Scales of spatial patterns of distribution of intertidal snails

Estructura y diversidad del ensamblaje de bivalvos en bahía de Mazatlán, México, con énfasis en el estudio del crecimiento y reproducción de Donax punctatostriatus

Thesis

Jul 2015

María del Carmen Esqueda-González

Esta tesis aborda la biología y ecología de los moluscos bivalvos de la bahía de Mazatlán, México. Los tres primeros capítulos (I, II, III) se refieren a la ecología del ensamblaje de bivalvos y los dos últimos (IV, V) a la estructura y dinámica poblacional de la almeja coquina Donax punctatostriatus. Este bivalvo fue elegido como caso de estudio para profundizar en la biología y ecología poblacional de una de las especies representativas de la región y por un recurso potencial (actualmente no es explotada) del cual no existe información previa. Este trabajo incluye aportaciones importantes al conocimiento de la biología y ecología de los bivalvos de bahía de Mazatlán, basadas no solamente en el uso de diferentes metodologías y enfoques analíticos integrales y actuales sino, en una visión innovadora que no ha sido implementado para el estudio de los ensamblajes de especies de una bahía en particular. El documento se articula mediante apartados (capítulos) que van desde lo descriptivo a lo analítico de manera que los resultados de capítulo sirven de base para los subsiguientes. Por supuesto todo este esfuerzo está sujeto al escrutinio de biólogos especialistas y se podrán desprender quizás más preguntas que respuestas sobre la biología y ecología de los bivalvos de esta región del mundo, lo cual hace aún más interesante su lectura y revisión

The role of topographic complexity in the structure and dynamics of rocky shore communities

Thesis

Jan 2001

Natalie J. Frost

p>The overall aim of this work was to assess the importance of topographic complexity in structuring rocky shore communities. In order to achieve this the distributions of intertidal species were related to physically and biologically generated features of the habitat. In addition manipulative experiments were used to gain a more complete understanding of the processes in operation. Initially a review of the methods and indices used to measure habitat complexity was made. Three methods were compared using field trials: stereophotography, profile gauges and lengths of chain contoured over the substratum. Chains were the most efficient method to use, followed by stereophotography and profile gauges respectively. The results derived from the chain method and profile gauges were directly related, but stereophotography results were not comparable. Stereophotography, correlations between topographic features and the distribution of the overlying biota. This led to the development of an automated technique that directly linked these parameters. The strongest correlations between topographic features and biological distributions were typically observed for algal species. The influence of complexity, however, varied across a number of scales depending on the species examined. however, offered the additional benefit of allowing direct Both physical and biological complexity was demonstrated to have an important role in structuring rocky shore communities. Details of the recruitment of algae and sessile invertebrates to substrata of varying complexity were first examined. In order to achieve this the topography of the substratum was manipulated by the use of concrete blocks cast with differing surface features. The succession of intertidal communities was also observed on mussel beds. The recruitment of algae did not appear to be related to the complexity of the physical substratum, but was affected by biologically generated complexity. In contrast the settlement of barnacles was influenced by both habitat types. The distribution of mobile invertebrates in relation to topographic structures was highly variable; crevices therefore represented temporary habitats and refuges for these organisms. The shelter provided by both mussel beds and the physical properties of macroalgal canopy also influenced the distribution of such species. Results regarding species number and diversity on the concrete blocks were not consistent with the commonly held view that increased habitat complexity leads to increased richness and diversity. The movement patterns of intertidal predators were examined via the use of underwater camera technology. Biologically generated complexity was investigated in mussel beds in North Cornwall. Factorial manipulations of grazers and mussels were studied to examine their respective roles within a community. Predation and grazing pressure were influenced by both physical and biological structures. As a consequence the distribution of prey species were in part determined by the complexity of the habitat. Spatial and temporal scales of the structure and dynamics of mussel mosaics was also investigated. Habitat complexity was observed to have an impact on a number of community structuring processes. The generalities of these results and the requirements for future research are discussed throughout the thesis.</p

Factors affecting biodiversity on hermit crab shells

Article

Full-text available

Jun 2016
HYDROBIOLOGIA

This study explores the abundance, diversity and assemblage structure of epifauna on the shells used by two hermit crab species (Pagurus bernhardus and P. pubescens) in the Arctic (Svalbard and Northern Norway) and investigates the biotic and physical drivers of such patterns. Contrary to our expectations, we found that location (which reflects the variability in environmental conditions and the local species pool of potential colonizers) is a key determinant not only in the cold, ice-scoured, glacier-dominated Arctic shallows of Svalbard but also in boreal Norwegian fjords, where other factors were hypothesized to be more important. Depending on region, shell area and identity were of lesser magnitude, with larger and more irregular shells containing more diverse assemblages. Crab host species also played a role (P. pubescens-inhabited shells supported larger number of individuals and higher diversity than those of P. bernhardus) but this effect might be species or region specific. In this study, no effect of crab gender could be detected. The study indicated that epifaunal assemblages of hermit crab shells are influenced by complex set of factors that interact together to different degree at various locations.

Un manual de protocolos para evaluar la contaminación marina por efluentes domésticos.

Book

Full-text available

Jun 2013

Settlement-driven, multiscale demographic patterns of large benthic decapods in the Gulf of Maine

Article

Full-text available

Jan 1999

Three decapod species in the Gulf of Maine (American lobster Homarus americanus Milne Edwards, 1837, rock crab Cancer irroratus Say, 1817, and Jonah crab Cancer borealis Stimpson, 1859) were investigated to determine how their patterns of settlement and post-settlement abundance varied at different spatial and temporal scales. Spatial scales ranged from centimeters to hundreds of kilometers. Abundances of newly settled and older (sum of several cohorts) individuals were measured at different substrata, depths, sites within and among widely spaced regions, and along estuarine gradients. Temporal scales ranged from weekly censuses of new settlers within a season to inter-annual comparisons of settlement strengths. Over the scales considered here, only lobsters and rock crabs were consistently abundant in their early post-settlement stages. Compared to rock crabs, lobsters settled at lower densities but in specific habitats and over a narrower range of conditions. The abundance and distribution of older individuals of both species were, however, similar at all scales. This is consistent with previous observations that, by virtue of high fecundity, rock crabs have high rates of settlement, but do not discriminate among habitats, and suffer high levels of post-settlement mortality relative to lobsters. At settlement, large, habitat-scale differences exist for lobsters but not for rock crabs; these are probably the result of larval settling behavior. In contrast, patterns at the largest, interregional , spatial scales suggest oceanographic control of larval delivery. Increased mobility and vagility with greater body size for both species reduces demographic differences among older individuals over a range of spatial scales.

Influence of environmental variables over multiple spatial scales on the population structure of a key marine invertebrate

Article

Jul 2021
MAR ENVIRON RES

Quantifying scale-dependent patterns and linking ecological to environmental variation is required to understand mechanisms regulating biodiversity. We conducted a large-scale survey in rocky shores along the SE Brazilian coast to examine spatial variability in body size and density of an intertidal barnacle (Chthamalus bisinuatus) and its relationships with benthic and oceanographic predictors. Both the size and density of barnacles showed most variation at the smallest spatial scales. On average, barnacle body size was larger on shores located in areas characterised by higher chlorophyll levels, colder waters, low wave action and low influence of freshwater. Barnacles were more abundant at wave-exposed shores. We identified critical scales of spatial variation of an important species and linked population patterns to essential environmental predictors. Our results show that populations of this barnacle are coupled to scale-dependent oceanographic variation. This study offers insights into the mechanisms regulating coastal populations along a little studied coastline.

