation planning lend themselves to identification of the most beneficial options for biodiversity protection.
•Freshwater species have long histories of exposure and adaptation to variable environmental conditions and extremes (e.g., drought and flood cycles), conferring resistance and resilience at the individual, community and ecosystems levels. Maintaining catchment integrity, natural flow and standing water regimes, the spatial and temporal dimensions of connectivity,
and native biodiversity hotspots will help to maintain the ecological resilience of aquatic systems in protected areas, and support societal adaptations to shifting environmental and climatic regimes.
The conservation movement “Nature Needs Half” (NNH) aims to protect 50% of the earth by 2050. But increase in total protected area (PA) coverage alone does not guarantee adequate species protection, and identifying conservation priority areas that meet specific species conservation targets is suggested as a way forward. Further, PAs are dynamic entities and the loss event termed protected area downgrading, downsizing and degazettement (PADDD) can hamper efficacy of PAs in biodiversity conservation. Considering known threats to both biodiversity and PAs during systematic conservation planning can help identify robust conservation priority areas. Bhutan, a country that already achieved the NNH target through terrestrial-focused PAs and with hydropower as main cause of PADDD, provides a unique case study. We identify freshwater priority areas for Bhutan using Marxan, a widely used systematic conservation planning tool. We assessed two different Marxan scenarios: scenario 1 did not exclude planning units with hydropower sites during planning and scenario 2 excluded them. We found using freshwater species and forest types as conservation features during conservation planning afforded better protection to the species and forest types by the reserves over that by the existing PA system, though the reserves and existing PA system had similar total area. Further, the reserve from the scenario 2 provided similar protection to the freshwater species and forest types as to that provided by the reserve from scenario 1. Our findings suggest need to consider target species and known threats during conservation planning stage to better protect biodiversity even within NNH paradigm.
Cet article propose une analyse historique critique du développement du droit international de l’environnement. Il vise à présenter les idéologies qui sont au coeur du projet du droit international de façon plus générale et du droit international de l’environnement en particulier qui font en sorte que ce droit offre peu de solutions pour protéger l’environnement. L’analyse est effectuée en quatre temps. D’abord, l’article se concentre sur la conception influencée par le libéralisme classique de la nature dans le droit international général, en particulier quant au traitement des pêcheries avant que le droit international de l’environnement en tant que discipline distincte émerge dans les années 1970. Ensuite, l’article se tourne vers la naissance de certaines préoccupations environnementales dans le droit international après la Deuxième Guerre mondiale, alors que le droit s’intéresse notamment à la pollution des mers. Durant cette deuxième période, le droit international prend une tangente providentialiste pour s’intéresser aux problèmes environnementaux, mais sans changement notable sur la conception libérale classique de la nature au sein du droit international. Puis, vient le droit international de l’environnement en tant que domaine distinct du droit international dans les années 1970 et 1990. Ce nouveau domaine de droit qui se développe alors s’inscrit en continuité avec les principes libéraux du droit international général, mais il est également influencé par le néolibéralisme en plein essor durant cette période. Finalement et face aux échecs du droit international de l’environnement à résoudre les problèmes pour lesquels il est adopté, l’article présente la Green Legal Theory, une approche critique du droit qui donne certaines pistes pour mener à une révolution du droit de l’environnement.
The current conservation crisis calls for research and management to be carried out on a long-term, multi-species basis at large spatial scales. Unfortunately, scientists, managers, and agencies often are stymied in their effort to conduct these large-scale studies because of a lack of appropriate technology, methodology, and funding. This issue is of particular concern in wetland conservation, for which the standard landscape approach may include consideration of a large tract of land but fail to incorporate the suite of wetland sites frequently used by highly mobile organisms such as waterbirds (e.g., shorebirds, wading birds, waterfowl). Typically, these species have population dynamics that require use of multiple wetlands, but this aspect of their life history has often been ignored in planning for their conservation. We outline theoretical, empirical, modeling, and planning problems associated with this issue and suggest solutions to some current obstacles. These solutions represent a tradeoff between typical in-depth single-species studies and more generic multi-species studies. They include studying within- and among-season movements of waterbirds on a spatial scale appropriate to both widely dispersing and more stationary species; multi-species censuses at multiple sites; further development and use of technology such as satellite transmitters and population-specific molecular markers; development of spatially explicit population models that consider within-season movements of waterbirds; and recognition from funding agencies that landscape-level issues cannot adequately be addressed without support for these types of studies.
Freshwater habitats occupy ,1% of the Earth's surface, yet are hotspots that support ,10% of all known species, and ,M of vertebrate species. Fresh waters also are hotspots for human activities that have led to widespread habitat degradation, pollution, flow regulation and water extraction, fisheries overexploitation, and alien species introductions. These impacts have caused severe declines in the range and abundance of many freshwater species, so that they are now far more imperiled than their marine or terrestrial counterparts. Here, we review progress in conservation of freshwater biodiversity, with a focus on the period since 1986, and outline key challenges for the future. Driven by rising conservation concerns, freshwater ecologists have conducted a great deal of research over the past 25 y on the status, trends, autecology, and propagation of imperiled species, threats to these species, the consequences of biodiversity loss for ecosystem functioning, metapopulation dynamics, biodiversity hotspots, reserve design, habitat restoration, communication with stakeholders, and weaknesses of protective legislation. Nevertheless, existing efforts might be insufficient to stem the ongoing and coming multitude of freshwater extinctions. We briefly discuss 4 important challenges for freshwater conservation. First, climate change will imperil both freshwater species and human uses of fresh water, driving engineering responses that will further threaten the freshwater biota. We need to anticipate both ecological and human responses to climate change, and to encourage rational and deliberate planning of engineering responses to climate change before disasters strike. Second, because freshwater extinctions are already well underway, freshwater conservationists must be prepared to act now to prevent further losses, even if our knowledge is incomplete, and engage more effectively with other stakeholders. Third, we need to bridge the gap between freshwater ecology and conservation biology. Fourth, we suggest that scientific societies and scholarly journals concerned with limnology or freshwater sciences need to improve their historically poor record in publishing important papers and influencing practice in conservation ecology. Failure to meet these challenges will lead to the extinction or impoverishment of the very subjects of our research.
Introduction If you leave the Wet Tropics around Cairns, and head west by car for an hour or so, the road goes up and over the mountains that lie behind the coast. On the other side, the rainfall drops off quickly, and you enter the great ‘sea’ of savanna that stretches across Northern Australia. Still heading west, several long days of driving later, you will reach Broome on the edge of the Indian Ocean. For all this time, for all the 3000 or more kilometres of travel, you will have been among vast areas of eucalypt savannas and native grasslands, broken only by an occasional cleared paddock, a scattering of small towns, and the rivers and wetlands that give life to the country. This landscape of savanna and rainforest, rivers and wetlands, is of great significance. On a global scale, such large natural areas are now very rare. Northern Australia stands out as one of the few very large natural areas remaining on Earth: alongside such global treasures as the Amazon rainforests, the boreal conifer forests of Alaska, and the polar wilderness of Antarctica. Unlike much of southern and eastern Australia, nature remains in abundance in the North. Great flocks of birds still move over the land searching for nectar, seeds and fruit. Rivers still flow naturally. Floods come and go. In fertile billabongs, thousands of Magpie Geese, brolgas, egrets and other water birds still congregate. The intact nature of the North provides a basis for much of the economic activity and the general quality of life for residents of the area. Most of the major industries – tourism, pastoralism, Indigenous economies – rely on productive, functioning and healthy natural ecosystems. Across the North, recreational activities such as fishing, four-wheel driving and visiting beautiful country depend on the opportunities provided by a largely intact and natural landscape. Being in and among nature remains a normal part of life for people in the North, in contrast to the situation for those living in the now highly transformed, cleared and urbanised areas of southern Australia. For the high proportion of Northern Australian residents who are Indigenous, country is part of the essence of life. Knowledge of and links to the land remain strong, and there remains an enduring responsibility to look after the land, and its plants and animals.
