Trophic Structure and Productivity of Silver Springs, Florida

Perspective: Flawed assumptions behind analysis of litter decomposition, steady state and fire risks in Australia

Article

Full-text available

Mar 2024
FOREST ECOL MANAG

Article

Jan 2020

Arnold van der Valk

Howard Thomas Odum (1924-2003) was an important transitional figure in the development of wetland ecology in the United States. Although he was educated before wetland ecology became a recognized subdiscipline of ecology, his research during the first half of his academic career (ca. 1950 to 1975) was focused primarily on wetlands. By the early 1970s, he was self-identifying as a wetland ecologist, e.g., by establishing the Center for Wetlands at the University of Florida. Although Odum was interested in much more than wetlands, especially during the last half of his lengthy career, he contributed significantly to increasing the visibility of wetlands and to the development of wetland ecology in four principal ways: (1) his innovative and influential research on the trophic structure of Silver Springs, a riverine wetland; (2) his highly visible research on the use of Cypress Domes to treat waste water; (3) his establishment of a major academic, wetland research institute, the Center for Wetlands; and (4) his many graduate students who obtained influential jobs in academia, government agencies and private companies. When Odum started his academic career wetland ecology did not exist. Halfway through it, wetland ecology began to arise as a distinct discipline and Odum was one of the major reason why this happened.

Spatial patterns of submerged macrophyte communities in select Florida spring-run streams: A review with new data

Article

Full-text available

Jul 2022

Florida springs and the spring-run streams they create (''springs'' for brevity) support extensive/dense communities of submerged aquatic vegetation (algae and macrophytes). Surveys of these communities in many springs using various methods have been conducted in the past, but no attempt has been made to conduct cross-system comparisons to elucidate spatial patterns in submerged aquatic vegetation among different springs. This study compared recent and prior submerged macrophyte community data from selected Florida springs and discussed spatial patterns observed. In particular, a distinct dichotomy was seen, with some spring macrophyte communities entirely dominated by Sagittaria kurziana and others by Vallisneria americana. In springs where both species occurred, Sagittaria was generally found to be the dominant plant in upstream reaches and Vallisneria was dominant or co-occurred with Sagittaria downstream. Comparison of data collected from prior field and mapping surveys of submerged vegetation conducted in these and other spring-run streams confirms these patterns. This dichotomy of ''Sagittaria springs'' versus ''Vallisneria springs'' prompts the question of what environmental drivers create these differences. A better understanding of this may help explain the shifts in vegetation that have been seen in spring-run streams over the past few decades.

Springs ecosystem classification

Article

Full-text available

Oct 2020
ECOL APPL

Springs ecosystems are globally abundant, geomorphologically diverse, and bio‐culturally productive, but are highly imperiled by anthropogenic activities. More than a century of scientific discussion about the wide array of ecohydrological factors influencing springs has been informative, but has yielded little agreement on their classification. This lack of agreement has contributed to the global neglect and degradation of springs ecosystems by the public, scientific, and management communities. Here we review the historical literature on springs classification variables, concluding that site‐specific source geomorphology remains the most diagnostic approach. We present a conceptual springs ecosystem model that clarifies the central role of geomorphology in springs ecosystem development, function, and typology. We present an illustrated dichotomous key to terrestrial (non‐marine) springs ecosystem types and subtypes, and describe those types. We identify representative reference sites, although data limitations presently preclude selection of continentally or globally representative reference springs of each type. We tested the classification key using data from 244 randomly selected springs of 13 types that were inventoried in western North America. The dichotomous key correctly identified springs type in 87.5% of the cases, with discrepancies primarily due to differentiation of primary vs. secondary typology, and insufficient inventory team training. Using that information, we identified sources of confusion and clarified the key. Among the types that required more detailed explanation were hypocrenes, springs in which groundwater is expressed through phreatophytic vegetation. Overall, springs biodiversity and ecosystem complexity are due, in part, to the co‐occurrence of multiple intra‐springs microhabitats. We describe microhabitats that are commonly associated with different springs types, reporting at least 13 microhabitats, each of which can support discrete biotic assemblages. Interdisciplinary agreement on basic classification is needed to enhance scientific understanding and stewardship of springs ecosystems, the loss and degradation of which constitute a global conservation crisis.

Ebullition of oxygen from seagrasses under supersaturated conditions

Article

Full-text available

Aug 2019

Gas ebullition from aquatic systems to the atmosphere represents a potentially important fraction of primary production that goes unquantified by measurements of dissolved gas concentrations. Although gas ebullition from photosynthetic surfaces has often been observed, it is rarely quantified. The resulting underestimation of photosynthetic activity may significantly bias the determination of ecosystem trophic status and estimated rates of biogeochemical cycling from in situ measures of dissolved oxygen. Here, we quantified gas ebullition rates in Zostera marina meadows in Virginia, U.S.A. using simple funnel traps and analyzed the oxygen concentration and isotopic composition of the captured gas. Maximum hourly rates of oxygen ebullition (3.0 mmol oxygen m −2 h −1) were observed during the coincidence of high irradiance and low tides, particularly in the afternoon when oxygen and temperature maxima occurred. The daily ebullition fluxes (up to 11 mmol oxygen m −2 d −1) were roughly equivalent to net primary production rates determined from dissolved oxygen measurements indicating that bubble ebullition can represent a major component of primary production that is not commonly included in ecosystem-scale estimates. Oxygen content comprised 20-40% of the captured bubble gas volume and correlated negatively with its δ 18 O values, consistent with a predominance of mixing between the higher δ 18 O of atmospheric oxygen in equilibrium with seawater and the lower δ 18 O of oxygen derived from photosynthesis. Thus, future studies interested in the metabolism of highly productive, shallow water ecosystems, and particularly those measuring in situ oxygen flux, should not ignore the bubble formation and ebullition processes described here.

Current Status and Conservation of Springs in Taiwan: Water Quality Assessment and Species Diversity of Aquatic Animals

Article

Full-text available

Feb 2023
Diversity

Even though spring ecosystems are ecologically unique and socio-culturally important worldwide, they hardly attract research attention. The aims of this study were to evaluate the environmental status of water quality, and to inventory the species diversity of aquatic animals in 65 springs in Taiwan from 2012 to 2017, of which seven springs were unable to be sampled due the fact that they were dried or sealed up. The environmental status of 58 springs with complete water quality data was assessed by the River Pollution Index (RPI). Based on the RPI, the water quality of these 58 sampled springs was mainly non-/mildly polluted (26 springs, 44.8%) and lightly polluted (23 spring, 39.6%), and nine (15.5%) springs were moderately polluted. However, when applied to springs, the RPI may intensify the pollution rankings because dissolved oxygen is an assessing factor, and hypoxia may naturally be observed in the springs. To avoid this concern, we suggest choosing the concentration of coliform instead of dissolved oxygen content in the RPI when it is applied to springs. During the 6 years of the study period, we collected 48 fish species in 44 springs, 24 gastropoda and bivalve species in 46 springs, 16 shrimp species in 34 springs, and 14 crab species in 18 springs. Within the species collected, 31 fish, 20 gastropoda and bivalves, 12 shrimps, and 14 crabs are native species of Taiwan. They totaled 27.2 to 35% of the known aquatic native species of the island. Thus, springs in Taiwan may be considered to be a conservation hotspot of aquatic animals. Other than native species, exotic aquatic animals also represent threats, as seventeen fishes (35.4%), four gastropoda and bivalves (16.6%), and two shrimps (12.5%) were found in the springs of Taiwan. The springs in Taiwan show diverse and vital ecosystem services, such as delivering social, cultural, and economic value, conserving native and endangered freshwater animals, developing new academic theories, and supplying habitat refugees from climate change. Unfortunately, springs in Taiwan currently are also threatened by multiple anthropogenic disturbances, such as the overconsumption of groundwater by land development and urbanization, deterioration of water quality by agricultural, domestic, and industrial pollution, and inappropriate tourism and management tactics. To restore and sustain the springs in Taiwan, effective strategies and practical measures are urgently required to minimize human-caused threats and revitalize social awareness of springs.