A Influência de Sistemas Frontais sobre as Assembleias Bentônicas de Pradarias de Fanerógamas Submersas Estuarinas

Thesis

Feb 2021

Dairana Misturini

The Influence of Occluded Fronts on the Benthic Assemblage of Estuarine Seagrass Meadows ----->>> The marine angiosperms meadows are habitats with a structuring and stabilizing role in estuarine substrates, which have strong ecological interactions with the benthic invertebrates. Disturbances caused by meteorological events, such as occluded fronts, which generate high rainfall, intense winds and soft bottom disturbance, can result in fluctuations in benthos density and diversity. Therefore, the aim of this research was to investigate the effects of occluded fronts on the sheltered and non-sheltered infauna and epifauna. Sampling was carried out at Saco do Justino, Patos Lagoon Estuary, immediately before and after the passage of four occluded fronts (March, May, August and November 2019) in three environments: Seagrass Meadow, Edge and Sandflat. In each environment and sampling, salinity and water temperature were measured; we determinet plant biomass (core 0.008 m²), canopy height and percentage of plant coverage (square 1 m²); samples of the benthic macrofauna (core 0.008 m²), sediments for granulometry and analysis of organic matter (core 0.002 m²) were collected. Meteorological data, flow, water temperature and salinity were obtained from databases. The seagrass meadow was multispecific in spring, summer and autumn (Potamogeton striatus, Ruppia maritima, Zannichellia palustris), with higher biomass in summer and lower in winter. During the sampling 13.828 macrozoobenthic organisms were taken. Sandflats benthic assemblage was distinct from the Seagrass Meadow. During the event one macrozoobenthic and sediments were not significantly affected by the occluded front, probably due to the greater structural complexity. In event two, there was a reduction in biomass and vegetal coverage, a worsening of sediment sorting in Edge and Sandflat and an increase in organic matter, leading to an increase in infauna density and diversity in Sandflat and Seagrass Meadow and a decrease in epifauna diversity in Seagrass Meadow. In event three, there was the highest benthic density and the lowest biomass of the seagrass, which may have influenced the reduction of infauna and epifauna densities, in all environments, after occluded front passage. In event four, the occluded fronts, in a scenario of greater water column depth and high river flow, may have resulted in an increase in infauna density and diversity. The passage of occluded fronts can affect positively (with increases) or negatively (with decreases) the epifaunal and infaunal assemblies density, diversity and evenness, however the greater structural complexity of seagrasses, shows their damping role by meteorological events.

Geology is a significant indicator of algal cover and invertebrate species composition on intertidal reefs of Ngari Capes Marine Park, south-western Australia

Article

Jan 2018

Effective management of rocky intertidal reefs requires an understanding of spatial variation in species composition and abundance, and the identification of high biodiversity areas. This study identified patterns of invertebrate biodiversity on intertidal reefs of differing underlying structure within Ngari Capes Marine Park, south-west Western Australia. Intertidal reef surveys were conducted at 12 limestone and 9 granite sites throughout the park. Geology was a significant indicator of variation in percentage cover of substrate and invertebrate composition, which covaried with rugosity and complexity. Limestone reefs were characterised by a combination of high and low branching algae and a sand-turf matrix, whereas granite reefs consisted of bare rock. A total of 15 772 individual invertebrates representing 10 phyla, 16 classes, 60 families and 121 species was recorded. A high abundance of dove (Family Columbellidae) and jewel top snails (Family Trochidae) characterised limestone reefs, whereas an assortment of limpets and chitons characterised granite reefs. Granite reefs contained more species (92 v. 63) and a higher mean (±s.d.) number of individuals (119 ± 58 v. 42 ± 79 m⁻²) than did limestone reefs. These findings emphasise the effect of underlying geology on the distribution of intertidal invertebrates and the need for management programs to accommodate different habitat types to effectively conserve biodiversity.

General spatial spectral variation in rocky intertidal communities from three biogeographical regions

Article

Full-text available

Jun 2017
J BIOGEOGR

Aim Understanding general spatial patterns of multiple species is a central aim of biogeography. Spatial analyses of coastal marine assemblages have shown an emergent pattern in that the variability in population abundances increases with increasing spatial scale of observation; i.e. a “red” spectrum of variation in population abundances. However, the generalization of these patterns to other ecological levels and across biogeographical regions remains unexplored. Here, we evaluate the consistency of a reddened relationship between the scale of observation and the variance in ecosystem properties in sessile intertidal rocky‐shore assemblages across three biogeographical regions. Location Replicate sites located in temperate (southern‐central Chile), sub‐Antarctic (Chilean South Patagonia) and Antarctic (West Antarctic Peninsula) regions. Methods A total of 16,225 photo‐quadrants were used to analyse local patterns of total community cover, bare substratum, total algal cover and total invertebrate cover. We used spectral analyses in which the spatial variance of each property was decomposed along a gradient of increasing distances between observations. Cross‐semivariograms were used to analyse the spatial covariation of dominant taxa. Results The analysed ecosystem properties showed a general reddened spectrum of variation that resembled patchy configurations of local communities. Additionally, cross‐semivariance analyses indicated mainly negative relationships of covariation between the abundances dominant sessile species at each site, suggesting a general trend of spatial asynchrony between competing species. Main conclusions To the best of our knowledge, this is the first study showing a general reddened pattern of spatial variation in relevant ecosystem‐level properties across the Pacific shore of South America, southern Patagonia and West Antarctic Peninsula. These patterns reflect the result of multiple biotic and abiotic processes that interact across spatial scales. In particular, we suggest that processes that generate spatial asynchrony between competing species, such as compensatory dynamics, are relevant to maintain the spatial structure of rocky‐shore communities.

Tidal Energy: The benthic effects of an operational tidal stream turbine

Article

Jun 2017

The effect of modified flow on epifaunal boulder reef communities adjacent to the SeaGen, the world's first grid-compliant tidal stream turbine, were assessed. The wake of the SeaGen was modelled and the outputs were used in conjunction with positional and substrate descriptor variables, to relate variation in epifaunal community structure to the modified physical environment. An Artificial Neural Network (ANN) and Generalised Linear Model (GLM) were used to make predictions on the distribution of Ecological Status (ES) of epifaunal communities in relation to the turbulent wake of the SeaGen. ES was assigned using the High Energy Hard Substrate (HEHS) index. ES was largely High throughout the survey area and it was not possible to make predictions on the spatial distribution of ES using an ANN or GLM. Spatial pattern in epifaunal community structure was detected when the study area was partitioned into three treatment areas: area D1; within one rotor diameter (16 m) of the centre of SeaGen, area D2; between one and three rotor diameters, and area D3; outside of three rotor diameters. Area D1 was found to be significantly more variable in terms of epifaunal community structure, bare rock distributions and ES than areas D2 and D3.

Recruitment Variability of Coral Reef Sessile Communities of the Far North Great Barrier Reef

Article

Full-text available

Apr 2016
PLOS ONE

One of the key components in assessing marine sessile organism demography is determining recruitment patterns to benthic habitats. An analysis of serially deployed recruitment tiles across depth (6 and 12 m), seasons (summer and winter) and space (meters to kilometres) was used to quantify recruitment assemblage structure (abundance and percent cover) of corals, sponges, ascidians, algae and other sessile organisms from the northern sector of the Great Barrier Reef (GBR). Polychaetes were most abundant on recruitment titles, reaching almost 50% of total recruitment, yet covered

Recruitment Variability of Coral Reef Sessile Communities of the Far North Great Barrier Reef

Article

Full-text available

Apr 2016
PLOS ONE

One of the key components in assessing marine sessile organism demography is determining recruitment patterns to benthic habitats. An analysis of serially deployed recruitment tiles across depth (6 and 12 m), seasons (summer and winter) and space (meters to kilometres) was used to quantify recruitment assemblage structure (abundance and percent cover) of corals, sponges, ascidians, algae and other sessile organisms from the northern sector of the Great Barrier Reef (GBR). Polychaetes were most abundant on recruitment titles, reaching almost 50% of total recruitment, yet covered <5% of each tile. In contrast, mean abundances of sponges, ascidians, algae, and bryozoans combined was generally less than 20% of total recruitment, with percentage cover ranging between 15–30% per tile. Coral recruitment was very low, with <1 recruit per tile identified. A hierarchal analysis of variation over a range of spatial and temporal scales showed significant spatio-temporal variation in recruitment patterns, but the highest variability occurred at the lowest spatial scale examined (1 m—among tiles). Temporal variability in recruitment of both numbers of taxa and percentage cover was also evident across both summer and winter. Recruitment across depth varied for some taxonomic groups like algae, sponges and ascidians, with greatest differences in summer. This study presents some of the first data on benthic recruitment within the northern GBR and provides a greater understanding of population ecology for coral reefs.

Living in clusters: The local spatial segregation of a lizard community

Article

Full-text available

Jan 2016

Plant and animal individuals can have a random, regular, or clustered distribution across space. The analyses of these patterns are important to understand how environment influences the spatial structure of species communities. We studied the local spatial segregation in a lizard community that is composed by four species in Salamanca (Spain). We inferred if habitat and / or competition are segregating factors. We collected a total of 675 records with a high‐accuracy GPS unit. We used Ripley’s K function to determine the distance threshold of clustering of the whole community and of each species separately, Delaunay’s triangulation (using as clustering distance threshold the Nearest Neighbor Index) to identify spatial species’ clusters, and an overlapping analysis (using buffers around species records), as well as a distance comparison analysis (among intra‐species and inter‐species distances), to measure the species’ spatial segregation. The lizard community was distributed in 34 clusters, with 13 composed by only one species and 21 composed by two or more species. Our results indicated that species of the same genus segregated almost totally, inhabiting different habitats; on the other hand, species of different genera presented partial segregation, sharing some habitats. Ground‐dwelling species had partial spatial segregation as they compete for similar habitats. Saxicolous species presented a high degree of spatial segregation due to their different habitat. © 2016, Asociacion Herpetologica Espanola. All rights reserved.