Knowledge of the patterns of movement of tropical waterfowl should assist in long-term conservation of these birds and their wetlands. Data that indicate or suggest the extent of connectivity between populations help us to make decisions, particularly when those populations are threatened by loss and fragmentation of habitat. To date, there has been little research on tropical waterfowl, with most work on this group of birds done in temperate regions. We tracked the seasonal movements of 10 Magpie Geese (Anseranas semipalmata) in tropical northern Australia, predominantly within Kakadu National Park, using satellite telemetry. Movements were multi-directional and the maximum linear distance travelled by an individual was 114 km from the site of release, over 38 weeks of tracking. Movements did appear to be related to seasonal environmental fluctuations, with some birds moving to favoured breeding and foraging sites, but most monitored birds were resident within the national park. No accurate data were obtained beyond 12 months, with most birds apparently losing their telemeters within 6 months. Just 62% of point-location data were accurate to within 1000 m. Our work provides further ecological data on a species threatened by sea-level rise and important to Aboriginal and recreational hunters.
Running waters are perhaps the most impacted ecosystem on the planet as they have been the focus for human settlement and are heavily exploited for water supplies, irrigation, electricity generation, and waste disposal. Lotic systems also have an intimate contact with their catchments and so land-use alterations affect them directly. Here long-term trends in the factors that currently impact running waters are reviewed with the aim of predicting what the main threats to rivers will be in the year 2025. The main ultimate factors forcing change in running waters (ecosystem destruction, physical habitat and water chemistry alteration, and the direct addition or removal of species) stem from proximate influences from urbanization, industry, land-use change and water-course alterations. Any one river is likely to be subjected to several types of impact, and the management of impacts on lotic systems is complicated by numerous links between different forms of anthropogenic effect. Long-term trends for different impacts vary. Concentrations of chemical pollutants such as toxins and nutrients have increased in rivers in developed countries over the past century, with recent reductions for some pollutants (e.g. metals, organic toxicants, acidification), and continued increases in others (e.g. nutrients); there are no long-term chemical data for developing countries. Dam construction increased rapidly during the twentieth century, peaking in the 1970s, and the number of reservoirs has stabilized since this time, whereas the transfer of exotic species between lotic systems continues to increase. Hence, there have been some success stories in the attempts to reduce the impacts from anthropogenic impacts in developed nations. Improvements in the pH status of running waters should continue with lower sulphurous emissions, although emissions of nitrous oxides are set to continue under current legislation and will continue to contribute to acidification and nutrient loadings. Climate change also will impact running waters through alterations in hydrology and thermal regimes, although precise predictions are problematic; effects are likely to vary between regions and to operate alongside rather than override those from other impacts. Effects from climate change may be more extreme over longer time scales (>50 years). The overriding pressure on running water ecosystems up to 2025 will stem from the predicted increase in the human population, with concomitant increases in urban development, industry, agricultural activities and water abstraction, diversion and damming. Future degradation could be substantial and rapid (c. 10 years) and will be concentrated in those areas of the world where resources for conservation are most limited and knowledge of lotic ecosystems most incomplete; damage will centre on lowland rivers, which are also relatively poorly studied. Changes in management practices and public awareness do appear to be benefiting running water ecosystems in developed countries, and could underpin conservation strategies in developing countries if they were implemented in a relevant way.
1. In this review, we first summarize how hydrologic connectivity has been studied for riverine fish capable of moving long distances, and then identify research opportunities that have clear conservation significance. Migratory species, such as anadromous salmonids, are good model organisms for understanding ecological connectivity in rivers because the spatial scale over which movements occur among freshwater habitats is large enough to be easily observed with available techniques; they are often economically or culturally valuable with habitats that can be easily fragmented by human activities; and they integrate landscape conditions from multiple surrounding catchment(s) with in‐river conditions. Studies have focussed on three themes: (i) relatively stable connections (connections controlled by processes that act over broad spatio‐temporal scales >1000 km ² and >100 years); (ii) dynamic connections (connections controlled by processes acting over fine to moderate spatio‐temporal scales ∼1–1000 km ² and <1–100 years); and (iii) anthropogenic influences on hydrologic connectivity, including actions that disrupt or enhance natural connections experienced by fish.
2. We outline eight challenges to understanding the role of connectivity in riverine fish ecology, organized under three foci: (i) addressing the constraints of river structure; (ii) embracing temporal complexity in hydrologic connectivity; and (iii) managing connectivity for riverine fishes. Challenges include the spatial structure of stream networks, the force and direction of flow, scale‐dependence of connectivity, shifting boundaries, complexity of behaviour and life histories and quantifying anthropogenic influence on connectivity and aligning management goals. As we discuss each challenge, we summarize relevant approaches in the literature and provide additional suggestions for improving research and management of connectivity for riverine fishes.
3. Specifically, we suggest that rapid advances are possible in the following arenas: (i) incorporating network structure and river discharge into analyses; (ii) increasing explicit consideration of temporal complexity and fish behaviour in the scope of analyses; and (iii) parsing degrees of human and natural influences on connectivity and defining acceptable alterations. Multiscale analyses are most likely to identify dominant patterns of connections and disconnections, and the appropriate scale at which to focus conservation activities.
1. Freshwater conservation has received less attention than its terrestrial or marine counterparts. Given the accelerated rate of change and intensive human use that freshwater ecosystems are submitted to, it is urgent to focus more attention on fresh waters. Existing conservation planning tools – such as Marxan – need to be modified to account for the special nature of these systems. Connectivity plays a key role in freshwater ecosystems. Threats are mediated along river corridors, and the condition of the entire catchment influences river biodiversity downstream. This needs to be considered in conservation planning.
2. The probabilities of occurrence of nine native freshwater fish species in a Mediterranean river basin, obtained from Multivariate Adaptive Regression Splines‐ Generalized Linear Model (MARS‐GLM) models, were used as features to develop spatial conservation priorities. The priorities accounted for complementarity and spatial design issues.
3. To deal with the connected nature of rivers, we modified Marxan’s boundary length penalty, avoiding the selection of isolated planning units and forcing the inclusion of closer upstream areas. We introduced ‘virtual boundaries’ between non‐headwater stream segments and added distance‐weighted penalties to the overall connectivity cost (CP) when stream segments upstream of the selected planning units are not selected.
4. This approach to prioritising connectivity is concordant with ecological theory, as it considers the natural and roughly exponential decay of upstream influences with distance. It accounts for the natural capacity of rivers to mitigate impacts when designing reserves. When connectivity was not emphasised, Marxan prioritised natural corridors for longitudinal movements. In contrast, whole sub‐basins were prioritised when connectivity was emphasised. Changing the relative emphasis on connectivity substantially changed the spatial prioritisation; our conservation investment could move from one basin to another.
5. Our novel approach to dealing with directional connectivity enables managers of freshwater systems to set ecologically meaningful spatial conservation priorities.