Life history responses of two co-occurring congeneric Apple Snails (Pomacea maculata and P. paludosa) to variation in water depth and metaphyton total phosphorus

Article

Full-text available

Jan 2023
HYDROBIOLOGIA

Hydrological and trophic gradients influence primary consumer populations in aquatic ecosystems, but their impacts remain unresolved for some species. We quantified the effects of water depth variation on reproduction and the effects of metaphyton (food) total phosphorus (TP) on juvenile growth and survival of two species of apple snails. The two species (native Pomacea paludosa and non-native P. maculata) are the exclusive prey of the federally endangered Snail Kite (Rostrhamus sociabilis) in Florida, USA. Using observations of reproduction in an ecotone habitat across four wetlands over three years, we statistically modeled seasonal reproductive dynamics. We found that P. paludosa reproduction peaked at depths of 30 cm during periods of cool temperatures (20°C; Feb-Apr), and P. maculata reproduction peaked at deeper depths (52 cm) and longer photoperiods (Jun-Jul). From in situ cage experiments in the same wetlands, we found that juvenile growth of both species increased with TP (129–403 µg g⁻¹), but non-native P. maculata responded more strongly than native P. paludosa. Survival of both species was high (> 97%) across all TP levels. In combination, the results were consistent with anecdotal distributional patterns across hydrologic and nutrient gradients and suggest a wider range of tolerance for the non-native P. maculata.

Impact of Pesticides on Invertebrates in Aquatic Ecosystem

Chapter

Full-text available

Jan 2020

Aquatic ecosystems do not contain more than a fragment of the global water resources, but they are exclusive and complex habitats due to the extremely close association between terrestrial and aquatic habitats. The important fish stocks and a unique set of organisms that provides priceless consumer services , such as chemical water purification and organic matter processing, are affected. The pollution of aquatic ecosystems with pesticides applied in agricultural production is widely acknowledged as one of the greatest anthropogenic stressors to stream ecosystems, and agricultural pesticides are known to cause a threat to all living organisms in stream ecosystems. The general objective of this chapter is to study the effects of agricultural pesticides on invertebrates. There are only a few evaluating effects of pesticide contamination resulting from normal agricultural practice on invertebrates, and there is a lack of studies focusing on the indirect effects of pesticides. The importance of physical habitat degradation in the assessment and mitigation of pesticide risk in agricultural streams will be discussed.

An in situ study of production from diel oxygen modelling, oxygen exchange, and electron transport rate in the kelp Ecklonia radiata

Article

Full-text available

Apr 2019

Macroalgal forests provide the foundation for most shallow reef ecosystems in temperate environments; hence tools for accurately measuring primary productivity are integral for ecosystem management. This study compares estimates of production/potential production in an Ecklonia radiata kelp forest in Tasmania, Australia, using diel oxygen gross primary production (GPP) models, benthic exchange chambers, and electron transport rate in photosystem II measured using PAM fluorometry. Two approaches to modelling GPP show good fit with environmental dissolved oxygen (DO), with gross oxygen production of the kelp bed ranging between ~0−20 for one model and ~0−8 µmol O 2 m ⁻² s ⁻¹ for the other, with total daily GPP (±SE) of 464 ± 28 and 347 ± 7 mmol O 2 m ⁻² , respectively. The oxygen production rate of E. radiata in benthic chambers ranged between 0 and 9.6 µmol O 2 m ⁻² s ⁻¹ , with total daily production as 204 ± 13 mmol O 2 m ⁻² , half that estimated from modelling DO. The peak value for maximum relative electron transport rate was 49 µmol e – m ⁻² s ⁻¹ at PAR of 208 µmol m –2 s ⁻¹ . Oxygen evolution from benthic chambers and electron transport rates from PAM fluorometry were well correlated; however, the latter may overestimate oxygen production. Water column DO can measure GPP of the benthic communities; however, additional measurements/more sophisticated models may be necessary. Benthic exchange chambers and PAM fluorometry can potentially estimate the contribution of E. radiata to total daily production provided that the measurements can be calibrated with other methods to obtain actual productivity. Additionally, upscaling requires reliable biomass estimates.

Seeds of Pistia stratiotes L. (water lettuce) in the paleo-sediments of Lake Annie, Florida

Article

Full-text available

Mar 2024
J PALEOLIMNOL

Pistia stratiotes L. (water lettuce) is a floating tropical macrophyte long identified and managed as a non-native species within the State of Florida and other areas of the southern United States. Macrofossil seeds from Lake Annie, Florida, however, indicate abundant presence of P. stratiotes intermixed with other locally native macrophytes from ~13,500 to ~12,000 calibrated years before present (cal yr BP). This was soon after the lake depression first began filling with water as the piezometric groundwater surface of the Florida peninsula rose in response to rising seas during the transition (~18,000 to ~11,000 cal yr BP) from the Last Glacial Maximum (LGM) to the Holocene interglacial. These macrofossil records join several other lines of evidence supporting native status of P. stratiotes in the Florida peninsula. While recent cryptic invasion of non-native Pistia genotypes into some of Florida’s freshwater ecosystems also appears likely, confirmed paleo-presence and contemporary persistence of native P. stratiotes subpopulations may have especially important management and conservation implications for Florida’s spring-fed streams. Palaeobotanical evidence of this type may be useful in further resolving the global biogeography of P. stratiotes and other cryptic aquatic plant species.

Indicators of salinization in spring-fed rivers using submerged aquatic vegetation

Article

Full-text available

Jan 2023

Madison Trowbridge

Monthly variation in organic-matter decomposition in agricultural stream and riparian ecosystems

Article

Full-text available

Jun 2023

Most field studies of organic-matter decomposition in streams have been conducted in highly seasonal temperate zones during the autumn; few, however, have examined decomposition during other seasons or evaluated within-season variability in decomposition rates. To address these gaps, we performed a cotton-strip decomposition assay and measured stream respiration monthly for one calendar year in three agricultural streams (and adjacent riparian zones) in Michigan (USA). Stream decomposition rates were highly variable among sampling months and were generally greatest during summer and lowest during winter. Variability in rates among sampling months (as a coefficient of variation) was greater in spring and autumn than in the summer and winter. Rates were higher in the most agricultural stream and lower in the stream from the watershed with the most forest cover; the agricultural stream with conservation efforts had rates that were intermediate. Principal component analysis revealed that higher stream decomposition rates were associated with elevated temperatures, turbidity, and soluble reactive phosphorus concentrations. Temporal and spatial trends were less pronounced in riparian zones, where decomposition rates were generally lower than in steams and were not correlated with stream decomposition rates. Microbial respiration rates measured on cotton strips were strongly correlated with strip decomposition rates. Reach-scale respiration rates followed a dual-peak temporal pattern, spiking in summer when stream temperatures were high and in the autumn when there was high organic-matter input. Taken together, these results highlight the broad variability in decomposition rates that can occur across a calendar year and the dynamic nature of ecosystem processes in agricultural streams.