Rocky Intertidal Invertebrates. The Potential for Metapopulations within and among Shores

Article

Jan 2006

Mark P. Johnson

The role of rocky intertidal is reflected in spatial ecology, for which a variety of metapopulation models have been explicitly or implicitly examined on rocky shores. Metapopulation biology and intertidal ecology share an appreciation of dispersal as a key theme. Indeed, larval ecology is central to population and community studies in marine ecology. Although metapopulation models help define the potential dynamics of a system, spatially extensive fine-scale data are required to determine the relevant scales of processes and to discriminate between competing hypotheses. In the case of rocky shore invertebrates, this information does not yet seem to be available for any species. Although a metapopulation structure may be appropriate, many populations may be approximated by simpler approaches. Metapopulation biology could help predict over what scales trophic links will be most strongly emphasized, including the different potential responses of systems to episodic events at different scales. Beyond the challenges in defining the spatial structure of populations across different scales, there are two areas where metapopulation ecology may be particularly relevant to rocky intertidal invertebrates. First, there is relatively good evidence that some species are structured as within-shore populations. Second, intertidal invertebrate species vary greatly in life history characteristics.

Do marine and terrestrial ecologists do it differently?

Article

Dec 2005

Do artificial vs natural substrates cause a difference in assemblages of peracarids? A case study in the Western Mediterranean basin

Article

Full-text available

Jul 2023

The aim of this investigation was to assess the differences in terms of α-diversity, species composition and trophic structure between peracarid assemblages inhabiting artificial hard substrates and those present on natural ones at two sites in the Western Mediterranean Sea. In each one, samples were collected from natural and artificial substrates, and the extracted peracarids were identified to the species level. Each sample was characterised by its Total Abundance, Species Richness, and 1-D Simpson, Shannon, Margalef and Equitability indices. A cluster plot based on the Bray-Curtis coefficient was conducted to detect the presence of distinct assemblages. In addition, the proportion of individuals belonging to each feeding guild was studied. The ecological indices revealed that assemblages from the artificial substrates at the Villaricos site showed lower values of diversity, while they were more diverse at the Calpe site. These results indicated that artificial hard substrates were not always inadequate ground for these animals. The species composition differed between artificial and natural hard substrates in the two studied sites and the trophic structure was also modified, although, in this case, the changes were similar in both sites. However, the difference in both respects seems to be higher between sites than between substrates, evidencing the importance of local scale processes.

Spatial distribution patterns of striped venus clam (Chamelea gallina, L. 1758) natural beds in the Gulf of Cádiz (SW Spain): Influence of environmental variables and management considerations

Article

Full-text available

Jun 2023

Spatial distribution of characteristic population parameters (density, biomass and mean size) of Chamelea gallina were analyzed from systematic survey data applying a geostatistical approach in the Gulf of Cádiz (SW Spain). The influence of static (depth and distance to inland outflows), dynamic (sediment and water column features) environmental variables on density, biomass and mean size was also investigated. The global estimations of kriged density mean was 8.30 ind m −2 , biomass mean was 23.78 g m −2 , and mean size was 18.71 mm, with the species heterogeneously distributed along the whole sandy subtidal strip of the coast of Huelva. The resulting kriged map shows the location and extension of the patches (5 NM range) in the study area; where the highest density and biomass hot-spots were observed near the river mouths, except for the Guadiana River. This species was present from 3 to 16 m, but preferred the depth window between 6-8 m, having a density and biomass peak at approximately 7 m depth. A negative and significant correlation was found between density/biomass and the coefficient of variation of mean size suggesting a density-dependent process. The most influential factors on density and biomass were depth, sediment characteristics (grain size and percentage of organic content), distance from river mouths and waste water treatment plants, and sea bottom temperature. This study, in addition to reporting on the current status of these natural beds and the influence of dynamic and static environmental variables on their distribution, proposes an additional approach to estimating several biological parameters in C. gallina that could be valuable for the spatial management of this commercial resource and highlight the role of marine protected areas.

Species composition, distribution, and zonation patterns in the intertidal seaweed assemblages from Santo Antão, Cape Verde

Article

Full-text available

May 2023

Intertidal communities have been extensively studied for decades. Many of these studies have focused on macroalgae, as they are key components of many rocky coastal ecosystems. Despite this, there are still regions of the world where there is a lack of knowledge of intertidal macroalgal communities. This is the case in some tropical regions, such as the Cape Verde archipelago, located on the tropical west coast of Africa. To contribute to the knowledge of the macroalgal communities of this region, during July 2022, we studied the distributional pattern and zonation of macroalgal communities along the rocky intertidal of Santo Antão Island, the northernmost island of the archipelago and the least studied. Using a nested design, we compared the macroalgal assemblages of six rocky shores along the entire coastline, including three sites per shore, and four quadrats per site and tidal level. We found 43 macroalgal species – 29 Rhodophyta, 12 Ochrophyta, 2 Chlorophyta – and one Cyanobacteria. The orders Ceramiales, Corallinales, and Gigartinales were the groups more represented, followed by Ectocarpales and Dictyotales. The upper intertidal was dominated by brown algae, while red algae dominated the middle intertidal. Green algae had a scarce presence in both tidal levels. Our results found no differences between the north and south of the island but between rocky shores and tidal levels. Our results provide for the first time comprehensive information on the seaweed community structure, zonation patterns, and a comparison of seaweed abundances in a vertical and horizontal gradient along the entire rocky shores of Santo Antão Island. In the face of the current climate change, our data can be the baseline for future work on algal communities in this region.

Checklist, diversity descriptors and selected descriptions of a highly diverse intertidal sponge (Porifera) assemblage at Costa do Descobrimento (Bahia, Brazil)

Article

May 2023

Costa do Descobrimento is located in southern Bahia, Brazil, and only 22 species of sponges (Porifera) were known from the area until now, despite its important reef formations. In the present study, we report a checklist of the sponges of Costa do Descobrimento and their distribution in the studied reefs, with several species illustrated in life. We also describe nine new sponge records for this region, some of which are new records for Brazil, or new records of species previously only poorly known. We present alpha and beta diversity indices and compare the sponge assemblage of the sampled locations. Four reefs were considered: two fringing reefs (Arraial D’Ajuda—AA and Coroa Vermelha / Mutá—CVM) and two offshore Municipal Marine Park “Parque Municipal Marinho— (P.M.M. Coroa Alta—CA and P.M.M. Recife de Fora—RF). A total of 229 specimens were collected (224 Demospongiae, 2 Homoscleromorpha and 3 Calcarea). These were classified in 101 morphotypes. Studied materials included representatives of 15 orders, 34 families and 48 genera. The richest orders are Haplosclerida (29 spp.), Poecilosclerida (15 spp.) and Tetractinellida (11 spp.). The richest families were Chalinidae (24 spp.), Clionaidae (7 spp.) and Mycalidae and Suberitidae (6 spp. each). The richest genus is, by far, Haliclona (20 spp.). Only 13 species were shared among all four reefs surveyed, namely Amphimedon viridis, Cinachyrella alloclada, C. apion, Cladocroce caelum, Cliona varians, Dysidea robusta, Mycale (Naviculina) diversisigmata, Niphates erecta, Spirastrella hartmani, Tedania (Tedania) ignis, Terpios fugax, Tethya bitylastra and T. maza. The reefs with the highest richness were CA and CVM, and the lowest richness was observed in RF. The most similar reefs in terms of species composition were CA and CVM, while AA and RF were more dissimilar to the previous reefs, but also from each other. While the difference among CA, CVM and AA was mainly explained by species turnover, RF differed from the previous based on its lower richness (nestedness component). Even though CA and CVM were the richest reefs, AA presented the highest number of exclusive species, highlighting the uniqueness of this reef, and urging the inclusion of local beachrock fringing reefs in a more holistic conservation strategy at Costa do Descobrimento.