This paper establishes a framework within which a rapid and pragmatic assessment of river ecosystems can be undertaken at a broad, subcontinental scale, highlighting some implications for achieving conservation of river biodiversity in water-limited countries. The status of river ecosystems associated with main rivers in South Africa was assessed based on the extent to which each ecosystem had been altered from its natural condition. This requires consistent data on river integrity for the entire country, which was only available for main rivers; tributaries were thus excluded from the analyses. The state of main river ecosystems in South Africa is dire: 84% of the ecosystems are threatened, with a disturbing 54% critically endangered, 18% endangered, and 12% vulnerable. Protection levels were measured as the proportion of conservation target achieved within protected areas, where the conservation target was set as 20% of the total length of each river ecosystem. Sixteen of the 112 main river ecosystems are moderately to well represented within protected areas; the majority of the ecosystems have very low levels of representation, or are not represented at all within protected areas. Only 50% of rivers within protected areas are intact, but this is a higher proportion compared to rivers outside (28%), providing some of the first quantitative data on the positive role protected areas can play in conserving river ecosystems. This is also the first assessment of river ecosystems in South Africa to apply a similar approach to parallel assessments of terrestrial, marine, and estuarine ecosystems, and it revealed that main river ecosystems are in a critical state, far worse than terrestrial ecosystems. Ecosystem status is likely to differ with the inclusion of tributaries, since options may well exist for conserving critically endangered ecosystems in intact tributaries, which are generally less regulated than main rivers. This study highlights the importance of healthy tributaries for achieving river conservation targets, and the need for managing main rivers as conduits across the landscape to support ecological processes that depend on connectivity. We also highlight the need for a paradigm shift in the way protected areas are designated, as well as the need for integrated river basin management plans to include explicit conservation visions, targets, and strategies to ensure the conservation of freshwater ecosystems and the services they provide.
Prediction of species’ distributions is central to diverse applications in ecology, evolution and conservation science. There is increasing electronic access to vast sets of occurrence records in museums and herbaria, yet little effective guidance on how best to use this information in the context of numerous approaches for modelling distributions. To meet this need, we compared 16 modelling methods over 226 species from 6 regions of the world, creating the most comprehensive set of model comparisons to date. We used presence-only data to fit models, and independent presence-absence data to evaluate the predictions. Along with well-established modelling methods such as generalised additive models and GARP and BIOCLIM, we explored methods that either have been developed recently or have rarely been applied to modelling species’ distributions. These include machine-learning methods and community models, both of which have features that may make them particularly well suited to noisy or sparse information, as is typical of species’ occurrence data. Presence-only data were effective for modelling species’ distributions for many species and regions. The novel methods consistently outperformed more established methods. The results of our analysis are promising for the use of data from museums and herbaria, especially as methods suited to the noise inherent in such data improve.
Conservation plans are usually developed for regions that encompass only one environmental realm (terrestrial, freshwater or marine) because of logistical, institutional and political constraints. This is inadequate because these realms often interact through processes that form, utilize and maintain interfaces or connections, which are essential for the persistence of some species and ecosystem functions. We present a conceptual framework for systematic conservation prioritization that explicitly accounts for the connectivity between the terrestrial, marine, and freshwater realms. We propose a classification of this connectivity that encompasses: (1) narrow interfaces, such as riparian strips; (2) broad interfaces, such as estuaries; (3) constrained connections, such as corridors of native vegetation used by amphibians to move between natal ponds and adult habitat; and (4) diffuse connections, such as the movements of animals between breeding and feeding habitats. We use this taxonomy of inter-realm connectivity to describe existing and new spatial conservation prioritization techniques that aim to promote the persistence of processes that operate between realms.
In this chapter we ask the question: To what extent does an understanding of landscape spatial heterogeneity inform conservation decisions? We answer this question in the context of two central decision-making fields within conservation biology: systematic conservation planning and population viability analysis.The conservation planning principles of comprehensiveness and representativeness are fundamentally reliant on data and concepts of compositional landscape heterogeneity. The principle of adequacy is not accommodated in conservation planning very well and it relies on an understanding of the configurational heterogeneity of the landscape. A major challenge for conservation planning scientists is to develop theory and decision support tools that incorporate ideas of population viability and spatially explicit ecological processes. Population viability analysis invariably includes spatial population processes, and as a field has largely focused on the importance of the configurational heterogeneity of landscapes. We argue that this focus might only be justified when the scale of planning coincides with either the scale of habitat heterogeneity or the scale at which small populations operate. Integrating population viability analysis into conservation planning, and showing a balanced interest in compositional and configurational heterogeneity, are important future challenges.
Inter-wetland connectivity, defined here as the movement of biota among discrete water bodies, can have important population- and community-level consequences in aquatic systems. We examined inter-wetland connectivity in a southeastern Australian national park by intensively monitoring the movements of freshwater turtles (Chelodina longicollis) via capture-mark-recapture over a three-year period, and more sporadically for 25 years. A high percentage (33%) of turtles moved between wetlands, suggesting that single wetlands should not represent the minimum habitat unit harboring a C. longicollis population. Distance was the only structural landscape metric correlated with inter-patch transition probability, with probability declining as inter-wetland distance increased. Movements also appear to be strongly influenced by shifting resource quality gradients between temporary wetlands and permanent lakes according to drought and flood cycles, a pattern more consistent with migration between critical resource patches than occasional interpopulational dispersal. Rare dispersal events of up to 5.2 km were known to occur. Captures at a terrestrial drift fence suggest that small and immature turtles moved between wetlands more frequently than our aquatic sampling indicated. We caution that measures of actual (or functional) connectivity can be biased by sampling methods and the temporal scale of sampling and must also be interpreted in the context of factors that motivate animal movements. This requires some understanding of spatial and temporal variation in intra-patch processes (e.g., quality and extent) and the expected movement responses of animals (e.g., habitat selection) over extended time frames, information that can potentially yield more important insight on connectivity than measures of landscape structural features alone.
Habitat loss and deterioration, climate change, and economic pressures for resource extraction have all led to a global loss of biodiversity. The limited resources available for conservation need to be used both effectively and efficiently in order to minimise further losses. Spatial conservation prioritization addresses the question of how we should allocate conservation effort and funds in space and time. While the benefits of quantitative conservation prioritization methods have been widely promoted, adoption of these methods in "real-world" planning and implementation is still in its infancy, partly due to the difficulty of identifying which methods and tools (if any) are suited to specific planning problems. Spatial Conservation Prioritization brings together a team of leading scientists to introduce the conceptual and methodological aspects of how to undertake spatial conservation planning in a quantitative manner. It provides the reader with information on when, why, and how to use which statistical and computational methods for conservation prioritization. Important topics underlying spatial prioritization including metapopulation modelling, population viability analysis modelling, species distribution modelling, and uncertainty analysis are discussed, as well as operational definitions and methods. The book includes chapters on the most widely used and latest software, and concludes with an insight into the future of the field.
The dynamic and hierarchical nature of lotic ecosystems may be conceptualized in a four-dimensional framework. Upstream-downstream interactions constitute the longitudinal dimension. The lateral dimension includes interactions between the channel and riparian/floodplain systems. Significant interactions also occur between the channel and contiguous groundwater, the vertical dimension. The fourth dimension, time, provides the temporal scale. Lotic ecosystems have developed in response to dynamic patterns and processes occurring along these four dimensions. An holistic approach that employs a spatio-temporal framework, and that perceives disturbances as forces disrupting major interactive pathways, should lead to a more complete understanding of the dynamic and hierarchical structure of natural and altered lotic ecosystems.