Food webs coupled in space: Consumer foraging movement affects both stocks and fluxes

Article

Full-text available

Jun 2023
ECOLOGY

The exchange of material and individuals between neighboring food webs is ubiquitous and affects ecosystem functioning. Here, we explore animal foraging movement between adjacent, heterogeneous habitats and its effect on a suite of interconnected ecosystem functions. Combining dynamic food web models with nutrient‐recycling models, we study foraging across habitats that differ in fertility and plant diversity. We found that net foraging movement flowed from high to low fertility or high to low diversity and boosted stocks and flows across the whole loop of ecosystem functions, including biomass, detritus, and nutrients, in the recipient habitat. Contrary to common assumptions, however, the largest flows were often between the highest and intermediate fertility habitats rather than highest and lowest. The effect of consumer influx on ecosystem functions was similar to the effect of increasing fertility. Unlike fertility, however, consumer influx caused a shift toward highly predator‐dominated biomass distributions, especially in habitats that were unable to support predators in the absence of consumer foraging. This shift resulted from both direct and indirect effects propagated through the interconnected ecosystem functions. Only by considering both stocks and fluxes across the whole loop of ecosystem functions do we uncover the mechanisms driving our results. In conclusion, the outcome of animal foraging movements will differ from that of dispersal and diffusion. Together we show how considering active types of animal movement and the interconnectedness of ecosystem functions can aid our understanding of the patchy landscapes of the Anthropocene.

Cascading effects of elephant-human interactions and the role of space and mobility in sustaining biodiversity

Article

Full-text available

May 2023

Our study monitored the changes in elephant numbers, distribution, and ecological impacts over a 50-year period. During this period, the free-ranging intermingled movements of wildlife and traditional subsistence pastoralists across the Amboseli ecosystem were disrupted by a national park, livestock ranches, farms, settlements, and changing lifestyles and economies. Elephants compressed into the national park by poaching and settlement turned woodlands to grassland and shrublands, and swamps into short grazing lawns, causing a reduction of plant and herbivore diversity and resilience to extreme events. The results echo the ecological findings of high-density elephant populations in protected areas across eastern and southern Africa. The impact has led to the view of elephants in parks as being incompatible with biodiversity and to population control measures. In contrast to Amboseli National Park, we found woody vegetation grew and plant diversity fell in areas abandoned by elephants. We therefore used naturalistic and exclosure experiments to determine the density-dependent response of vegetation to elephants. We found plant richness to peak at the park boundary where elephants and livestock jostled spatially, setting up a creative browsing-grazing tension that caused a patchwork of habitats and peak of plant richness. Prehistorical and historical literature reviews lend support to the Amboseli findings that elephants and people, the two dominant keystone species in the savannas, have been intimately entangled and coexisted prior to the global ivory trade and colonialism. The findings point to the need to view specific elephant populations in historical perspective and, as far as possible , create connectivity beyond protected areas to allow mobility on an ecosystem and landscape scale. The Amboseli study underscores the significance of space and mobility in the keystone role of elephants, and community-based conservation as a way to foster coexistence at an ecosystem and landscape scale. Space and mobility also alleviate the ecological disruption of compressed populations, and minimizes population management. K E Y W O R D S biodiversity, compression-impact, elephants and humans, keystone role, mobility, space

Predicting ecological outcomes using fuzzy interaction webs

Article

Full-text available

May 2023
ECOLOGY

The past 100 years of empirical research in ecology have generated tremendous knowledge about the component interactions that structure ecological communities. Yet, we still lack the ability to reassemble these puzzle pieces to predict community responses to perturbations, a challenge that grows increasingly urgent given rapid global change. We summarize key advances in community ecology that have set the stage for modeling ecological systems and briefly review the evolution of ecological modeling efforts to identify critical hurdles to progress. We find that while Robert May demonstrated that quantitative models could theoretically predict community interactions nearly 50 years ago, in practice, we still lack the ability to predict ecological outcomes with reasonable accuracy for three reasons: (1) quantitative models require precise data for parameterization (often unavailable) and have restrictive assumptions that are rarely met; (2) estimating interaction strengths for all network components is extremely challenging; and (3) determining which species are essential to include in models is difficult (model structure uncertainty). We propose that fuzzy interaction webs (FIW), borrowed from the social sciences, hold the potential to overcome these modeling shortfalls by integrating quantitative and qualitative data (e.g., categorical data, natural history information, expert opinion) for generating reasonably accurate qualitative predictions sufficient for addressing many ecological questions. We outline recent advances developed for addressing model structure uncertainty, and we present a case study to illustrate how FIWs can be applied for estimating community interaction strengths and predicting complex ecological outcomes in a multitrophic (plants, herbivores, predators), multi‐interaction‐type (competition, predation, facilitation, omnivory) grassland ecosystem. We argue that incorporating FIWs into ecological modeling could significantly advance empirical and theoretical ecology.

Auckland Economy and its Interactions with the Environment: Insights from Input-Output Analysis

Book

Full-text available

Oct 2008

Humedales de ciudad: vivos, activos y resilientes

Book

Jul 2022

El vínculo entre el río Negro y los humedales del altiplano del Oriente Antioqueño es muy cercano y tiene miles de años de historia. Tiempo en el cual se han tejido delicados lazos entre las especies que los habitan, incluyéndonos. Muchas de estas relaciones y especies, a veces invisibles a nuestros ojos, se han podido dilucidar y socializar en los últimos años cuando se logra articular la academia con el Estado. Es de esta manera que el presente trabajo busca dar continuidad a la primera fase de esta iniciativa de delimitación y caracterización de estos ecosistemas estratégicos. Dos de las preguntas que se buscan responder en esta ocasión son: ¿Para qué sirven y cómo funcionan nuestros humedales?, la respuesta no es fácil, ni posible de abordar desde una sola área del saber. Es por esta razón que la información generada en este trabajo es el resultado de la sinergia de diversas áreas del conocimiento científico y social trabajando de manera transdisciplinar. Este valioso aporte abre las puertas a un trabajo mancomunado entre diferentes actores de la academia, la alcaldía de Rionegro y la Corporación Autónoma Regional de las cuencas de los ríos Negro y Nare (Cornare). A lo largo de los capítulos de este libro se abordará una temática que busca comprender diferentes dinámicas funcionales de estos ambientes, que van desde lo físico, organísmico, perceptual, educativo, económico, histórico y normativo. Esperamos que la información que aquí se presenta pueda generar nuevas preguntas, que nos permitan seguir profundizando en la dinámica funcional de estos ambientes con miras a su adecuada gestión, conservación y apropiación social.

Differential effects of increased salinity on growth and survival of a native and a nonnative apple snail species

Article

Jun 2022
J MOLLUS STUD

During the 21st century, wetlands are predicted to decrease by an estimated 70% worldwide due to multiple factors, including climate change (Nicholls, Hoozemans & Marchand, 1999; Fagherazzi et al., 2012). Saltwater intrusion linked to sea level rise and diverted river flow will have a significant impact on Florida's wetland ecosystems (Herbert et al., 2015). While the natural drivers of saltwater intrusion include storm surges, hurricanes and an oscillating climate, anthropogenic-driven changes in hydrology and climate change intensify the effects of rising sea levels (White & Kaplan, 2017). A projected global mean sea level rise of 8–16 mm/yr is predicted between 2081 and 2100, resulting in a 0.52–0.98 m rise by 2100 (IPCC, 2013). The rate of environmental change and a species’ sensitivity to change determine whether a species can adapt fast enough to survive a changing climate (Pearlstine, Pearlstine & Aumen, 2010). In Florida, due to drainage needs for agricultural and residential development, canals and levees were constructed, which over time have had a detrimental impact upon Florida's wetland ecosystems. Approximately 50% of the Everglades has been drained since Florida flood control projects were established in 1948 (Scheidt & Kalla, 2007), and the hydrology of the remaining wetlands has been altered (Gunderson, 1989). These changes have caused a decline in native apple snail populations, which are the predominant food source of the Florida snail kite (Rostrhamus sociabilis plumbeus), an endangered raptor that preys on the native Florida apple snail (Beissinger, Donnay & Walton, 1994; Burks, Miller & Hill, 2020).