Could the annual Saccorhiza polyschides replace a sympatric perennial kelp (Laminaria ochroleuca) when it comes to supporting the holdfast-associated fauna?

Article

Full-text available

Oct 2022
MAR ENVIRON RES

Kelp forests dominate temperate rocky shores worldwide but are declining globally with consequences for organisms that depend on them. In NW Iberia, the golden kelp (Laminaria ochroleuca) commonly occurs alongside a fast-growing annual that, unlike the golden kelp, does not seem to have receded in recent times (Saccorhiza polyschides). Here, we assessed whether the bulbous holdfast of S. polyschides could replace the intricate holdfast of L. ochroleuca as epifaunal habitat provider. Richness, diversity and total abundance of epifauna was similar in both seaweeds, while colonial/encrusting fauna was more abundant in L. ochroleuca. More importantly, each host supported a distinctive assemblage structure, indicating that S. polyschides seems an unsuitable replacement for L. ochroleuca as habitat provider for holdfast epifauna. Therefore, while S. polyschides may contribute substantially to the kelp forest canopy in some seasons, a regional decline of L. ochroleuca will likely alter the patterns of biodiversity within kelp stands.

Structure of the bivalve (Mollusca) assemblage of Mazatlan bay, Mexico, and its relationship to environmental variables

Article

Full-text available

Sep 2022

This work describes the structure of the assemblage of bivalve mollusks (i.e., composition, abundance, density, distribution and species diversity) of four representative rocky beaches of Mazatlan bay, Mexico. Biological samples were taken in the upper intertidal, lower intertidal and shallow subtidal of the beaches together with environmental parameters: type of sediment, organic matter, water temperature, dissolved oxygen, wave exposure and concentration of chlorophyll a. A total of 19,848 individuals distributed in 77 species, 50 genera and 27 families were recorded. The permutational ANOVA and PERMANOVA indicated significant differences in the bivalve assemblage structure among environments across studied sites. However, the intertidal (IT) and SS environments had different bivalve assemblages. Six species had a broad distribution: Acar rostae, Arcopsis solida, Isognomon janus, Saccostrea palmula Chama buddiana and Carditamera affinis. Four species had the highest density in the IT: Brachidontes semilaevis (196.0 ind m2), B. adamsianus (35.0 ind m2), Arcopsis solida (18.0 ind m2) and Lithophaga aristata (15.0 ind m2), and in the SS were Lithophaga aristata (7.1 ind m2), B. semilaevis and Acar rostae (3.2 ind m2). This study shows that exposure to waves was determinant for the bivalve distribution that inhabit the intertidal zone. In contrast, chlorophyll a and organic material are the variables that best explain the distribution of the species in the SS. However, more detailed information is required regarding the importance of the interaction between the hydrodynamics and the topography of the rocky beaches of Mazatlan bay.

Weak effects of age but important role of microhabitats in community differences between breakwaters and natural rocky shores across a latitudinal gradient

Article

Full-text available

Aug 2022
GLOBAL ECOL BIOGEOGR

Aim Coastal infrastructures are increasing at different latitudes, and their deployment often results in a complete replacement of natural habitats. Although infrastructure provides novel habitats, ecological engineering can increase their similarity to natural rocky habitats. One hurdle for effective design of greener infrastructure is the scarce information on the processes that underpin differences in the structure of communities between built and natural habitats. Using long‐term data of intertidal community structure, we tested whether the magnitude of between‐habitat differences changes with breakwater age and across latitudes, and we examined the role of topographic microhabitats (i.e., rock pools) in driving these differences. Location Nine locations distributed from 18 to 41°S. Time period 2016–2020. Methods We sampled the mid‐intertidal community structure on breakwaters of different age and on natural rocky habitats (platforms and boulder fields) and assessed the availability of microhabitats, such as crevices and rock pools, along a coastline spanning 23° of latitude. Using generalized additive models (GAMs), we assessed the effect of the different factors on species diversity and functional group abundances. Results Age since construction was a poor predictor of differences between breakwaters and natural habitats. Communities on older breakwaters bore a poor resemblance to the species composition or functional group abundances found in natural habitats. The magnitude of differences between breakwaters and natural habitats varied with latitude, with season and with the type of natural habitat attributable to differences in microhabitats, especially in rock pool availability. Conclusions Our results indicate that replacement of rocky habitats with breakwaters will cause permanent alterations to coastal ecosystems. Our findings suggest that the availability of microhabitats able to shelter species from stressful environmental conditions is more important at lower and intermediate latitudes; hence, they should be incorporated primarily into infrastructures in tropical or subtropical areas. These strategies could help to compensate for the impacts on rocky ecosystems associated with increases in coastal urbanization.

Impacto por Petróleo em Repovoamento de Costões rochosos

Experiment Findings

Full-text available

Feb 2003

Oil terminals is a potential source of oil contamination due to load operations and discharge of the oil ships. Recently significant accidents come happening. In Rio de Janeiro, the main accidents happened in the Guanabara Bay in January of 2000 and in the Ilha Grande Bay in May and September of 2002. The exposure to the oil can result in alterations in every community affecting directly the ecological succession and the recolonization on rocky shore. In this study an experiment was made in field, using two rocky shores with similar fauna and flora composition, in the Ilha Grande Bay with the objective to evaluate the recolonization of a rocky shore submitted to a simulated oil spill. They were researched four bands of vertical distribution of the organisms, the first and upper, dominated by Chthamalus bisinuatus; the medium bands, dominated by Tetraclita stalactifera and vermertidae and the lower band dominated by macroalgae, using quadrat of 100 cm2 for upper band and of 400 cm2 for the medium and lower bands in 5 replies for monthly accompaniment of the recolonization. Each quadrat, in both rocky shores, it was totally cleared before the contact with the oil. The rocky shore artificially impacted was involved by contention barriers and 20L of oil crude (ligth rarabian) were spilled inside. The recolonization of the rocky shores was observed during the following ten months. The obtained results showed for an interference of the light arabian oil in the recolonization of the intertidal communities in the upper bands, mainly in the first 15 days after the contact with the oil. The process of recolonization of the gastropods of the upper bands probably more affected by the oil. The results of the populations of the gastropod Littorina ziczac indicated a non recovery of this organism in the impacted rocky shore, it was only appeared in the ninth month. The oil used in the simulation didn't probably interfere in the colonization of the band 3 for the mollusk Isognomon bicolor, invasion specie with high competitive success. The studied bands demonstrated different times of recolonization, in agreement with each population of organisms.

Variabilidad espacial de ensambles bentónicos intermareales en Bahía Yendegaia, Canal Beagle, ecorregión subantártica de Magallanes.

Article

Full-text available

Dec 2021

La ecorregión subantártica de Magallanes posee una heterogénea costa de fiordos y canales, con una gran extensión de ecosistemas intermareales sujetos al efecto de condiciones climáticas extremas características de zonas de altas latitudes. Trabajos de investigación recientes sugieren que la estructura de los ensambles intermareales que habitan en ambientes extremos, como subantárticos y antárticos, presenta altas variaciones horizontales y verticales que se acentúan a escalas espaciales finas. Éste podría ser un patrón general en hábitats intermareales de altas latitudes del hemisferio sur, y en este trabajo evaluamos la hipótesis que la variabilidad horizontal y vertical de los ensambles bentónicos intermareales en ambientes extremos subantárticos es mayor a escalas finas. En marzo-abril de 2017 se analizó la variabilidad espacial sobre los ensambles bentónicos intermareales de bahía Yendegaia, Reserva de la Biosfera Cabo de Hornos, como modelo de estudio con un diseño anidado con diferentes escalas espaciales que van desde centímetros a kilómetros. El análisis de los componentes de varianza y pseudo-varianza mostró una significativa variación horizontal y vertical a escalas finas. Se identificaron seis comunidades con una marcada zonación vertical. Las especies más representativas fueron el molusco Perumytilus purpuratus y las algas Porphyra/Pyropia sp1. y Ulva flexuosa, las que tuvieron una alta variación vertical en escalas finas. Estos patrones apoyan la hipótesis testeada, sin embargo, es probable que factores físicos locales del hábitat relacionados con cambios abióticos también influyan significativamente sobre las variaciones espaciales a pequeñas escalas en las comunidades de bahía Yendegaia. Por lo tanto, se propone extender este tipo de investigaciones incorporando la variabilidad temporal y datos ambientales en bruto. Estos estudios permitirán detectar los factores locales más influyentes sobre la variación espacial de los ensambles bentónicos intermareales subantárticos.