Abstract Real patterns of ecological connectivity are seldom explicitly or systematically accounted for systematic conservation planning, in part because commonly used decision support systems can only capture simplistic notions of connectivity. Conventionally, the surrogates used to represent connectivity in conservation plans have assumed the connection between two sites to be symmetric in strength. In reality, ecological linkages between sites are rarely symmetric and often strongly asymmetric. Here, we develop a novel formulation that enabled us to incorporate asymmetric connectivity into the conservation decision support system Marxan. We illustrate this approach using hypothetical examples of a river catchment and a group of reefs, and then apply it to case studies in the Snowy River catchment and Great Barrier Reef, Australia. We show that incorporating asymmetric ecological connectivity in systematic reserve design leads to solutions that more effectively capture connectivity patterns, relative to either ignoring connectivity or assuming symmetric connectivity.
Contemporary river ecology is based primarily on biogeochemical studies of the river channel and interactions with shoreline vegetation, even though most rivers have extensive floodplain aquifers that are hydraulically connected to the channel. The hyporheic zone, the interstitial habitat penetrated by riverine animals, is characterized as being spatially limited to no more than a few metres, in most cases centimetres, away from the river channel1–9. However, riverine invertebrates were collected in hundreds per sample within a grid of shallow (10 m) wells located on the flood-plain up to 2 km from the channel of the Flathead River, Montana, USA. Preliminary mass transport calculations indicate that nutrients discharged from the hyporheic zone may be crucial to biotic productivity in the river channel. The strength and spatial magnitude of these interactions demonstrate an unexplored dimension in the ecology of gravel-bed rivers.
1. Planning for the conservation of river biodiversity must involve a wide range of management options and account for the complication that the effects of many actions are spatially removed from these actions. Reserve design algorithms widely used in conservation planning today are not well equipped to address such complexities.
2. We used process-based models to estimate the expected persistence of river biodiversity under alternative catchment-wide management scenarios and applied it in the Hunter Region (37 000 km²) in southeastern Australia.
3. The biological condition of 12 197 subcatchments was estimated using a multiple linear regression model that related assessments of the integrity of macroinvertebrate assemblages to human-induced disturbances at river sites. The best-fit model (R2 = 0.76) used measures of both local and catchment-wide disturbances as well as elevation and distance from source as predictor variables. Based on the outputs of this model, we estimated that substantial loss of river biodiversity had occurred in some parts of the coastal fringes and the lower parts of the larger river systems. The most affected river type was small, low-gradient streams.
4. The predicted biodiversity condition together with river types based on macroinvertebrate assemblages and abiotic attributes was used to estimate a biodiversity persistence index (BDI).
5. A priority value for each subcatchment was calculated for different actions by changing the disturbance values for that subcatchment and calculating the resulting marginal change in regional BDI. Maps were thereby created for three different types of priority: catchment protection priority, catchment restoration priority and river section conservation priority.
6. The subcatchments of high catchment protection priority for river biodiversity were mostly in the uplands and within protected areas. The river sections of high conservation priority included many coastal lowland rivers in and around protected areas as well as many upland headwater streams. Subcatchments of high priority for catchment restoration were mostly in coastal areas or lowland floodplains.
7. This approach may be particularly well suited to guide the integrated implementation of three place-based protection strategies proposed for freshwaters: focal areas, critical management zones and catchment management zones.
1. We review recent advances in systematic conservation planning in fresh waters. Most modern systematic planning approaches are based on the CARE principles: comprehensiveness, adequacy, representativeness and efficiency. Efficiency is usually provided by a complementarity-based strategy, aiming to select new conservation areas in the light of previously protected features. These strategies have to be modified to account for the connected nature of rivers.
2. Choice of surrogates for conservation features depends on the scale of the assessment, as well as the available expertise and resources. Ideally, real information about taxa or processes – extrapolated by models – ensures that target features are protected. Where this is not feasible, it is critical that the choice of environmental surrogates is informed by target biota or processes.
3. Setting adequacy targets – the most challenging aspect in planning – needs to be evaluated in a freshwater-specific context, as species–area relationships and the distribution of diversity differ in dendritic networks. Adequately designed conservation plans also need to consider upstream land use and catchment disturbances. Recent studies have largely addressed longitudinal connectivity either by setting rules to protect adjacent subcatchments (or even the entire catchment upstream), or by considering the magnitude of disturbance upstream of selected planning units. Very few studies have addressed lateral and vertical connectivity in a systematic way.
4. To implement freshwater conservation plans, we recommend adopting a recently proposed hierarchical protection strategy, from ‘freshwater focal areas’ that contain the actual features to be protected to mixed-use ‘catchment management zones’. Stakeholder involvement is crucial, especially in the large multi-use areas upstream and in the surrounding catchment.
5. We conclude that conservation planning using CARE principles is the only efficient way forward. This special issue shows significant efforts are under way to adapt freshwater-specific adequacy, connectivity and implementation issues in conservation planning. However, a more holistic research investment is required to link freshwater, terrestrial and marine ecosystems.
1. Global freshwater biodiversity is facing rapid decline. Freshwater conservation planning aims to reduce this decline by efficiently prioritising conservation actions.
2. This Special Issue presents nine papers from five continents demonstrating a wide range of approaches to spatial prioritisation for freshwater conservation and two papers that explore directions for research and implementation in conservation planning.
3. Despite an emphasis on running waters and data‐rich regions, these papers collectively offer a wide range of perspectives for advancing the science and practice of systematic conservation planning across freshwater realms, including data‐poor regions and standing‐water ecosystems.
1. Colonisation and population recovery are crucial to species persistence in environmentally variable ecosystems, but are poorly understood processes. After documenting movement rates for several species of stream fish, we predicted that this variable would influence colonisation rates more strongly than local abundance, per cent occupancy, body size and taxonomic family. We also predicted that populations of species with higher movement rates would recover more rapidly than species with lower movement rates and that assemblage structure would change accordingly.
2. To test these predictions, we removed fishes from a headwater and a mainstem creek in southwest Virginia and monitored colonisation over a 2‐year period. Using an information–theoretic approach, we evaluated the relative plausibility of 15 alternative models containing different combinations of our predictor variables. Our best‐supported model contained movement rate and abundance and was 41 times more likely to account for observed patterns in colonisation rates than the next‐best model. Movement rate and abundance were both positively related to colonisation rates and explained 88% of the variation in colonisation rates among species.
3. Population recovery, measured as the per cent of initial abundance restored, was also positively associated with movement rate. One species recovered within 3 months, most recovered within 2 years, but two species still had not recovered after 2 years. Despite high variation in recovery, the removal had only a slight impact on assemblage structure because species that were abundant in pre‐removal samples were also abundant in post‐removal samples.
4. The significance of interspecific variation in colonisation and recovery rates has been underappreciated because of the widely documented recovery of stream fish assemblages following fish kills and small‐scale experimental defaunations. Our results indicate that recovery of the overall assemblage does not imply recovery of each component species. Populations of species that are rare and less mobile will recover more slowly and will be more vulnerable to extinction in systems where chemical spills, hydrological alteration, extreme droughts and other impacts are frequent.