Organic Matter Decomposition in River Ecosystems: Microbial Interactions Influenced by Total Nitrogen and Temperature in River Water

Article

Full-text available

May 2022
MICROB ECOL

Microbes contribute to the organic matter decomposition (OMD) in river ecosystems. This study considers two aspects of OMD in river ecosystems which have not been examined in scientific studies previously, and these are the microbial interactions in OMD and the influence of environmental factors on microbial interactions. Cotton strip (CS), as a substitute for organic matter, was introduced to Luanhe River Basin in China. The results of CS assay, microbial sequencing, and redundancy analysis (RDA) showed that CS selectively enriched bacterial and fungal groups related to cellulose decomposition, achieving cotton strip decomposition (CSD). Bacterial phylum Proteobacteria and fungal phyla Rozellomycota and Ascomycota were the dominant groups associated with CSD. Network analysis and Mantel test results indicated that bacteria and fungi on CS cooperatively formed an interaction network to achieve the CSD. In the network, modules 2 and 4 were significantly positively associated with CSD, which were considered as the key modules in this study. The key modules were mainly composed of phyla Proteobacteria and Ascomycota, indicating that microbes in key modules were the effective decomposers of CS. Although keystone taxa were not directly associated with CSD, they may regulate the genera in key modules to achieve the CSD, since some keystone taxa were linked with the microbial genera associated with CSD in the key modules. Total nitrogen (TN) and temperature in water were the dominant environmental factors positively influenced CSD. The key modules 2 and 4 were positively influenced by water temperature and TN in water, respectively, and two keystone taxa were positively associated with TN. This profoundly revealed that water temperature and TN influenced the OMD through acting on the keystone taxa and key modules in microbial interactions. The research findings help us to understand the microbial interactions influenced by environmental factors in OMD in river ecosystems.

17. Conservation and Ecological Rehabilitation of North American Desert Spring Ecosystems

Chapter

Full-text available

Jan 2021

Unusual waterscapes and precarious rural livelihoods: Occurrence, utilisation and conservation of springs in the Save Catchment, Zimbabwe

Thesis

Dec 2018

David Chikodzi

Springs are an important natural resource in many rural spaces which, if utilised sustainably, can be an important source of livelihoods for rural communities. In Zimbabwe, the social aspects of springs and their waterscapes remain understudied. This includes an in-depth understanding of how communities have shaped their livelihoods around springs, the extent to which they have contributed to sustainable rural livelihoods, especially in water stressed parts of the country and the institutional framework shaping their access and utilisation. Using the sustainable livelihoods framework of analysis, the goal of this study was to investigate the role that springs and their resultant waterscapes have played in securing livelihoods for rural households in the Save Catchment of Zimbabwe. Methodologically, the research adopted the socio-hydrological approach which is a new and emerging discipline that aims at understanding the interactions and feedbacks between the human and natural processes that give rise to community water sustainability challenges. The socio-hydrological approach is informed by both the qualitative and quantitative research techniques of data collection and analysis. Two rural communities (Nyanyadzi and Maturure) of the Save Catchment were randomly selected for an in-depth study. The snowball sampling technique (non-probability) was utilised in the selection of the 100 participants for the questionnaire survey. Purposive sampling was used to select nine key informant interview participants. Secondary data collection was done through a systematic review of scholarly and policy literature. Qualitative data generated from primary and secondary sources were processed and analysed using qualitative techniques such as thematic ordering, systematisation and fine grain analysis. For quantitative data, descriptive statistics, such as frequencies, were used to summarise and analyse questionnaire data. Rural communities in the Save Catchment of Zimbabwe were observed to have developed livelihood strategies that were anchored on springs and their waterscapes. In the studied communities, springs were utilised for both commercial and subsistence purposes and livelihoods constructed around springs included; gardening, tourism, livestock production, brick kilning art and craft making. In the study, springs were also shown to be a very important component of sustainable rural livelihoods. However, most of them were perceived to be declining in both water quality and quantity, imposing complex livelihood conundrums for the rural communities and threatening the sustainability of livelihood strategies that they are supporting. Practices observed to be threatening the integrity of springs were encroachment of settlements, natural environmental changes, soil erosion and population pressure. Limited environmental awareness, poverty, poor implementation and enforcement of conservation laws has resulted in the adoption of practices that degraded springs. Institutions shaping spring utilisation were observed to be ineffective to a large extent due to lack of capacities and conflicting mandates but local traditional leadership and water committees were observed to have deeper community penetration and were the most effective in influencing access and effective management of springs and their related waterscapes.

Combined carbon flows through detritus, microbes, and animals in reference and experimentally enriched stream ecosystems

Article

Full-text available

Feb 2021
ECOLOGY

Tracking carbon (C) flow through ecosystems requires quantification of myriad biophysical processes, including C routing through microbial and metazoan food webs. Yet detailed organic matter budgets are rarely combined with simultaneous measurement of C flows supporting microbial and animal production. Here, we synthesize concurrent data sets on organic matter, microbes, and macroinvertebrates from two detritus‐based stream ecosystems, one of which was subject to experimental nitrogen (N) and phosphorus (P) enrichment. Our synthesis provides new insights into C flow through forest stream ecosystems. Over 3 yr, the reference stream showed a striking balance of inputs and outputs, with a mean surplus of only 7 g C·m⁻²·yr⁻¹ (~1% of annual inputs), presumably stored in sediments as fine particulate organic matter (FPOM). In contrast, N and P enrichment over 2 yr resulted in severe deficits of C (−576 g C·m⁻²·yr⁻¹ or ~170% of annual inputs), a shortfall presumably met by stored C. Our data set provides an ecosystem‐based estimate of the fate of forest litter C at ambient nutrient concentrations: 6.2% was leached as dissolved organic C, 40.6% and 8.5% flowed to litter‐associated fungi and bacteria, respectively, 7.5% was consumed by macroinvertebrates, 1.8% was exported as coarse particles, and the remainder (35.4%) was presumably fragmented by biophysical processes. Our calculations also allowed an estimate of inputs into the heterogeneous FPOM pool, which is otherwise difficult to obtain. At naturally low nutrient concentrations, 50.7% was derived from fragmented litter, 39.1% from microbial biomass (mostly fungal), and 10.2% from macroinvertebrate egesta. Nutrient addition drove large changes in C fluxes in the experimental stream, especially in flows of leaf litter to fungi (×1.7 pretreatment) and macroinvertebrates (×2.7), and of FPOM to hydrologic export (×2.6). Our results underscore the key roles of both microbes and metazoans in controlling C flow through detritus‐based ecosystems, as well as how release from persistent nutrient limitation may perturb steady‐state conditions of C inputs vs. outputs. Our analysis also suggests areas for future research, including assessing the relative importance of stored vs. recycled C in fueling detrital food webs subject to altered nutrient regimes and other global‐change drivers.