Relaciones Biogeográficas Insulares de Littorina keenae Rosewater, 1978,

Article

Full-text available

Jul 2021

A morphometric analysis of the rocky intertidal gastropod Littorina keenae Rosewater, 1978, from Guadalupe and Cedros Islands, in the Mexican Pacific was performed. The analysis considered the distance among six shell points with which four phenetic parameters were obtained. Principal Component Analysis (PCA) and Empirical Orthogonal Function Analysis (EOF) were developed. The Canonical correlation showed three groups homogeneous with each other but differed from each other. These dissimilarities probably reflect the synergistic effect of island environmental variables such as temperature, swell, the intertidal zone's slope, and the California Current influence. The PCA showed sensitivity to differentiate, at an ecological level, among populations of the same species; Furthermore, with the creation of the EOFs, it is shown that the differences among the groups probably have an explanation at the phylogenetic level; however, more studies are needed. The use of distances among points on the shell, as a database, and the description of the traditional phenetic characters, is an objective approach because of the bias produced in the sizes caused by organisms' age differences. Based on this study's results, the use of distances and distance ratios among points of the littorinid shell is proposed as a complementary approach to classical taxonomy and community ecology.

Insular Biogeographic Relationships of Littorina keenae Rosewater, 1978, from Isla Guadalupe and Isla Cedros in the Mexican Pacific, a morphometric analysis Relaciones Biogeográficas Insulares de Littorina keenae Rosewater, 1978, de Isla Guadalupe e Isla Cedros en el Pacífico Mexicano, un análisis morfométrico

Article

Full-text available

Apr 2021

Insular Biogeographic Relationships of Littorina keenae Rosewater, 1978, from Isla Guadalupe and Isla Cedros in the Mexican Pacific, a morphometric analysis

Article

Full-text available

Jun 2021

Alfredo Ortiz Sartorius

Coastal Resources Exploitation can Mask Bottom–up Mesoscale Regulation of Intertidal Populations

Article

Full-text available

Jul 2006
HYDROBIOLOGIA

We describe the spatial distribution patterns of rocky intertidal Patella spp. limpets (heavily collected by shellfishers) and top-shell snails belonging to the genus Osilinus (comparatively slightly harvested) through a multiscaled sampling design spanning five orders of magnitude of spatial variability (from 10s of m to 100s of km) throughout the Canarian Archipelago (eastern Atlantic); where rocky intertidal assemblages on opposite sides of the Archipelago (western vs. eastern islands) are subjected to different regimes of bottom-up effects, as large spatial variation in oceanographic conditions is recorded across an east–west gradient. We tested the hypothesis that the response of rocky intertidal populations to mesoscale oceanographic bottom-up variability (quantified using differences in Chlorophyll-a concentration among islands as an approximation to bottom-up effects) depends on the exploitation status of coastal resources, by means of a correlative approach. Our study represent another case in which mesoscale shore-associated physical processes seem to be correlated to large-scale differences (variability among islands, 10s to 100s of km apart) in the abundance of slightly harvested intertidal grazers (topshell snails). In contrast, we did not observe large-scale spatial differences for heavily collected grazers (limpets). In conclusion, our study suggests that the signal of bottom-up processes in coastal populations may be difficult to demonstrate under intense human exploitation.

Environmental Stress Tolerance and Antioxidant Response of Palisada perforata (Rhodophyta) from a Tropical Reef 1

Article

Feb 2021

In this study, we analyzed the antioxidant activity and total phenolic content of the intertidal seaweed Palisada perforata collected from different reef microhabitats (sheltered site, tide pool, plateau, and exposed site) along the coast of Pernambuco (Brazil). Both parameters were compared with the same parameters of this species grown in the laboratory under two experiments simulating temperature, salinity and desiccation conditions found in the reef. After both experiments (temperature x salinity and desiccation), the algal photosynthetic performance was measured through chlorophyll fluorescence parameters using a pulse‐amplitude modulation fluorometer to test their stress response. Palisada perforata likely underwent stress by desiccation due to tidal fluctuations rather than to temperature or salinity changes. This conclusion agrees with our observations of the plateau site´s specimens, which were exposed to both air and UV radiation during low tides and exhibited higher antioxidant activity to avoid oxidative damage. However, despite the environmental stress, the antioxidant activity remained low, suggesting that photoinhibition is a crucial protection mechanism against oxidative damage.

Effect of fishing pressure on the spatio-temporal variability of the parrotfish, Sparisoma cretense (Pisces: Scaridae), across the Canarian Archipelago (eastern Atlantic)

Article

Jan 2006
FISH RES

We investigated spatio-temporal variability in the population structure of the parrotfish, Sparisoma cretense (Linnaeus, 1758), throughout the Canarian Archipelago (eastern Atlantic Ocean) with underwater visual transects. By means of a multiscaled hierarchical sampling design spanning three orders of magnitude of spatial variability (from 10 s of meters between replicated 100 m 2 transects to 100 s of kilometres among islands) and four sampling times (twice a year in 2003 and 2004); we related differences between islands to differences in the degree of fishing pressure. The mean abundance of parrotfish across all counts was 6.79 ± 0.46 ind 100 m −2 (mean ± S.E., n = 768 transects), while the mean biomass was 593.81 ± 45.61 g 100 m −2 (mean ± S.E., n = 768). Abundances and biomasses of S. cretense clearly differed between islands, although they were relatively consistent between the sampling times. The different abundances and biomasses observed between islands were correlated with fishing pressure, providing evidence that fishing was responsible for the inter-island differences. Differences in the size-structure between the eastern and western islands suggest differences in the recruitment periodicity at both groups of islands, which could be related to large-scale spatial variation in the oceanographic conditions across an east-west gradient along the Canary Islands.

Environmental heterogeneity mediates scale- dependent declines in kelp diversity on intertidal rocky shores

Article

Full-text available

Mar 2019
PLOS ONE

Biodiversity loss is driven by interacting factors operating at different spatial scales. Yet, there remains uncertainty as to how fine-scale environmental conditions mediate biological responses to broad-scale stressors. We surveyed intertidal rocky shore kelp beds situated across a local gradient of wave action and evaluated changes in kelp diversity and abundance after more than two decades of broad scale stressors, most notably the 2013-2016 heat wave. Across all sites, species were less abundant on average in 2017 and 2018 than during 1993-1995 but changes in kelp diversity were dependent on wave exposure, with wave exposed habitats remaining stable and wave sheltered habitats experiencing near complete losses of kelp diversity. In this way, wave exposed sites have acted as refugia, maintaining regional kelp diversity despite widespread local declines. Fucoids, seagrasses and two stress-tolerant kelp species (Saccharina sessilis, Egregia menziesii) did not decline as observed in other kelps, and the invasive species Sargassum muticum increased significantly at wave sheltered sites. Long-term monitoring data from a centrally-located moderate site suggest that kelp communities were negatively impacted by the recent heatwave which may have driven observed losses throughout the region. Wave-sheltered shores, which saw the largest declines, are a very common habitat type in the Northeast Pacific and may be especially sensitive to losses in kelp diversity and abundance, with potential consequences for coastal productivity. Our findings highlight the importance of fine-scale environmental heterogeneity in mediating biological responses and demonstrate how incorporating differences between habitat patches can be essential to capturing scale-dependent biodiversity loss across the landscape.

ESTRUCTURA DEL ENSAMBLAJE DE BIVALVOS Y SU RELACIÓN CON VARIABLES AMBIENTALES DE LA BAHÍA DE MAZATLÁN, MÉXICO

Conference Paper

Full-text available

Oct 2017

María del Carmen Esqueda-González

Los bivalvos marinos frecuentemente llegan a ser el grupo dominante de los fondos blandos, y constituyen la clase más abundante y de mayor riqueza de especies dentro de los moluscos después de los gasterópodos. A partir de muestreos realizados en diciembre 2008 y marzo, junio y agosto 2009, en el intermareal superior (IS), intermareal inferior (II) y submareal somero (SS) de cuatro sitios representativos de la bahía de Mazatlán, México, se describe la estructura del ensamblaje de los bivalvos (composición, abundancia, densidad, distribución y diversidad de especies). Además, se analiza la relación de la composición y de la abundancia con las siguientes variables ambientales: tipo de sedimento, materia orgánica, temperatura del agua, oxígeno disuelto, exposición al oleaje y concentración de clorofila a. Se recolectaron 19,848 individuos, distribuidos en 77 especies, 50 géneros y 27 familias. Los análisis ANOVAs y PERMANOVAs indicaron que no existen diferencias significativas (p>0.05) entre los ambientes IS–II, de esta forma, sólo se consideraron dos ambientes: intermareal (IM) y SS. La mayor riqueza de especies se registró en el IM de las playas rocosas Olas Altas y Los Pinos, y en el SS de la Casa del Marino e isla Venados. Las distribuciones de Acar rostae, Arcopsis solida, Isognomon janus, Saccostrea palmula, Chama buddiana y Carditamera affinis fueron las más amplias, ya que estuvieron en los dos ambientes de todos los sitios. Cuatro especies obtuvieron la mayor densidad en IM: Brachidontes semilaevis (196.0 ind/m2), B. adamsianus (35.0 ind/m2), A. solida (18.0 ind/m2) y Lithophaga aristata (15.0 ind/m2), y tres en SS: L. aristata (7.1 ind/m2), A. rostae y B. semilaevis (3.2 ind/m2). La exposición al oleaje fue determinante para la distribución de los bivalvos que habitan en el intermareal rocoso y, en el SS, la clorofila a y la materia orgánica son las variables que mejor explican la distribución de especies en este ambiente.