1. The progression of approaches in systematic conservation planning from representation to representation and persistence has greatly enhanced its potential applicability to freshwaters. However, conceptual frameworks that consolidate principles for incorporating persistence into freshwater conservation planning are still lacking.
2. We present four key principles to consider when planning for the persistence of freshwater biodiversity: selecting ecosystems of high ecological integrity; incorporating connectivity; incorporating areas important to population persistence; and identifying additional natural processes that can be mapped.
3. The practicalities of gathering data and conducting the conservation plan to address these principles are explored here using a case study in the Olifants/Doorn Water Management Area, South Africa. Spatial layers are developed for depicting ecological integrity, sub-catchment boundaries, riparian zones and wetlands, high water-yield areas and patterns of groundwater discharge and recharge.
4. These data are used to develop a conservation area network that supports both representation and persistence of freshwater biodiversity. Although the planning region is relatively data rich by global standards, several data deficiencies were identified. We suggest ways of using environmental surrogates to address data deficiencies, improving confidence in these surrogates by combining them wherever possible with existing field data and expert knowledge.
5. We also recommend methods to achieve spatial efficiency by simultaneously designing for representation and persistence of freshwater biodiversity. Spatial efficiency can be achieved in different ways when using a conservation planning algorithm and a multiple-use zoning strategy.
6. The allocation of multiple-use zones aligns closely with the objectives of integrated water resources management and land use planning. Given the practicalities at local levels of planning, we recommend using multiple-use zones in the design phase, rather than merely at the end once the design is complete.
Freshwater ecosystems and their associated biota are among the most endangered in the world. This, combined with escalating human pressure on water resources, demands that urgent measures be taken to conserve freshwater ecosystems and the services they provide. Systematic conservation planning provides a strategic and scientifically defensible framework for doing this.
Pioneered in the terrestrial realm, there has been some scepticism associated with the applicability of systematic approaches to freshwater conservation planning. Recent studies, however, indicate that it is possible to apply overarching systematic conservation planning goals to the freshwater realm although the specific methods for achieving these will differ, particularly in relation to the strong connectivity inherent to most freshwater systems.
Progress has been made in establishing surrogates that depict freshwater biodiversity and ecological integrity, developing complementarity‐based algorithms that incorporate directional connectivity, and designing freshwater conservation area networks that take cognizance of both connectivity and implementation practicalities.
Key research priorities include increased impetus on planning for non‐riverine freshwater systems; evaluating the effectiveness of freshwater biodiversity surrogates; establishing scientifically defensible conservation targets; developing complementarity‐based algorithms that simultaneously consider connectivity issues for both lentic and lotic water bodies; developing integrated conservation plans across freshwater, terrestrial and marine realms; incorporating uncertainty and dynamic threats into freshwater conservation planning; collection and collation of scale‐appropriate primary data; and building an evidence‐base to support improved implementation of freshwater conservation plans.
Copyright © 2008 John Wiley & Sons, Ltd.
Increasingly, biological reserves throughout the world are threatened by cumulative alterations in hydrologic connectivity within the greater landscape. Hydrologic connectivity is used here in an ecological sense to refer to water-mediated transfer of matter, energy, and/or organisms within or between elements of the hydrologic cycle. Obvious human influences that alter this property include dams, associated flow regulation, ground-water extraction, and water diversion, all of which can result in a cascade of events in both aquatic and terrestrial ecosystems. Even disturbances well outside the boundaries of reserves can have profound effects on the biological integrity of these ''protected'' areas. Factors such as nutrient and toxic pollution and the spread of nonnative species are perpetuated by hydrologic connectivity, and their effects can be exacerbated by changes in this property. Hydrological alterations are now affecting reserves through increasingly broad feedback loops, ranging from overdrawn aquifers to atmospheric deposition and global climate change. Such alterations are often beyond the direct control of managers because they lie outside reserve boundaries, and data on hydrologic connection between reserves and sur-rounding landscapes are scant. The subject of water has also been typically excluded from the literature pertaining to both theoretical and practical aspects of reserve size, isolation, and design. This results, in part, from early management strategies developed when the landscape matrix outside of reserves was not excessively fragmented, and when awareness of hydrologic connectivity was in its infancy. The location of a given reserve within a watershed, relative to regional aquifers and wind and precipitation patterns, can play a key role in its response to human disturbance transmitted through the hydrologic cycle. To illustrate this point, I discuss reserves of varying sizes from diverse regions throughout the world. Reserves located in middle and lower watersheds often suffer direct hydrologic alterations that cause severe habitat mod-ification and exacerbate the effects of pollution. In contrast, reserves in upper watersheds may have intact physical habitat and contain important source populations of some native biota, yet hydrologic disturbances in lower watersheds may cause extirpation of migratory species, cascading trophic effects, and genetic isolation. Worldwide, 7% of land area is either strictly or partially protected, and many reserves are in danger of becoming population ''sinks'' for wildlife if we do not develop a more predictive understanding of how they are affected by hydrologic alterations that originate outside of their boundaries.
1. Statistical modelling is often used to relate sparse biological survey data to remotely derived environmental predictors, thereby providing a basis for predictively mapping biodiversity across an entire region of interest. The most popular strategy for such modelling has been to model distributions of individual species one at a time. Spatial modelling of biodiversity at the community level may, however, confer significant benefits for applications involving very large numbers of species, particularly if many of these species are recorded infrequently.
2. Community-level modelling combines data from multiple species and produces information on spatial pattern in the distribution of biodiversity at a collective community level instead of, or in addition to, the level of individual species. Spatial outputs from community-level modelling include predictive mapping of community types (groups of locations with similar species composition), species groups (groups of species with similar distributions), axes or gradients of compositional variation, levels of compositional dissimilarity between pairs of locations, and various macro-ecological properties (e.g. species richness).
3. Three broad modelling strategies can be used to generate these outputs: (i) 'assemble first, predict later', in which biological survey data are first classified, ordinated or aggregated to produce community-level entities or attributes that are then modelled in relation to environmental predictors; (ii) 'predict first, assemble later', in which individual species are modelled one at a time as a function of environmental variables, to produce a stack of species distribution maps that is then subjected to classification, ordination or aggregation; and (iii) 'assemble and predict together', in which all species are modelled simultaneously, within a single integrated modelling process. These strategies each have particular strengths and weaknesses, depending on the intended purpose of modelling and the type, quality and quantity of data involved.
4. Synthesis and applications. The potential benefits of modelling large multispecies data sets using community-level, as opposed to species-level, approaches include faster processing, increased power to detect shared patterns of environmental response across rarely recorded species, and enhanced capacity to synthesize complex data into a form more readily interpretable by scientists and decision-makers. Community-level modelling therefore deserves to be considered more often, and more widely, as a potential alternative or supplement to modelling individual species.