Nitrate depletion dynamics and primary production in riverine benthic chambers

Article

Full-text available

Jan 2020

Characteristics, Main Impacts, and Stewardship of Natural and Artificial Freshwater Environments: Consequences for Biodiversity Conservation

Article

Full-text available

Jan 2020

In this overview (introductory article to a special issue including 14 papers), we consider all main types of natural and artificial inland freshwater habitas (fwh). For each type, we identify the main biodiversity patterns and ecological features, human impacts on the system and environmental issues, and discuss ways to use this information to improve stewardship. Examples of selected key biodiversity/ecological features (habitat type): narrow endemics, sensitive (groundwater and GDEs); crenobionts, LIHRes (springs); unidirectional flow, nutrient spiraling (streams); naturally turbid, floodplains, large-bodied species (large rivers); depth-variation in benthic communities (lakes); endemism and diversity (ancient lakes); threatened, sensitive species (oxbow lakes, SWE); diverse, reduced littoral (reservoirs); cold-adapted species (Boreal and Arctic fwh); endemism, depauperate (Antarctic fwh); flood pulse, intermittent wetlands, biggest river basins (tropical fwh); variable hydrologic regime-periods of drying, flash floods (arid-climate fwh). Selected impacts: eutrophication and other pollution, hydrologic modifications, overexploitation, habitat destruction, invasive species, salinization. Climate change is a threat multiplier, and it is important to quantify resistance, resilience, and recovery to assess the strategic role of the different types of freshwater ecosystems and their value for biodiversity conservation. Effective conservation solutions are dependent on an understanding of connectivity between different freshwater ecosystems (including related terrestrial, coastal and marine systems).

Ecohydrogeology: The interdisciplinary convergence needed to improve the study and stewardship of springs and other groundwater-dependent habitats, biota, and ecosystems

Article

Mar 2020
ECOL INDIC

Ecology, thermodynamics and H.T. Odum's conjectures

Article

Full-text available

Jan 1993

The central role of energy in all life processes has led to the development of numerous hypotheses, conjectures and theories on the relationships between thermodynamics and ecological processes. In this paper we examine the theoretical and empirical support for these developments, and in particular for the widely published set of thermodynamic conjectures developed by H.T. Odum, in which the maximum power principle is put forward as a generic feature of evolution in ecosystems. Although they are widely used, we argue that many of the ecological studies that have adopted the ideas encapsulated in Odum's work have done so without being aware of some of the fundamental problems underlying this approach. We discuss alternative ways in which a general available-work concept could be constructed for use as a numeraire in an energy-centered ecological theory or paradigm. In so doing, we examine what is meant by material accessibility and energy stocks and flows with respect to traditional food web and food chain theories, and relate these to results from the evolutionary dynamics of ecosystems. We conclude that the various forms and uses of energy bound up in essential ecosystem processes present a formidable obstacle to obtaining an operational definition of a general, aggregated available-work concept, a prerequisite for the systems approach of Odum and others. We also show that the prototypical derivations of the maximum power principle, and its interpretation, are contradicted on many scales both by empirical data and models, thereby invalidating the maximum power principle as a general principle of ecological evolution. The conclusions point to the fundamental problem of trying to describe ecosystems in a framework which has a one-dimensional currency.

Population dynamics of Pistia stratiotes L.

Article

Full-text available

Apr 2019

Pistia stratiotes is one of the worst weeds in the world, and it adversely affects the environment and biodiversity. A large gap remains in the quantitative knowledge about the growth, biomass and life cycle of this invasive macrophyte under natural conditions in Egypt. Therefore, this study aims to determine the monthly variation in P. stratiotes population dynamics in the South Nile Delta (Egypt) to identify the potential weak stages in the species’ life cycle and thereby suggest the best time to begin control of this invasive species. Sampling was performed monthly from May 2013 to February 2014 at three sites along the Al-Sero Drain; three randomly distributed quadrats (each of 0.5 × 0.5 m) were used at each site. Generally, the Al-Sero Drain is characterized by having alkaline, brackish and moderately eutrophic waters. The shoot systems started to grow in May, reached their maximum biomass of 320.7 g DM m⁻² in September and then decreased and reached their lowest value in February. The root biomass increased from 2.3 g DM m⁻² in May to 26.6 g DM m⁻² in August and decreased to a minimum of 4.9 g DM m⁻² in February. The relative growth rate of the plant was highest during the summer, whereas the lowest relative growth rate occurred in the winter. In conclusion, to suppress or eradicate this macrophyte from a drain, the harvest should be performed in May, when the biomass is low, and the offshoot production is just beginning (before the formation of large mature individuals).

Challenges and Environmental Impacts of Biomass Energy in South Asia

Article

Apr 2019

Plants utilise solar energy to synthesise food during photosynthesis as it provides biomaterials needed for generation of bio-energy. A byproduct of natural and biological sources can be used as a source of bioenergetics; it is a good replacement for carbon energy or fossil fuel. In this article, a variety of biomasses, its impacts on the environment and challenges in production are discussed coherently. This study focuses on the advantages and disadvantages of Biomass-derived fuels and its utilisation in Asia. Production of Sugarcane, Palm oil and Sorghum is compared among all Asian countries. Current research on palm oil effluents revealed that oil palm was a more energy friendly crop and oil palm cultivation under current practices posed no risk to the environment. Comparative reports on consumption of fuels and Biomass trade have been discussed Introduction of four fuel and fifth fuel strategy ensure reliability and security of energy supply which includes petroleum, natural gas, hydropower and coal to reduce consumption of petroleum. In Malaysia, Petroleum dependence has been drastically reduced from 98% in 1980 to 8% in 1999. Recently, fifth fuel renewable energy is introduced by government which provide an alternative to the other sources of energy. Biomass fuels are a sustainable, efficient and viable source of energy. It can be generated from a waste material which also provides an efficient way of waste management. Countries with high agricultural resources can look forward to biomass energy production. In the coming years, biomass energy will be a small but significant part of the energy. This may be beneficial in increasing the economy of a country. Biomass energy can be achieved with a high success rate with the help of advanced technology, effective government policies, and international trade.

Ecosystem spatial self-organization: Free order for nothing? ☆

Article

Feb 2019
ECOL COMPLEX

Ecosystems are complex adaptive systems (CAS) by nature, which means that macroscopic patterns and properties emerge from, and feed back to affect, the interactions among adaptive individual ecological agents. These agents then further adapt (genetically) to the outcomes of those interactions. The concept of self-organization has become increasingly important for understanding ecosystem spatial heterogeneity and its consequences. It is well accepted that ecosystems can self-organize, and that resulting spatial structures carry functional consequences. Feedbacks from the outcome of spatial pattern to the individual agents from which patterns emerge, are an essential component of the definition of CAS but have been rarely examined for ecosystems. We explore whether spatial self-organization provides a mechanism for such feedback for ecosystems as CAS, that is, whether ecosystem-level outcomes of self-organized patterning could feed back to affect or even reinforce local pattern-forming processes at the agent level. Diffuse feedbacks of ecological and evolutionary significance ensue as a result of spatial heterogeneity and regular patterning, whether this spatial heterogeneity results from an underlying template effect or from self-organization. However, feedbacks directed specifically at pattern-forming agents to enhance pattern formation-reinforcing feedback-depend upon the level of organization of agents. Reinforcing evolutionary feedbacks occur at the individual level or below. At the ecosystem level, evidence for mechanisms of feedback from outcomes to patterning to agents forming the patterning remain tenuous. Spatial self-organization is a powerful dynamic in ecosystem and landscape science but feedbacks have been only loosely integrated so far. Self-organized patterns influencing dynamics at the ecosystem level represent "order for free". Whether or not this free order generated at the ecosystem level carries evolutionary function or is merely epiphenomenal is a fundamental question that we address here.