Spatial analysis of bivalve mollusks diversity in Mazatlan Bay, Mexico

Article

Apr 2017

Mazatlan Bay is considered the northern boundary of the region with the greatest species richness of infaunal and epifaunal bivalve mollusks in the tropical eastern Pacific. The present study aimed to quantify changes in the patterns of bivalve species diversity in Mazatlan Bay at different spatial scales and to determine which scale contributes more towards the species turnover of the total diversity in the Bay. Additive and multiplicative partitions were performed in the α, β and γ diversities of four sites and two environments (intertidal and shallow subtidal) within the Bay. A total of 19,848 individuals from 27 families and 77 species of bivalves were recorded. The effectiveness of the sampling effort was evaluated using species accumulation curves, which revealed a representation of 73% in the four sites and two environments. Rarity was characterized by 20% of the singleton and unique species, and 9% of the doubletons and duplicate species. Additive partitioning showed that the species turnover among sites and between environments contributed more to bivalve total diversity. In multiplicative partitions of the sites in both environments, the greatest species richness was found at the lower scales (α1). The sites and environments showed a clear decrease in the abundant (N1) and very abundant species (N2) from α to β1–β2 scales. The spatial variability of the different habitats of the bay is important to maintain the high species richness and high percentage of different life forms found in the Bay. The β1 and β2-diversities constitute the most important component for supporting the bivalve total diversity (γ) of Mazatlan Bay.

Consistent patterns of spatial variability between NE Atlantic and Mediterranean rocky shores

Article

Full-text available

Nov 2016

Examining how variability in population abundance and distribution is allotted among different spatial scales can inform of processes that are likely to generate that variability. Results of studies dealing with scale issues in marine benthic communities suggest that variability is concentrated at small spatial scales (from tens of centimetres to few metres) and that spatial patterns of variation are consistent across ecosystems characterized by contrasting physical and biotic conditions, but this has not been formally tested. Here we quantified the variability in the distribution of intertidal rocky shore communities at a range of spatial scales, from tens of centimetres to thousands of kilometres, both in the NE Atlantic and the Mediterranean, and tested whether the observed patterns differed between the two basins. We focused on canopy-forming macroalgae and associated understorey assemblages in the low intertidal, and on the distribution of Patella limpets at mid intertidal levels. Our results highlight that patterns of spatial variation, at each scale investigated, were consistent between the Atlantic and the Mediterranean, suggesting that similar ecological processes operate in these regions. In contrast with former studies, variability in canopy cover, species richness and limpet abundance was equally distributed among spatial scales, possibly reflecting the fingerprint of multiple processes. Variability in community structure of low intertidal assemblages, instead, peaked at the largest scale, suggesting that oceanographic processes and climatic gradients may be important. We conclude that formal comparisons of variability across scales nested in contrasting systems are needed, before any generalization on patterns and processes can be made.

Assesing Edge-Effects in Posidonia oceanica seagrass meadows: A multidisciplinary approach

Thesis

Full-text available

Sep 2016

Jon Lapeyra Martin

Structural boundaries in ecosystems play an important role both in the context of seascape architecture and ecological processes. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is considered an ecosystem engineer species, forming habitats of great ecological value and providing many ecosystem services. However so far, only few studies have addressed the importance of edges on this habitat. Therefore, this study aims to (1) determine whether there are differences between seagrass-sand corridors edges and the adjacent continuous meadow, and (2) investigate whether anthropogenic pressures can cause disturbances in the measured parameters along the edges and the meadow. To reach those objectives, we have developed a multidisciplinary approach combining plant physiology, canopy community studies and seagrass structural parameters characterization. Two sites located ca. 15 m depth with contrasted natural and anthropogenic influences were selected in Calvi Bay (Corsica, France). At each site two natural occurring edges-sand corridors (SC) were examined. We performed in situ chlorophyll fluorescence measurements using a Pulse Amplitude Modulated (Diving-PAM) fluorometry in order to assess the photosynthetic rate of the shoots. Vagile-macrofauna of the leaf stratum was sampled by a hand-towed net, and the major taxonomic groups were sorted, counted, and identified. Meadow’s biometric measurements and the epiphytic biomass were also determined. Regarding edge-meadow matrix, results have shown highest differences on matrix structural parameters such as shoot density and shoot type proportions. Shoot density was found to decrease in edges considerably. We found c.a to 60 % plagiotropic shoots on edges while in continuous meadow orthotropics were predominant (up to 90 %). Vagile-fauna population densities and diversity did not differ significantly among stations studied, neither by sites. Photosynthetic rate and leaf surface values also did not show changes between edges and continuous meadow. However, results did show that plagiotropic shoots had higher photosynthetic rate than orthotropics, and also that epiphyte abundance sorted out to be much higher (up to 54 %) on edges. The overall results showed that edges differ from continuous meadow especially referring to habitat architectural parameters; nevertheless ecological effects regarding anthropogenic impacts are far from being well understood. We concluded that particular attention must be given to these edge areas for the purpose of developing and enhancing seagrass management and conservation strategies.

Spatial pattern of distribution of marine invertebrates within a subtidal community: Do communities vary more among patches or plots?

Article

Full-text available

Sep 2016

Making links between ecological processes and the scales at which they operate is an enduring challenge of community ecology. Our understanding of ecological communities cannot advance if we do not distinguish larger scale processes from smaller ones. Variability at small spatial scales can be important because it carries information about biological interactions, which cannot be explained by environmental heterogeneity alone. Marine fouling communities are shaped by both the supply of larvae and competition for resources among colonizers—these two processes operate on distinctly different scales. Here, we demonstrate how fouling community structure varies with spatial scale in a temperate Australian environment, and we identify the spatial scale that captures the most variability. Community structure was quantified with both univariate (species richness and diversity) and multivariate (similarity in species composition) indices. Variation in community structure was unevenly distributed between the spatial scales that we examined. While variation in community structure within patch was usually greater than among patch, variation among patch was always significant. Opportunistic taxa that rely heavily on rapid colonization of free space spread more evenly among patches during early succession. In contrast, taxa that are strong adult competitors but slow colonizers spread more evenly among patches only during late succession. Our findings show significant patchiness can develop in a habitat showing no systematic environmental spatial variation, and this patchiness can be mediated through different biological factors at different spatial scales.

Identifying relevant scales of variability for monitoring epifaunal reef communities at a tidal energy extraction site

Article

Feb 2017

The SeaGen tidal energy turbine is located in the Strangford Narrows, Northern Ireland. The Narrows are designated as a Natura 2000 site, host unique biological assemblages and exhibit very high tidal velocities. This study describes an asymmetrical BACI design monitoring program that was aimed at assessing the potential impact the SeaGen may have on epifaunal boulder reef communities. This study presents a novel methodology for monitoring epifaunal communities within highly variable and poorly understood tidal rapid environments. We identify bare rock as a key measure of disturbance within tidal energy extraction sites and propose a new successional model for epifaunal reef communities on subtidal stable substrates. We also present an Ecological Quality Ratio (EQR); the High Energy Hard Substrate (HEHS) index for use in monitoring programs within tidal energy extraction sites. Seasonality significantly affected epifaunal community structure, bare rock distributions and EQR values at all stations equally over time. SeaGen is not significantly affecting epifaunal community structure, bare rock distributions or EQR values at the impact site. The HEHS index has the potential to standardise benthic monitoring in tidal energy extraction sites.