This study has adapted a complementarity-based area-selection method to estimate conservation value/irreplaceability for river systems. Irreplaceability represents the likelihood that an area will be required as part of a conservation system that achieves all conservation targets. We adapt this measure – often used in marine or terrestrial planning – to consider whole-of-catchment protection in a riverine setting. After dividing the Australian state of Victoria into 1854 subcatchments, we successfully modelled distributions of 400 benthic macroinvertebrate taxa using generalized additive models. We calculated the minimum area required to protect all taxa using three different heuristic selection algorithms. The algorithms were modified to consider the entire upstream catchment for any subcatchment. A summed rarity algorithm, corrected for upstream area, proved to be the most efficient, requiring 100 000 hectares less total catchment area to represent all taxa than the second most efficient algorithm. We calculated irreplaceability by running the algorithm 1000 times and randomly removing 90% of the catchments in each run. From this analysis, we estimated two metrics: Fs (the frequency of selection) and average c (average contribution to conservation targets). Four groups of catchments were identified: (i) catchments that have high contributions and are always or very frequently selected; (ii) catchments that have high contributions and are infrequently selected; (iii) catchments that are always or very frequently selected but contribute few taxa; and (iv) catchments that are infrequently selected and contribute few taxa. Synthesis and applications. For the first time, a complementarity-based algorithm has been adapted to a riverine setting. This algorithm acknowledges the connected nature of rivers by considering not only the local assemblages, but also upstream areas that need to be protected. We demonstrated that using standard algorithms in these connected systems would lead to two mistakes, namely: (i) not all taxa would be covered by reserves that were buffered from potential human disturbances upstream; and (ii) the standard algorithms would not lead to the most efficient solution, potentially costing additional millions of dollars to any conservation scheme. We therefore recommend the use of our algorithm or a similar riverine adaptation of reserve design algorithms to ensure adequate and efficient conservation planning.
Current circumstances — that the majority of species distribution records exist as presence-only data (e.g. from museums and herbaria), and that there is an established need for predictions of species distributions — mean that scientists and conservation managers seek to develop robust methods for using these data. Such methods must, in particular, accommodate the difficulties caused by lack of reliable information about sites where species are absent. Here we test two approaches for overcoming these difficulties, analysing a range of data sets using the technique of multivariate adaptive regression splines (MARS). MARS is closely related to regression techniques such as generalized additive models (GAMs) that are commonly and successfully used in modelling species distributions, but has particular advantages in its analytical speed and the ease of transfer of analysis results to other computational environments such as a Geographic Information System. MARS also has the advantage that it can model multiple responses, meaning that it can combine information from a set of species to determine the dominant environmental drivers of variation in species composition. We use data from 226 species from six regions of the world, and demonstrate the use of MARS for distribution modelling using presence-only data. We test whether (1) the type of data used to represent absence or background and (2) the signal from multiple species affect predictive performance, by evaluating predictions at completely independent sites where genuine presence–absence data were recorded. Models developed with absences inferred from the total set of presence-only sites for a biological group, and using simultaneous analysis of multiple species to inform the choice of predictor variables, performed better than models in which species were analysed singly, or in which pseudo-absences were drawn randomly from the study area. The methods are fast, relatively simple to understand, and useful for situations where data are limited. A tutorial is included.
The current conservation crisis calls for research and management to be carried out on a long‐term, multi‐species basis at large spatial scales. Unfortunately, scientists, managers, and agencies often are stymied in their effort to conduct these large‐scale studies because of a lack of appropriate technology, methodology, and funding. This issue is of particular concern in wetland conservation, for which the standard landscape approach may include consideration of a large tract of land but fail to incorporate the suite of wetland sites frequently used by highly mobile organisms such as waterbirds (e.g., shorebirds, wading birds, waterfowl). Typically, these species have population dynamics that require use of multiple wetlands, but this aspect of their life history has often been ignored in planning for their conservation. We outline theoretical, empirical, modeling, and planning problems associated with this issue and suggest solutions to some current obstacles. These solutions represent a tradeoff between typical in‐depth single‐species studies and more generic multi‐species studies. They include studying within‐ and among‐season movements of waterbirds on a spatial scale appropriate to both widely dispersing and more stationary species; multi‐species censuses at multiple sites; further development and use of technology such as satellite transmitters and population‐specific molecular markers; development of spatially explicit population models that consider within‐season movements of waterbirds; and recognition from funding agencies that landscape‐level issues cannot adequately be addressed without support for these types of studies.
Movimientos de Aves y Conectividad de Humedales en la Conservación del Paisaje
La actual crísis en la conservación exige de investigación y manejo a desarrollarse en escalas de largo plazo, basada en multiples especies y en espacios grandes. Desafortunadamente, los científicos, manejadores y las agencias frecuentemente ven frustrados sus esfuerzos para conducir estos estudios de gran escala debido a la carencia de tecnología, metodologia y soporte económico apropiados. Este tema es de particular interés en la conservación de humedales donde la perspectiva común de paisaje pudiera considerar un área extensa de tierra pero no incorpora humedales aptos que son frecuentemente usados por organismos con alta movilidad como lo son las aves acuáticas (aves playeras o de vados, ganzos, patos). Tipicamente estas especies tienen dinámicas poblacionales que requiren del uso de multiples humedales, sin embargo, este aspecto de su historia de vida frecuentemente es ignorado en la planeación de su conservación. Resaltamos problemas teóricos, empíricos, de modelado y de planeación asociados con este tema y sugerimos soluciones para algunos obstáculos actuales. Estas soluciones representan un intercambio entre estudios a profundidad de una sola especie y estudios genéricos multiespecie. Estos últimos incluyen el estudio de movimientos de las aves acuáticas entre y dentro estaciones en una escala espacial apropriada tanto para aves de amplia dispersión y especies mas estacionarias; censos en múltiples sitios; desarrollo y uso de tecnología como los transmisores vía satélite y marcadores moleculares específicos de poblaciones; desarrollo de modelos poblacionales espacialmente explícitos que consideren movimientos de las aves acuáticas durante las estaciones y el reconocimiento de las agencias patrocinadoras de que asuntos a nivel de paisaje no podrán ser adecuadamente afrontados sin el apoyo para este tipo de estudios.
1. Systematic conservation planning is a process widely used in terrestrial and marine environments. A principal goal is to establish a network of protected areas representing the full variety of species or ecosystems. We suggest considering three key attributes of a catchment when planning for aquatic conservation: irreplaceability, condition and vulnerability.
2. Based on observed and modelled distributions of 367 invertebrates in the Australian state of Victoria, conservation value was measured by calculating an irreplaceability coefficient for 1854 subcatchments. Irreplaceability indicates the likelihood of any subcatchment being needed to achieve conservation targets. We estimated it with a bootstrapped heuristic reserve design algorithm, which included upstream–downstream connectivity rules. The selection metric within the algorithm was total summed rarity, corrected for protected area.
3. Condition was estimated using a stressor gradient approach in which two classes of geographical information system Layers were summarised using principal components analysis. The first class was disturbance measures such as nutrient and sediment budgets, salinisation and weed cover. The second class was land use layers, including classes of forestry, agricultural and urban use. The main gradient, explaining 56% of the variation, could be characterised as agricultural disturbance. Seventy-five per cent of the study area was classified as disturbed.
4. Our definition of vulnerability was the likelihood of a catchment being exposed to a land use that degrades its condition. This was estimated by comparing land capability and current land use. If land was capable of supporting a land use that would have a more degrading effect on a river than its current tenure, it was classified vulnerable (66% of the study area). 79% of catchments contained more then 50% vulnerable land.
5. When integrating the three measures, two major groups of catchments requiring urgent conservation measures were identified. Seven per cent of catchments were highly irreplaceable, highly vulnerable but in degraded condition. These catchments were flagged for restoration. While most highly irreplaceable catchments in good condition were already protected, 2.5% of catchments in this category are on vulnerable land. These are priority areas for assigning river reserves.