A modification of the leaf-bags method to assess spring ecosystem functioning: Benthic invertebrates and leaf-litter breakdown in Vera Spring (Central Italy)

Article

Full-text available

Feb 2019

The evaluation of leaf detritus processing (decomposition and breakdown) is one of the most simple and cost-effective method to assess the functional characteristics of freshwater ecosystems. However, in comparison with other freshwater habitats, information on leaf litter breakdown in spring ecosystems is still scarce and fragmentary. In this paper, we present results of the first application of a variant of the leaf-bags method to assess structure of macroinvertebrate assemblages and leaf-litter breakdown in a Central Apennines (Italy) cold spring which was investigated from July 2016 to October 2016. Notwithstanding the stable conditions of almost all hydrological and physico-chemical parameters, we found significant temporal differences in (i) % of mass loss of poplar leaves (ii) number of Ephemeroptera, Plecoptera and Trichoptera taxa, (iii) shredder and predator densities. We demonstrate that detritus processing in cold springs may be faster than or as fast as in warmer streams/rivers. Shredders activity and biocoenotic interactions, rather than temperature and nutrients load, were the main drivers of the process. A routine application of the modified leaf-bags may contribute to expand our knowledge on detritus processing in cold springs and may help to predict impacts of climate warming on freshwater ecosystem functioning.

“Unifying” the Concept of Resource Use Efficiency in Ecology

Article

Full-text available

Jan 2019

Resource use efficiency (RUE) is an ecological concept that measures the proportion of supplied resources, which is converted into new biomass, i.e., it relates realized to potential productivity. It is also commonly perceived as one of the main mechanisms linking biodiversity to ecosystem functioning based on the assumption that higher species numbers lead to more complementary and consequently more efficient use of the available resources. While there exists a large body of literature lending theoretical and experimental support to this hypothesis, there are a number of inconsistencies regarding its application: First, empirical tests use highly divergent approaches to calculate RUE. Second, the quantification of RUE is commonly based on measures of standing stock instead of productivity rates and total pools of nutrients instead of their bioavailable fractions, which both vary across systems and therefore can introduce considerable bias. Third, conceptual studies suggest that the relationship between biodiversity, productivity and RUE involves many more mechanisms than complementary resource use, resulting in variable magnitude and direction of biodiversity effects on productivity. Moreover, RUE has mainly been applied to single elements, ignoring stoichiometric, or metabolic constraints that lead to co-limitation by multiple resources. In this review we illustrate and discuss the use of RUE within and across systems and highlight how the various drivers of RUE affect the diversity-productivity relationship with increasing temporal and spatial scales as well as under anthropogenic global change. We illustrate how resource supply, resource uptake and RUE interactively determine ecosystem productivity. In addition, we illustrate how in the context of biodiversity and ecosystem functioning, the addition of a species will only result in more efficient resource use, and consequently, higher community productivity if the species' traits related to resource uptake and RUE are positively correlated.

Mayfly ecological traits in a European karst spring: Species, microhabitats and life histories

Article

Dec 2018

Despite the recent increase in the number of mayfly studies in karst freshwater habitats, their biology and ecology in springs are still poorly characterized. Therefore, we studied mayfly assemblages in a European karst rheocrene spring at five microhabitats monthly over a one-year period. Three species were recorded: Baetis alpinus (Pictet, 1843), Baetis rhodani (Pictet, 1843) and Rhithrogena braaschi (Jacob, 1974). The latter species represents a new record for the fauna of Bosnia and Herzegovina. All three species inhabited all studied microhabitats but with varying abundance. Individual species were associated with a specific substrate type and/or water velocity and/or water depth. The grazer/scraper Rh. braaschi was most common at microhabitats with inorganic substrate (cobbles, mixture of pebbles and sand), moderate water velocity and higher water depth. The rheophilic grazer/scraper and gatherer/collector B. alpinus was most common at microhabitats with mosses and highest water velocity. The grazer/scraper and gatherer/collector B. rhodani was recorded at all microhabitats, yet due to its preference for moderate water velocity, the highest number of individuals were collected from cobbles. We recorded movements of mayfly nymphs among the available microhabitats during their life cycles, due likely to their dietary requirements and search for suitable refugia. Baetis alpinus has a bivoltine, B. rhodani polyvoltine and Rh. braaschi univoltine life cycle with a long emergence period. The results presented here contribute to the knowledge of spring and mayfly ecology.

New insights to be gained from a Virtual Ecosystem

Preprint

Jun 2024

The myriad interactions among individual plants, animals, microbes and their abiotic environment generate emergent phenomena that will determine the future of life on Earth. Here, we argue that holistic ecosystem models – incorporating key biological domains and feedbacks between biotic and abiotic processes – capable of predicting emergent phenomena are required if we are to understand the functioning of complex, terrestrial ecosystems in a rapidly changing planet. We argue that holistic ecosystem models will provide a framework for integrating the many approaches used to study ecosystems, including biodiversity science, population and community ecology, soil science, biogeochemistry, hydrology and climatology. Holistic models will provide new insights into the nature and importance of feedbacks that cut across scales of space and time, and that connect ecosystem domains such as microbes and animals or above and below ground. They will allow us to critically examine the origins and maintenance of ecosystem stability, resilience and sustainability through the lens of systems theory, and provide a much-needed boost for conservation and the management of natural environments. We outline our approach to developing a holistic ecosystem model – the Virtual Ecosystem – and argue that while the construction of such complex models is obviously ambitious, it is both feasible and necessary.

MODELING ALGAL TURF SCRUBBER (ATS) FOR LARGE-SCALE APPLICATION

Technical Report

Full-text available

Sep 2001

This paper provides a method for Modeling Algal Turf Scrubber® (ATS) systems for large-scale applications. As with many biological water treatment processes, the dynamics associated with the ATS - an attached algae technology - can be described as a first-order reaction, where the rate of reaction is proportional to the concentration of the substrate. Within sustainable biological processes, in which biomass removal allows long-term stabilization of the chemical and physical environment, it is possible to orient the first-order reaction around the principal mechanism involved in nutrient removal -that being biomass productivity. In some cases, modeling of this productivity can target a dominant species, such as with floating aquatic plant systems like the Water Hyacinth Scrubber technology. However, in most cases, the application of growth models is applied to a set community of involved organisms, such as with activated sludge, fixed film technology, fermentation and ATS.

Composition of Photosynthetic Gas Bubbles From Submerged Macrophytes

Article

Full-text available

Jan 2024
WATER RESOUR RES

Dissolved oxygen plays a central role for all organisms dwelling in water. However, the flux of oxygen by ebullition has not received much attention in environmental science. For a better quantitative understanding of the oxygen flux due to ebullition, we conducted a series of laboratory experiments, where we forced macrophytes to produce photosynthetic gas bubbles. Raising the CO2 concentration in the water greatly increased bubble formation. Depth was varied to compare the results with theoretically predicted composition of photosynthetic bubbles forming at minimum required gas pressure. Oxygen concentrations lay between this theoretical line as lower boundary (ca. 21% O2 at 0.3 m depth and 45% of O2 at 4.5 m) and 45% of oxygen as the purely empirical upper limit for all depths. As a consequence, no bubble formation was observed at depths below 4.5 m.

Aquaculture Mapping in the Context of Climate Change

Chapter

Apr 2023

Yunwei Dong

The development of aquaculture is facing unprecedented pressures from climate change, resource constraints, environmental pollution, energy consumption, and other factors. For coping with these challenges and for ensuring sustainable development of aquaculture, spatial planning in aquaculture activities become more and more important. An ecosystem-based approach for aquaculture mapping is needed to strategically and comprehensively balance the location, aquaculture type, and stakeholders’ interests. In this chapter, we aim to describe the definition, key steps, and methods of aquaculture zoning, especially in the context of climate change (e.g., global warming, ocean acidification, hypoxia/anoxia, sea level rising, and extreme events). We also provide two case studies of aquaculture mapping in China.