Macrobenthos of the coastal Budi Lagoon, Southern Chile: Changes associated with seasonal environmental variation

Article

Full-text available

Oct 2016

The purpose of the present study was to investigate the seasonal relationship of macrobenthos richness and abundance with sediment characteristics (i.e. texture and organic material) for the coastal Budi Lagoon in southern Chile. Physicochemical measurements and macrobenthos samples were taken over the course of a year at nine sampling stations. Sandy-muddy sediment was the most common, and high percentages of organic material were registered, varying significantly between seasons and stations. The recorded organic material was related to natural (resident wild birds) and anthropogenic (agriculture) sources. Regarding fauna, 28 benthonic taxa and 7092 individuals were identified, with temporal and spatial variations. The most abundant taxa year-round were the molluscs Littoridina cumingii and Kingiella chilenica and the bristle worm Prionospio patagonica. Together, the obtained results evidence the important impact of organic material on the macrobenthos, with macrobenthic richness and abundance decreasing in conditions of high organic material content. The recorded variations for different taxa may indicate a response to the land use around the Budi Lagoon, which is intensely subjected to agricultural and tourist activities.

Alpha and beta diversity of freshwater meiofauna at different spatial scales in a Neotropical lotic system

Article

Jan 2016

Meiofaunal assemblages are important components of benthic communities in freshwater habitats, but studies about their ecology are scarce. In the present study we investigated the spatial and temporal distribution patterns of freshwater meiofaunal taxa, in a lotic system in southeastern Brazil, assessing a and b diversities through additive partitioning of diversity. At each of six sampling sites, a 50-m transect was divided into five equal sections. Two random samples were collected in each section. Local spatial scales (a and b 1) and among areas (b 3) made the highest contribution to overall richness, but seasonal variation could be seen. Non-randomness patterns were observed, especially at the lowest and highest spatial scales, showing the effects of local intraspecific aggregation and environmental variability among areas. Temporal scale analysis showed that diversity was highly aggregated at the monthly scale, but sampling location affected these results. Community composition results highlighted the contrasting conditions found at the sampling sites, highlighting b 3 as an important component of g diversity across spatial scales. The effects of different levels of environmental degradation and precipitation on community composition and meiofaunal abundance affected the ability of the community to recover and recolonise the meiobenthos.

Spatial distribution of small benthic invertebrates in rocky upper infralittoral at the Asinara Island (NW Mediterranean): A pilot study

Article

Dec 2004
VIE MILIEU

A pilot study was carried out in the Asinara Island National Park (NW Mediterranean) at Giordano Bay to investigate the spatial variation in abundance of small invertebrates inhabiting upper infralittoral hard bottoms covered by algae. Six experimental areas were randomly chosen within a mixed assemblage of erect algae at the bay. Samples of benthic fauna were collected by cutting through the algae to the rock surface with open-ended plastic cylinders of 40, 60 and 80 mm in diameter (small, medium and large size, respectively). The abundance of the most common taxa, for both macrofaunal and meiofaunal components, was found unaffected by the size of the sampling unit, suggesting that the distribution of organisms is spatially heterogeneous and that the average distance among aggregation of benthic assemblages is larger than the sampling unit sizes considered. Further, taxonomic resolution used is discussed as a possible cause for the results obtained. Cost-benefit analyses have determined the optimal allocation of resources to use in future sampling of small benthic invertebrates at the site.

Thraustochytrids (fungoid protists): An unexplored component of marine sediment microbiota

Article

Full-text available

Apr 2004

Thraustochytrids are poorly known fungoid protists able to decompose refractory organic substrates such as cellulose. These microorganisms probably play an important role in the microbial loop of marine sediments. This paper reports a study conducted on thraustochytrids dwelling in a sandy shore of the Eastern Ligurian Sea. One hundred twenty eight samples (1 ml each) were collected, to examine Thraustochytrid spatial distribution, following a nested ANOVA design, that incorporated 3 successively smaller spatial scales (different sampling units ranging from metres to centimetres). Samples were examined by a direct, improved, fluorochrome-count method also suitable for ciliates. Sampling was repeated 4 times in autumn-winter. The average abundance of thraustochytrids (±SE) was 42.3±2.9 ml-1, with no significant decrease over time. The densities of thraustochytrids and ciliates varied significantly but at different spatial scales: the former between squares (3.3 × 3.3 m), and the latter between subplots (0.01 × 0.01 m), indicating their tendency to form patches at different spatial scales. A significant correlation was found between the densities of the two protists, suggesting some interaction between them could occur. The thraustochytrid abundance supports the idea that these protists play a an important role in carbon cycling of Mediterranean sandy shores.

Under the radar: Sessile epifaunal invertebrates in the seagrass Posidonia australis

Article

Aug 2015

Despite the current global decline in seagrass, sessile epifaunal invertebrates inhabiting seagrass ecosystems, particularly sponges and ascidians, have been poorly studied due to their taxonomic complexity. Understanding patterns of distribution of sessile epifaunal communities in seagrass meadows is an important precursor to determining the processes driving their distribution and species interactions. This study (1) identified the sponge and ascidian assemblage associated with Posidonia australis meadows and (2) determined distributional patterns of these invertebrates at a hierarchy of spatial scales in Jervis Bay, Australia. We used a fully nested design with transects distributed in the seagrass (10s m apart), two sites (100s m apart), and six locations (km apart). Within these transects, we recorded the abundance, volume, diversity and substratum used for attachment by sponges and ascidians. We encountered 20 sponge species and eight ascidian species; they were sporadically distributed in the seagrass meadows with high variability among the transects, sites and locations. A few sponge and ascidian species dominated the assemblage and were widespread across the largest spatial scale sampled. The remaining species were mostly rare and sparsely distributed. Sponges attached to a variety of substrata but most notably shells, P. australis and polychaete tubes. No obligate seagrass species were recorded although three species predominantly used P. australis as a substratum. These sponge species relying heavily on seagrass for their attachment are likely prone to disturbances impacting their host habitat. Examining the response of sessile epifauna to the degradation of their seagrass habitat remains a key challenge for the future.

Patchiness in American lobster benthic recruitment at a hierarchy of spatial scales

Article

Full-text available

Oct 2015

The overarching goal of ecology is to uncover natural patterns and the processes that underlie them. Importantly, both patterns and processes are dependent on scale. In this study, we assessed spatial patterns in benthic recruitment (density of young-of-year within a few months post-settlement) of American lobster in the Canadian Gulf of Maine by deploying, over 3 consecutive years, between 413–505 cobble-filled collectors on structurally complex cobble bottom in a spatially nested design: regions (127 and 674 km2), areas within regions (0.4–4 km2), sites within areas (0.003–0.23 km2), and “sub-sites” within sites (0.00004–0.06 km2). We quantified spatial patterns of benthic recruitment using a repeated-measures nested ANOVA, variance component analysis and a randomization approach developed for this study. These analyses indicated that the area scale (0.4–4 km2) was most important to patchiness in benthic recruitment, with a significant but smaller amount of variation in recruitment at the region scale (127 and 674 km2), and virtually no significant variation at the smaller spatial scales. Despite interannual variability in benthic recruitment, these spatial patterns and scales of patchiness were largely consistent across years. Of the 11 study areas surveyed, 3 were identified as recruitment “hotspots” and 4 as recruitment “coldspots”, based on density frequency distributions. The location of these different recruitment “hotspots” and “coldspots” suggests that patchiness at the area scale may be related to the effect of local currents and topographical features on larval retention. The lack of significant patchiness at the smallest scale of the collector is at first surprising, given previous work on substrate selection by competent post-larvae, but likely arose because our sampling tool offered a standard and high-quality substrate, indirectly confirming the importance of substrate to small-scale patterns of benthic recruitment.