Freshwater species and habitats are among the most threatened In the world. One way in which this growing conservation concern can be addressed is the creation of freshwater protected areas. Here, we present three strategies for fresh water protected-area design and management: whole-catchment management, natural-flow maintenance, and exclusion of non-native species, These strategies are based on the three primary threats to fresh waters: land-use disturbances, altered hydrologies, and Introduction of non-native species. Each strategy draws from research in limnology and river and wetland ecology. Ideally, freshwater protected areas should be located in intact catchments, should have natural hydrological regimes, and should contain no non-native species. Because optimal conservation conditions are often difficult to attain, we also suggest alternative management strategies, including multiple-use modules, use of the river continuum concept, vegetated buffer strips partial water discharges, and eradication of exotic species. Under some circumstances it may be possible to focus freshwater conservation efforts on two key zones: adjacent terrestrial areas and headwaters.
1. Freshwater ecosystems are amongst the most threatened and poorly protected globally. They continue to be degraded through habitat loss, pollution and invading species and conservation measures are urgently needed to halt declining trends in their biodiversity and integrity.
2. During the past decade a suite of decision support tools and computational approaches have been developed for efficient and targeted conservation action in terrestrial or marine ecosystems. These methods may be poorly suited for planning in freshwater systems because connectivity in terrestrial and marine systems is typically modelled in a way unsuitable for rivers, where connectivity has a strong directional component.
3. We modify the conservation prioritization method and software, zonation , to account for connectivity in a manner better suited to freshwater ecosystems. Prioritization was performed using subcatchment/catchment‐based planning units and connectivity was modified to have directional upstream and downstream components consistent with the ecology of our target species.
4. We demonstrate this modified method for rivers and streams in the southern North Island of New Zealand. Data included predicted occupancy from boosted regression tree models of species distributions for 18 fish species. The study area covered 2.1 million hectares and included 394 first‐ to fourth order catchment or subcatchment planning units.
5. Realistic modelling of connectivity had a major influence on the areas proposed for conservation. If connectivity was ignored, recommended conservation areas were very fragmented. By contrast, when connectivity was modelled, high priority conservation targets consisted of entire river basins or headwater subcatchments.
6. The proposed method serves as a starting point for the implementation of reserve selection methods in river ecosystems.
Predicting the distribution of endangered species from habitat data is frequently perceived to be a useful technique. Models that predict the presence or absence of a species are normally judged by the number of prediction errors. These may be of two types: false positives and false negatives. Many of the prediction errors can be traced to ecological processes such as unsaturated habitat and species interactions. Consequently, if prediction errors are not placed in an ecological context the results of the model may be misleading. The simplest, and most widely used, measure of prediction accuracy is the number of correctly classified cases. There are other measures of prediction success that may be more appropriate. Strategies for assessing the causes and costs of these errors are discussed. A range of techniques for measuring error in presence/absence models, including some that are seldom used by ecologists (e.g. ROC plots and cost matrices), are described. A new approach to estimating prediction error, which is based on the spatial characteristics of the errors, is proposed. Thirteen recommendations are made to enable the objective selection of an error assessment technique for ecological presence/absence models.
1. Relationships between probabilities of occurrence for fifteen diadromous fish species and environmental variables characterising their habitat in fluvial waters were explored using an extensive collection of distributional data from New Zealand rivers and streams. Environmental predictors were chosen for their likely functional relevance, and included variables describing conditions in the stream segment where sampling occurred, downstream factors affecting the ability of fish to move upriver from the sea, and upstream, catchment‐scale factors mostly affecting variation in river flows.
2. Analyses were performed using multivariate adaptive regression splines (MARS), a technique that uses piece‐wise linear segments to describe non‐linear relationships between species and environmental variables. All species were analysed using an option that allows simultaneous analysis of community data to identify the combination of environmental variables best able to predict the occurrence of the component species. Model discrimination was assessed for each species using the area under the receiver operating characteristic curve (ROC) statistic, calculated using a bootstrap procedure that estimates performance when predictions are made to independent data.
3. Environmental predictors having the strongest overall relationships with probabilities of occurrence included distance from the sea, stream size, summer temperature, and catchment‐scale drivers of variation in stream flow. Many species were also sensitive to variation in either the average and/or maximum downstream slope, and riparian shade was an important predictor for some species.
4. Analysis results were imported into a Geographic Information System where they were combined with extensive environmental data, allowing spatially explicit predictions of probabilities of occurrence by species to be made for New Zealand's entire river network. This information will provide a valuable context for future conservation management in New Zealand's rivers and streams.
Declining trends in the integrity of freshwater systems demand exploration of all possible conservation solutions. Freshwater protected areas have received little attention, despite the prominence of protected areas as conservation interventions for terrestrial and more recently marine features. We argue that a dialogue on freshwater protected areas has been neglected both because few models of good protected area design exist, and because traditional notions of protected areas translate imperfectly to the freshwater realm. Partly as a result of this conceptual disconnect, freshwaters have been largely ignored in protected area accounting schemes, even though a number of existing freshwater conservation strategies could qualify according to general protected area definitions. Rather than impose terrestrially-motivated ideas about protected areas onto freshwaters, we propose new vocabulary – freshwater focal area, critical management zone, and catchment management zone – that can be used in conjunction with IUCN protected area categories and that recognize the special ecological dynamics of freshwaters, and in particular the critical role of fluvial processes. These terms, which attempt to diffuse concerns about locking away essential ecosystem goods and services, move us toward consideration of protected areas for freshwaters. This conceptual shift, which acknowledges that freshwater conservation may occur remotely from freshwater features, opens the door for improved integration of freshwater, terrestrial, and marine concerns in protected area design and management.
A method for assessing anthropogenic river disturbance is described. The grid-based spatial modeling procedure computes indices of disturbance for individual stream sections. These indices rank streams along a continuum from near-pristine to severely disturbed. The method couples geographical data, recording the extent and intensity of human activities known to impact on river condition, with a Digital Elevation Model (DEM) used for drainage analysis. It was developed to produce the first nation-wide assessment of river disturbance from which Australia’s least disturbed or ‘wild’ rivers were identified. A national summary of the extent and the potential impact of human activities is presented, calculated from the disturbance index values computed for more than 1.5×106 stream sections with a total length of over 3×106 km. Index values close to the undisturbed end of the continuum are rare, especially among large rivers. Most of the least disturbed streams are predicted to lie within the monsoonal tropical north or the arid/semi-arid center of the continent.The disturbance indices generated provide a comprehensive and consistent characterization of river and catchment disturbance that has applications beyond the identification of wild rivers. These include identification of priorities for rehabilitation and restoration; development of systematic survey strategies for aquatic, riparian and estuarine biota and identification of reserve networks for river systems. However, these applications depend on validating the correlation between river disturbance indices and intensively sampled physical and biological indicators of river condition.
Modelling techniques used in binary classification problems often result in a predicted probability surface, which is then translated into a presence–absence classification map. However, this translation requires a (possibly subjective) choice of threshold above which the variable of interest is predicted to be present. The selection of this threshold value can have dramatic effects on model accuracy as well as the predicted prevalence for the variable (the overall proportion of locations where the variable is predicted to be present). The traditional default is to simply use a threshold of 0.5 as the cut-off, but this does not necessarily preserve the observed prevalence or result in the highest prediction accuracy, especially for data sets with very high or very low observed prevalence. Alternatively, the thresholds can be chosen to optimize map accuracy, as judged by various criteria. Here we examine the effect of 11 of these potential criteria on predicted prevalence, prediction accuracy, and the resulting map output. Comparisons are made using output from presence–absence models developed for 13 tree species in the northern mountains of Utah. We found that species with poor model quality or low prevalence were most sensitive to the choice of threshold. For these species, a 0.5 cut-off was unreliable, sometimes resulting in substantially lower kappa and underestimated prevalence, with possible detrimental effects on a management decision. If a management objective requires a map to portray unbiased estimates of species prevalence, then the best results were obtained from thresholds deliberately chosen so that the predicted prevalence equaled the observed prevalence, followed closely by thresholds chosen to maximize kappa. These were also the two criteria with the highest mean kappa from our independent test data. For particular management applications the special cases of user specified required accuracy may be most appropriate. Ultimately, maps will typically have multiple and somewhat conflicting management applications. Therefore, providing users with a continuous probability surface may be the most versatile and powerful method, allowing threshold choice to be matched with each maps intended use.