Sustainability of Aquaculture Production Systems

Chapter

Apr 2023

Agricultural practice of the world in last decades has proved that simplistic intensification of agriculture systems has paid high prices while increasing crop production and production efficiency. Therefore, sustainable intensification should be a pattern for the development of aquaculture. The goal of sustainable development of aquaculture systems can be achieved through the ecological intensification, that is, integrating anthropogenic inputs with aquaculture ecosystem services. This chapter will introduce the multidimensionality of aquaculture systems, and the relationships of intensification degree with economic efficiency and ecological footprints, so that we can better understand the sustainability of aquaculture systems and the future development pattern of aquaculture industry.

Disentangling In‐Stream Nitrate Uptake Pathways Based on Two‐Station High‐Frequency Monitoring in High‐Order Streams

Article

Full-text available

Mar 2023
WATER RESOUR RES

In‐stream nitrate (NO3⁻) uptake in rivers involves complex autotrophic and heterotrophic pathways, which often vary spatiotemporally due to biotic and abiotic drivers. High‐frequency monitoring of NO3⁻ mass balance between upstream and downstream measurement sites can quantitatively disentangle multi‐path NO3⁻ uptake dynamics at the reach scale. However, this approach remains limited to a few river types and has not been fully explored for higher‐order streams with varying hydro‐morphological and biogeochemical conditions. We conducted two‐station 15‐min monitoring in five high‐order stream reaches in central Germany, calculating the NO3⁻‐N mass balance and whole‐stream metabolism based on time series of NO3⁻‐N and dissolved oxygen, respectively. With thorough considerations of lateral inputs, the calculated net NO3⁻‐N uptake rates (UNET ${U}_{\mathrm{N}\mathrm{E}\mathrm{T}}$) differed substantially among campaigns (ranging from −151.1 to 357.6 mg N m² d⁻¹, with cases of negative values representing net NO3⁻‐N release), and exhibited higher UNET ${U}_{\mathrm{N}\mathrm{E}\mathrm{T}}$ during the post‐wet season than during the dry season. Subtracting autotrophic assimilation (UA ${U}_{A}$, stoichiometrically coupled to stream metabolism) from UNET ${U}_{\mathrm{N}\mathrm{E}\mathrm{T}}$, UD ${U}_{D}$ represented the net balance of heterotrophic NO3⁻‐N uptake (UD ${U}_{D}$ > 0, the dominance of denitrification and heterotrophic assimilation) and NO3⁻‐N release (UD ${U}_{D}$ < 0, the dominance of nitrification/mineralization). This rarely reported uptake pathway contributed substantially to UNET ${U}_{\mathrm{N}\mathrm{E}\mathrm{T}}$ patterns, especially during post‐wet seasons; moreover, it appeared to exhibit various diel patterns, and for UD ${U}_{D}$ > 0, diel minima occurred during the daytime. These findings advance our understanding of complex reach‐scale N‐retention processes and can help develop future modeling concepts at the river‐network scale.

Preliminary Engineering Assessment for a Comprehensive Algal Turf Scrubber® (ATS™) Based Nutrient Control Program for the Suwannee River in Florida

Technical Report

Full-text available

Aug 2006

This document has been prepared by HydroMentia, Inc., at the request of SRWMD, as an initial assessment of the application of the Algal Turf Scrubber® (ATS™) technology as a regional treatment system to meet nitrogen reduction goals. Conceptual locations for the 11 treatment sites are included in the report. The eleven sites included a total of 120 treatment modules, with a total effective treatment area of 1440 acres. The total projected removal for nitrate-nitrogen is 1,285 tons per year (tpy) or 29.3% of the total nitrate load discharge from the Suwannee River (just under the target of 30%); 1,922 tpy for total nitrogen or 23.0% of the total load; and 356 tpy for total phosphorus or 47.6% of the total load. Life Cycle Cost Analysis (LCCA) is provided as a measure for comparing long-term cost-effectiveness to other available technologies and system processes. The Present Value Cost per pound of nitrate nitrogen, total nitrogen and total phosphorus removed were determined to be $9.76/lb-nitrate-nitrogen; $6.57/lb-total nitrogen; and $35.16/lb-total phosphorus.

River Corridor Sources Dominate CO2 Emissions From a Lowland River Network

Article

Full-text available

Jan 2023

Rivers and streams are control points for CO2 emission to the air (fCO2), with emission rates often exceeding internal metabolism (net ecosystem production, NEP). The difference is usually attributed to CO2‐supersaturated groundwater inputs from upland soil respiration and rock weathering, but this implies a terrestrial‐to‐aquatic C transfer greater than estimated by terrestrial mass balance. One explanation is that riparian zones—rich in organic and inorganic C but mostly neglected in terrestrial mass balances—contribute disproportionately to fCO2. To test this hypothesis, we measured fCO2, NEP, and the lateral CO2 contributions from both terrestrial uplands (TER) and riparian wetlands (RIP) for seven reaches in a lowland river network in Florida, USA. NEP contributed about half of fCO2, but the remaining CO2 emission was generally much larger than measured TER. The relative importance of RIP versus TER varied markedly between contrasting hydrogeologic settings: RIP contributed 49% of fCO2 where geologic confinement forced lateral drainage through riparian soils, but only 12% where unconfined karst allowed deeper groundwater flowpaths that bypassed riparian zones. On a land area basis, the narrow riparian corridor yielded far more CO2 than the terrestrial uplands (33.1 vs. 1.4 g‐C m⁻² yr⁻¹), resulting in river corridors (i.e., stream channel plus adjacent wetlands, NEP + RIP) sourcing 87% of fCO2 to streams. Our findings imply that true terrestrial CO2 subsidies to streams may be smaller than previously estimated by aquatic mass balance and highlight the importance of explicitly integrating riparian zones into the conceptual model for terrestrial‐to‐aquatic C transfer.

Setting Benthic Algal Abundance Targets to Protect Florida Spring Ecosystems

Chapter

Oct 2022

Robert A. Mattson

The establishment of quantitative targets for algal abundance in lakes (usually expressed as water column chlorophyll a concentration in μg/L) is well‐ensconced in lake management. Setting targets for abundance of benthic/attached algae in streams has not garnered as much attention in stream ecology and management. Establishment of targets for benthic algae in streams is in part dependent upon the particular attribute that is to be protected, including water withdrawal/water supply, aesthetics, recreation, or ecosystem protection. Abundance targets may be expressed as % cover, chlorophyll a density (as mg Chl a per unit area), or standing crop (g dry weight or ash‐free dry weight per unit area). This chapter will review benthic algal abundance targets proposed in the stream literature and compare them with epiphytic and macroalgal abundance measured in a 2015 study of 14 spring‐run streams in Florida. Various investigators have proposed quantitative targets based on either mean/median or maximum algal abundance. Efforts in temperate streams have suggested macroalgal targets of 20%–40% cover, 100–150 mg/m 2 chlorophyll a density, or 40 g/m 2 ash‐free dry weight (AFDW). These targets were mainly based on aesthetics and recreational issues and may or may not be relevant for Florida spring‐run streams, but they may be adopted as a starting point. Given the changes in benthic algal abundance seen in Florida spring‐run streams over the past few decades, establishing targets for algal abundance to guide restoration attempts appears to be warranted.