Tide, time and space: Scales of variation and influences on structuring and sampling beach clams

Article

Jan 2016
J EXP MAR BIOL ECOL

Charles A Gray

Calcinai et al 2015

Data

Sep 2015

Preliminary study of the population and reproductive dynamics of Echinaster sepositus (Spinulosida: Echinasteridae) in Cala del Racó

Article

Full-text available

Mar 2024

Introduction: The red starfish (Echinaster sepositus) is one of the most common asteroid species in the Mediterranean Sea. However, information about their biology or their role in benthic communities is scarce. Objective: This study aims to provide new information on the ecology of this species through the temporal characterization of the population of E. sepositus in Cala del Racó (Alicante, Spain) and the in situ monitoring of its reproductive cycle. Methods: For this purpose, three study areas were established at different depths. For each of the recorded starfish, data about the size, the substrate on which it was found, the area, the depth and the sex in the case of observing the reproduction were collected. Results: A total of 19 samplings have been carried out throughout a year of study. In this way, it has been possible to observe that the density of individuals increases in the shallower zone during autumn and winter, when the temperature drops to 14.13 ºC, while it decreases in spring and summer when the temperature rises to 27.17 ºC. Those results are reversed in the deepest part of the study. The highest density of individuals (0.51 ind/m²) occurred in October. Arborescent photophilic algae and crustose coralline algae were the substrates with the highest number of E. sepositus recorded. Medium to large specimens are located preferably on crustose coralline algae or arborescent photophilic algae, while smaller individuals were mostly located on Posidonia oceanica. No specimens of E. sepositus were observed spawning. Conclusions: Data leads to assume that there is a migration of starfishes towards more superficial areas when the water is at colder temperature and towards deeper areas when the temperature increases. It is valued the possibility that there is a change in the nutritional needs of E. sepositus throughout its development. According to our observations, the future reproduction studies should be concentrated between late-summer and early-autumn.

Substratos artificiais na avaliação da diversidade de macroinvertebrados bentónicos

Thesis

Full-text available

Apr 2019

Regina Neto

As macroalgas são organismos dominantes e abundantes que atuam como um substrato estrutural biológico com impactos positivos na sobrevivência, riqueza e abundância das espécies locais. Através da sua estrutura física, estas espécies modificam as condições físicas do habitat e influenciam direta e indiretamente as interações biológicas, desempenhando assim um papel importante na estruturação das comunidades macrobentónicas. No entanto, estes habitats são difíceis de amostrar devido ao facto de serem substratos estruturalmente complexos, pelo que a utilização de substratos artificiais se torna uma alternativa válida. A vantagem deste tipo de metodologia é a utilização duma unidade padronizada para comparações quantitativas de amostras separadas espacialmente, bem como elimina a necessidade duma amostragem destrutiva dos substratos naturais. Foram colocados dois substratos artificiais diferentes em ambiente entre marés na Torpedera (2 metros) e subtidal na Enseñada de San Cristovo (9 metros) durante um período de 3 meses (maio a agosto). Em relação às métricas utilizadas, os índices de riqueza, abundância, diversidade e equitabilidade mostraram diferenças significativas entre os substratos colocados na Torpedera, enquanto que na Enseñada de San Cristovo só houve diferenças a nível da abundância de organismos. Na Torpedera o substrato AS2MS contêm mais espécies e menos indivíduos, enquanto que na Enseñada de San Cristovo ocorre o oposto. Em ambiente intertidal, a exposição às correntes e fluxo de água levou ao provisionamento de um maior nicho para organismos filtradores e construtores de casulo no substrato AS1-T e maior assentamento de partículas e sedimentos no substrato AS2-T permitindo um maior número de detritívoros. A profundidades maiores houve preferência de certas espécies pelo substrato AS2-SC devido ao aumento dos espaços intersticiais, o que permite a presença de organismos de maiores dimensões. Os padrões de abundância e riqueza de macroinvertebrados sugerem que as preferências de habitat podem estar relacionadas com diferentes modos de alimentação, estratégias reprodutivas, morfologias e mobilidade, além de confirmarem a dependência de vários grupos de organismos para com a arquitetura do habitat e a sua importância na estruturação das comunidades macrobentónicas, bem como a capacidade dos substratos artificiais suportarem comunidades diversificadas.

Interhemispheric comparison of scale-dependent spatial variation in the structure of intertidal rocky-shore communities

Article

Full-text available

Jun 2020

In rocky intertidal habitats, the pronounced increase in environmental stress with elevation, caused by tides, generates significant vertical variation in community structure. Along coastlines, environmental changes generate horizontal biological variation, which, when measured at large sampling intervals, generally surpasses vertical biological variation. It is unknown, however, how vertical biological variation compares with horizontal biological variation when the latter is measured in environmentally similar habitats. We tested the hypothesis that, for sites experiencing similar environmental conditions along the shore, horizontal biological variation does not surpass vertical biological variation even when horizontal variation is measured at large sampling intervals along the coast. We compared vertical and horizontal variation in intertidal communities by surveying habitats experiencing the same wave exposure on the NW Atlantic and SE Pacific coasts. We measured biological variation based on differences in species richness, occurrence, and abundance between quadrats from low and high elevations (vertical variation) and between quadrats at three horizontal scales of sampling interval on both coasts: local (tens of cm between quadrats), meso- (ca. 100 km between quadrats), and regional (ca. 200 km between quadrats). We measured biological variation for all species combined, separately for sessile and mobile species, and for the numerically dominant species. The data analyses indicated that horizontal biological variation was never higher than vertical biological variation, not even at the regional scale, providing support for our hypothesis. Overall, our findings suggest that studies comparing spatial scales of biological variation should consider the underlying environmental variation in addition to simply scale alone.

Predominant east to west colonizations across major oceanic barriers: Insights into the phylogeographic history of the hydroid superfamily Plumularioidea, suggested by a mitochondrial DNA barcoding marker

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Full-text available

Oct 2019

We provide preliminary insights into the global phylogeographic and evolutionary patterns across species of the hydrozoan superfamily Plumularioidea (Cnidaria: Hydrozoa). We analyzed 1,114 16S sequences of 198 putative species of Plumularioidea collected worldwide. We investigated genetic connections and divergence in relation to present‐day and ancient biogeographic barriers, climate changes and oceanic circulation. Geographical distributions of most species are generally more constrained than previously assumed. Some species able to raft are dispersed widely. Human‐mediated dispersal explains some wide geographical ranges. Trans‐Atlantic genetic connections are presently unlikely for most of the tropical‐temperate species, but were probably more frequent until the Miocene–Pliocene transition, before restriction of the Tethys Sea and the Central American Seaway. Trans‐Atlantic colonizations were predominantly directed westwards through (sub)tropical waters. The Azores were colonized multiple times and through different routes, mainly from the east Atlantic, at least since the Pliocene. Extant geminate clades separated by the Isthmus of Panama have predominantly Atlantic origin. Various ancient colonizations mainly directed from the Indian Ocean to the Atlantic occurred through the Tethys Sea and around South Africa in periods of lower intensity of the Benguela upwelling. Thermal tolerance, population sizes, dispersal strategies, oceanic currents, substrate preference, and land barriers are important factors for dispersal and speciation of marine hydroids.

Polychaete assemblages in a tropical hypersaline coastal lagoon of the southeastern Gulf of Mexico during the rainy season

Article

Full-text available

Aug 2019

Introduction: The Río Lagartos lagoon, located in the Ría Lagartos Biosphere Reserve, Yucatán, Gulf of Mexico, is a coastal hypersaline system ca. 80 km long (east-west). It comprises three basins: western (close to Río Lagartos fishermen village), middle (Las Coloradas) and eastern (close to El Cuyo fishermen village), that communicate through very narrow natural channels. Despite several studies have been performed on the vertebrate fauna, the aquatic invertebrates, and especially polychaetes, remain largely unknown. Objective: The objective of this study is to describe the composition and distribution of the benthic polychaete community, and to analyse potential environmental drivers. Methods: The biological material was collected in 16 stations distributed along the lagoon during the rainy season (September 2017). Two replicates per station were obtained using a Ponar standard dredge or cores (6” diameter). Environmental variables such as grain size, organic carbon content in the sediments, and salinity, among others, were measured. Results: A total of 827 specimens belonging to 26 species and 16 families were identified. Of these, 23 species are new records for the Río Lagartos lagoon. Community composition changed between the different basins associated with strong gradients in salinity, subaquatic vegetation (algae and seagrasses) proportions in the samples and grain size. No polychaetes were recorded at the easternmost basin (El Cuyo basin), where salinity was between 67-80 psu. In the rest of the lagoon, the distribution of polychaetes was heterogeneous, especially near the mouth (western basin), where the highest and lowest density, species richness and diversity were recorded. The highest density was found at station 6, where dense algal mats of the genus Avrainvillea dominated. The families Syllidae and Nereididae were the most abundant and widely distributed families in the lagoon. The species Syllis lagunae and Nereis pelagica dominated the western basin and Prionospio heterobranchia and Sphaerosyllis taylori dominated the middle basin. Conclusions: The salinity records associated with some species were well above the top limits previously reported, establishing the euryhaline character of many species in the region.

Scales of spatial patterns of distribution of intertidal snails

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Awards for Distinguished Professional Contributions: Lester Luborsky.