1. Previous attempts to identify nationally important wetlands for biodiversity in New Zealand were based on expert panel opinions because quantitative approaches were hampered by a lack of data. We apply principles of systematic conservation planning to remote sensing data within a geographical information system (GIS) to identify nationally important palustrine and inland saline wetlands.
2. A catchment-based classification was used to divide New Zealand into 29 biogeographic units. To meet representation goals, all wetland classes need to be protected within each unit.
3. We mapped current and historic wetlands down to a minimum size of 0.5 ha. Over 7000 current wetlands were mapped using standardised satellite imagery and a collection of point or polygon data. Historical extent was estimated from soil information refined using a digital elevation model. The current extent of wetlands is 10% of the historic extent, which is consistent with previous estimates.
4. A classification was produced using fuzzy expert rules within a GIS to identify seven wetland classes: bog, fen, swamp, marsh, pakihi/gumland, seepage and inland saline. Swamps and pakihi/gumland are the most common, but the former has sustained the greatest reduction in area with only 6% of its historical extent remaining. A preliminary field assessment of classification accuracy in the Otago region found only 60% agreement, mainly because of the misclassification of marshes into swamps.
5. Wetland condition was estimated using six measures of human disturbance (natural cover, human-made impervious cover, introduced fish, woody weeds, artificial drainage and nitrate leaching risk) applied at three spatial scales: the wetland’s catchment, a 30-m buffer around the wetland and the wetland itself. Measures were transformed and combined into a single condition index. More than 60% of remaining wetlands had condition indices <0.5, probably indicating moderate to severe degradation and loss of native biodiversity.
6. Sites were ranked within each biogeographic unit using the wetland classification to ensure a representative set of wetland diversity. Rankings were determined by combining condition and complementarity to calculate conservation effectiveness that was then weighted by irreplaceability. Highest ranked sites in each biogeographic unit were usually the largest remaining wetlands that contained multiple wetland classes. This reflects their potential to protect a diverse range of wetland classes and a high proportion of the remaining habitat.
Aim To identify key research questions and challenges that will, if addressed in a timely manner, significantly advance the field of freshwater fish biogeography and conservation.
Location Globe.
Methods By drawing on expertise from different regions of the world, we integrate an illustrative conspectus of recent scientific advancements in fish biogeography with a prospectus of needed areas of scientific inquiry to identify information gaps and priority research needs to advance the science.
Results We identified the following core challenges: (1) Testing current and forging new theories in biogeography; (2) Advancing a trait‐based biogeography of freshwater fishes; (3) Quantifying extinction risk and loss of fish species in a changing environment; (4) Evaluating the magnitude and geography of extinction debt for freshwater fishes; (5) Elucidating the patterns and drivers of freshwater fish invasions; (6) Forecasting the future geography of freshwater fishes; (7) Understanding the interactive effects of multiple stressors in freshwater ecosystems; (8) Quantifying new features of the biodiversity crisis: fish faunal homogenization and the emergence of novel assemblages; (9) Promoting scientific rigour in emerging freshwater fish conservation strategies and (10) Improving conservation planning strategies for freshwater fish species.
Main conclusions By reflecting on recent scientific progress in fish conservation biogeography, we have identified a set of core challenges and priorities requiring future research investment.
We produced a conservation plan that achieved conservation targets for biodiversity pattern and process in the species- and endemic-rich Cape Floristic Region of South Africa. Features given quantitative conservation targets were land classes, localities of Proteaceae and selected vertebrate (freshwater fish, amphibians and reptiles) species, population sizes for medium- and large-sized mammals, and six types of spatial surrogates for ecological and evolutionary processes. The plan was developed in several stages using C-Plan, a decision support system linked to a geographic information system. Accepting the existing reserve system as part of the plan, we first selected spatially fixed surrogates for biodiversity processes; then we included those planning units that were essential for achieving targets for land classes, Proteaceae and vertebrate species; next we included areas required to accommodate population and design targets for large and medium-sized mammals; we then selected planning units required to conserve entire upland-lowland and macroclimatic gradients; and finally we resolved the options for achieving remaining targets while also consolidating the design of conservation areas. The result was a system of conservation areas, requiring, in addition to the existing reserve system, 52% of the remaining extant habitat in the planning domain, as well as restorable habitat, that will promote the persistence and continued diversification of much of the region's biota in the face of ongoing habitat loss and climate change. After describing the planning process, we discuss implementation priorities in relation to conservation value and vulnerability to habitat loss, as well as socio-economic, political and institutional. constraints and opportunities. (C) 2003 Elsevier Science Ltd. All rights reserved.
Loss of biodiversity is one of the world's overriding environmental challenges. Reducing those losses by creating reserve networks is a cornerstone of global conservation and resource management. Historically, assembly of reserve networks has been ad hoc, but recently the focus has shifted to identifying optimal reserve networks. We show that while comprehensive reserve network design is best when the entire network can be implemented immediately, when conservation investments must be staged over years, such solutions actually may be sub-optimal in the context of biodiversity loss and uncertainty. Simple decision rules, such as protecting the available site with the highest irreplaceability or with the highest species richness, may be more effective when implementation occurs over many years.
Systematic conservation planning research has focused on designing systems of conservation areas that efficiently protect a comprehensive and representative set of species and habitats. Recently, there has been an emphasis on improving the adequacy of conservation area design to promote the persistence and future generation of biodiversity. Few studies have explored incorporating ecological and evolutionary processes into conservation planning assessments. Biodiversity in Australia is maintained and generated by numerous ecological and evolutionary processes at various spatial and temporal scales. We accommodated ecological and evolutionary processes in four ways: (1) using sub-catchments as planning units to facilitate the protection of the integrity and function of ecosystem processes occurring on a sub-catchment scale; (2) targeting one type of ecological refugia, drought refugia, which are critical for the persistence of many species during widespread drought; (3) targeting one type of evolutionary refugia which are important for maintaining and generating unique biota during long-term climatic changes; and (4) preferentially grouping priority areas along vegetated waterways to account for the importance of connected waterways and associated riparian areas in maintaining processes. We identified drought refugia, areas of relatively high and regular herbage production in arid and semiarid Australia, from estimates of gross primary productivity derived from satellite data. In this paper, we combined the novel incorporation of these processes with a more traditional framework of efficiently representing a comprehensive sample of biodiversity to identify spatial priorities across Australia. We explored the trade-offs between economic costs, representation targets, and connectivity. Priority areas that considered ecological and evolutionary processes were more connected along vegetated waterways and were identified for a small increase in economic cost. Priority areas for conservation investment are more likely to have long-term benefits to biodiversity if ecological and evolutionary processes are considered in their identification.