Assessing Pollution and Depletion of Large Artesian Springs in Florida's Rapidly Developing Water‐Rich Landscape

Chapter

Oct 2022

The area of north and central Florida has one of the largest concentrations of large artesian springs in the world. These springs and the rivers they create, including their productive and highly adapted biota, are dependent upon flows of groundwater from the Floridan aquifer, fed by rainfall recharge over a land area of about 100,000 square miles. The Floridan aquifer is also the source of water used for drinking, irrigation, and commercial/industrial industries by more than 14 million people. Human uses of the region's groundwater are in direct conflict with spring flows resulting in long‐term flow reductions for the majority of Florida's springs. In addition to this water quantity issue, human activities, including the use of nitrogen fertilizers and disposal of human and animal wastewaters, have polluted a large portion of the Floridan aquifer with nitrogen, implicated in springs eutrophication evidenced by loss of native vegetation and replacement by filamentous algae. While these impairments have been recognized for more than 20 years and are the subject of state efforts to protect spring flows and water quality, conditions are worsening in most springs. The Blue Water Audit is a GIS‐based tool that quantifies the sources of water quantity and quality stresses on a parcel‐by‐parcel basis to facilitate the prioritization of restoration actions. Web‐based dissemination of this “aquifer footprint” information is helping to highlight these issues for the public and its elected representatives.

A History of Radioecology

Book

Nov 2022

Patrick C. Kangas

Les concepts fondamentaux de la synécologie quantitative

Article

Jan 1962

Watershed-scale Land Use Change Increases Ecosystem Metabolism in an Agricultural Stream

Article

Full-text available

Jun 2021
ECOSYSTEMS

Stream metabolism, in the form of gross primary production (GPP) and ecosystem respiration (ER), is an important metric of stream ecosystem function, given GPP and ER are integrative measurements of basal ecosystem activity that are highly sensitive to environmental change. In agricultural streams of temperate North America GPP can be mediated by water column turbidity associated with soil erosion during periods when the terrestrial landscape is bare (that is, typically late fall through spring; Oct–May in N America). We estimated a 10-year time series of stream metabolism using continuous dissolved oxygen measurements in an agricultural watershed (Shatto Ditch, IN), comparing metabolism metrics before and after vegetative cover was added to fields during normally fallow periods when they would otherwise be bare. Adding vegetative cover reduced water column turbidity by 54% during days with high precipitation (upper 25th percentile). We also found that GPP varied seasonally with light and temperature (range = 0.1–17.2 g m−2 d−1) and increased significantly in spring with landscape vegetative cover addition. Finally, we used a subset of storms to show that turbidity was lower and GPP was higher during storms after adding watershed vegetative cover, suggesting that increased GPP could be attributed to increased light availability with less turbid water. We found that ER also increased after adding vegetative cover, which we attribute, in part, to increased autotrophic respiration. These results suggest that water turbidity is a mediating driver of stream metabolism, particularly when other primary drivers are not limiting GPP. Likewise, stream turbidity can be mediated by land cover on the surrounding watershed, demonstrating a clear linkage between land use and stream metabolic signatures.

Construct social-behavioral association network to study management impact on waterbirds community ecology using digital video recording cameras

Article

Full-text available

Feb 2021

Studying social‐behavior and species associations in ecological communities is challenging because it is difficult to observe the interactions in the field. Animal behavior is especially difficult to observe when selection of habitat and activities are linked to energy costs of long‐distance movement. Migrating communities tend to be resource specific and prefer environments that offer more suitability for coexisting in a shared space and time. Given the recent advances in digital technologies, digital video recording systems are gaining popularity in wildlife research and management. We used digital video recording cameras to study social interactions and species–habitat linkages for wintering waterbirds communities in shared habitats. Examining over 8,640 hr of video footages, we built tetrapartite social‐behavioral association network of wintering waterbirds over habitat (n = 5) selection events in sites with distinct management regimes. We analyzed these networks to identify hub species and species role in activity persistence, and to explore the effects of hydrological regime on these network characteristics. Although the differences in network attributes were not significant at treatment level (p = .297) in terms of network composition and keystone species composition, our results indicated that network attributes were significantly different (p = .000, r² = .278) at habitat level. There were evidences suggesting that the habitat quality was better at the managed sites, where the formed networks had more species, more network nodes and edges, higher edge density, and stronger intra‐ and inter‐species interactions. In addition, we also calculated the species interaction preference scores (SIPS) and behavioral interaction preference scores (BIPS) of each network. The results showed that species synchronize activities in shared space for temporal niche partitioning in order to avoid or minimize any potential competition for shared space. Our social network analysis (SNA) approach is likely to provide a practical use for ecosystem management and biodiversity conservation.

Trematode parasites exceed aquatic insect biomass in Oregon stream food webs

Article

Full-text available

Jan 2021
J ANIM ECOL

Although parasites are increasingly recognized for their ecosystem roles, it is often assumed that free‐living organisms dominate animal biomass in most ecosystems and therefore provide the primary pathways for energy transfer. To examine the contributions of parasites to ecosystem energetics in freshwater streams, we quantified the standing biomass of trematodes and free‐living organisms at nine sites in three streams in western Oregon, USA. We then compared the rates of biomass flow from snails Juga plicifera into trematode parasites relative to aquatic vertebrate predators (sculpin, cutthroat trout and Pacific giant salamanders). The trematode parasite community had the fifth highest dry biomass density among stream organisms (0.40 g/m²) and exceeded the combined biomass of aquatic insects. Only host snails (3.88 g/m²), sculpin (1.11 g/m²), trout (0.73 g/m²) and crayfish (0.43 g/m²) had a greater biomass. The parasite ‘extended phenotype’, consisting of trematode plus castrated host biomass, exceeded the individual biomass of every taxonomic group other than snails. The substantial parasite biomass stemmed from the high snail density and infection prevalence, and the large proportional mass of infected hosts that consisted of trematode tissue (M = 31% per snail). Estimates of yearly biomass transfer from snails into trematodes were slightly higher than the combined estimate of snail biomass transfer into the three vertebrate predators. Pacific giant salamanders accounted for 90% of the snail biomass consumed by predators. These results demonstrate that trematode parasites play underappreciated roles in the ecosystem energetics of some freshwater streams.

Trophische Beziehungen

Chapter

Sep 2017

Der Artikel enthält folgende Kapitel: Einleitung Allgemeine Aspekte Trophische Beziehungen in terrestrischen Ökosystemen Trophische Beziehungen in limnischen Ökosystemen Resümee Zitierte Literatur Glossar

Hydrodynamic Controls on Primary Producer Communities in Spring-Fed Rivers

Article

Full-text available

May 2019
GEOPHYS RES LETT

Plain Language Summary Spring‐fed rivers are ecologically, socially, and economically important ecosystems. In many springs, algae has been increasing—and in some cases replacing—submerged plants, with negative ecosystem impacts. Restoring springs requires an improved understanding of the drivers of plant and algae abundance. In this study, we investigated the relationship between the speed of flowing water and the abundance of plant and algae using two approaches. First, we used observations of water speed and plant and algal abundances from 16 springs to determine if there was a critical flow speed above which plants and algae decreased. Second, we performed field experiments where we artificially reduced water speed, allowing algae to grow on submerged plants, and then quantified its growth and removal rates. The observational study showed that algae growing on plants (periphyton) is reduced at flow speeds above ~0.22 m/s. In contrast, submerged plants and algae growing on the river bottom did not have identifiable thresholds. The experimental study and theoretical calculations agreed with these results and identified the mechanism for this threshold. Finally, we found that increased algae abundance returns to its previous state when flow is restored, suggesting that restoring water flows can also help reduce algal levels in impacted springs.

Food Losses through Energy Transfer from Cereal Grains to Stored-Product Insects

Article

Apr 1982

R.N. Sinha

Trophic Structure and Productivity of Silver Springs, Florida

No full-text available

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