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Sylvain Doledec - One of the best experts on this subject based on the ideXlab platform.
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integration of invertebrate Traits into predictive models for indirect assessment of stream functional integrity a case study in portugal
Ecological Indicators, 2012Co-Authors: Maria Joao Feio, Sylvain DoledecAbstract:Abstract Biological Traits are increasingly used for describing ecological functioning of stream benthic assemblages. Such approaches associate information on species distribution to their Biological characteristics (e.g. life history, physiology, dispersal ability) providing a Biological Trait profile of communities. They may complement structural bioassessment measures using taxonomic composition by providing indirect information on stream ecological functioning, with the additional advantage of being less constrained by biogeographic differences. A multivariate predictive model, that provides a site-specific list of expected taxa at least disturbed conditions was recently developed for the bioassessment of Portuguese streams. Here, we tested if the inclusion of Trait information in the model would also enable the detection of most common anthropogenic disturbances (i.e., organic contamination, hydrological disturbance) and provide diagnostic hints for causal relationships. We used existing information on 11 invertebrate Biological Traits and their 54 categories to convert the observed and expected taxonomic composition at several test sites into expected and observed Trait compositions. The first three axes of a normalised PCA (Principal Components Analysis) performed on disturbance variables accounted for 42.7% of explained variability. The proportion of variance in disturbance explained by the three types of Trait-based metrics (overall observed/expected Trait composition, Trait-category profile difference and Traits profile dissimilarity) ranged between 9% and 32%. Our predictions made on the response of observed to expected Trait categories for organic contamination were generally confirmed and demonstrated that disturbances resulted in a change in those Traits conferring species resilience capacity and sensitivity to oxygen depletion, as well as a shift in the proportion of animals with filter-feeding behaviour. Variations in observed to expected Trait-category differences showed that even a small increase in organic contamination led to a significant change in the Biological Trait profile, as expected. By contrast, only two out of 11 Trait category predictions were confirmed for hydrological disturbance. Finally, we found that 4/11 and 9/11 observed to expected Trait differences showed a significant deviation with organic contamination and hydrological disturbance, respectively, whereas all 11 observed to expected Trait differences responded to overall disturbance. These changes in Trait profiles reflect changes in the performance of invertebrate communities to cope with disturbance, which potentially can alter ecosystem functioning (e.g., energy flow or chemical cycling). In conclusion, the integration of Biological Trait information in an AUSRIVAS type predictive model allowed the detection of a general disturbance gradient and particularly organic contamination, which indicates their value in addition to taxonomic-based assessment.
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Invertebrate community responses to land use at a broad spatial scale: Trait and taxonomic measures compared in New Zealand rivers
Freshwater Biology, 2011Co-Authors: Sylvain Doledec, Ngaire Philipps, Colin TownsendAbstract:1. Large-scale comparative studies of ecological responses to anthropological stressors in rivers require measures that are consistent across a range of spatial scales. The Biological Trait profile of communities offers an alternative approach to traditional measures of macroinvertebrate taxonomic identity and is less constrained by biogeographic influences. 2. We compared the capacities of taxonomic composition and Biological Trait composition to discriminate the effects of land use (measured as percentage of the catchment in pasture) across a large geographic zone (the whole of New Zealand) in 30 sub-catchments grouped into five ecoregions throughout the North and South Islands of New Zealand. In addition, we investigated Trait consistency (i.e. whether similar Traits had similar Trait responses to land use at local (catchment) and broad scales). 3. The analysis of taxonomic composition showed that community structure was indeed influenced by land-use intensity, but that relationships differed among ecoregions. In contrast, traditional assessment metrics (Macroinvertebrate Community Index, richness in Ephemeroptera, Plecoptera and Trichoptera taxa) and Trait composition were uninfluenced by region. Trait responses were consistent at the broad and catchment scales, with similar Traits responding to pastoral land use at both scales. 4. We used general linear modelling to investigate individual Trait responses to land-use intensity, catchment area and region, focussing on 15 Trait categories known to be influenced by land-use intensity at the catchment scale. Several Trait categories varied with land-use intensity and demonstrated consistency at both catchment and broad scales. Of these, the representation of shorter generation time, asexual reproduction and hermaphroditism, ability to lay eggs beneath the water surface, egg protection and respiration types tolerant of oxygen depletion generally increased in assemblages exposed to more intense pastoral land use. At the same time, the representation of short life duration of adults, prevalence of laying eggs at the water surface, sexual reproduction and low body flexibility decreased in assemblages exposed to land-use intensification.
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taxonomic and Biological Trait differences of stream macroinvertebrate communities between mediterranean and temperate regions implications for future climatic scenarios
Global Change Biology, 2007Co-Authors: Nuria Bonada, Sylvain Doledec, Bernhard StatznerAbstract:Streams in mediterranean regions have highly seasonal discharge patterns, with predictable torrential floods and severe droughts. In contrast, discharge is less variable in temperate regions and intermittent flow conditions are uncommon. Hydroclimatic models predict that climate change would increase frequency and severity of floods and droughts across Europe, thus increasing the proportion of streams with mediterranean characteristics in actually temperate areas. Correspondingly, understanding actual ecological differences between mediterranean and temperate streams may help to anticipate large-scale ecological impacts of climate change. Given that large-scale factors determine local community composition, we hypothesized that climatic differences between mediterranean and temperate regions should affect the taxonomic and Biological Trait composition in streams. We assembled the abundance of stream macroinvertebrate genera of 265 sites each from the Mediterranean Basin and from temperate Europe and linked these abundances to published information on 61 categories of 11 Biological Traits reflecting the potential of resilience from and resistance to disturbances. Although regional taxonomic richness was higher in the mediterranean than in the temperate region, local taxonomic richness and diversity did not significantly differ between regions. Local Trait richness and diversity were significantly higher in the mediterranean region. Both local taxonomic and Traitcommunity composition differed between regions, but the former varied much more than the latter, highlighting that climate change could produce large changes in the taxonomic but rather weak changes in the Trait composition. The mediterranean region was characterized by macroinvertebrates with higher dispersion and colonization capabilities, suggesting that species loss in the temperate region, by extinction or northward emigration of taxa, would be compensated for by immigration of southern mediterranean taxa. Thus, climate change would likely have stronger implications for the local conservation of taxa than for the Trait composition of stream macroinvertebrate communities.
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conservation of taxonomic and Biological Trait diversity of european stream macroinvertebrate communities a case for a collective public database
Biodiversity and Conservation, 2007Co-Authors: Bernhard Statzner, Nuria Bonada, Sylvain DoledecAbstract:The use of databases for the conservation of biodiversity is increasing. During the last decade, such a database has been created for European stream macroinvertebrates. Today, it includes 527 sites that are the least human-impacted representatives of many stream types across many European regions. It includes data on the abundance of 312 invertebrate genera, several environmental site characteristics, collection methods, bibliographic data sources, and 11 Biological Traits of the genera (e.g. size, life cycle, food and feeding habits, described in 61 categories). The database will be useful in addressing many topics that are potentially relevant to biodiversity conservation. To illustrate this potential, we provide examples of how the data could be exploited. First, we describe the frequency of some taxonomic and Biological characteristics (e.g. richness and diversity of genera and Traits) of the macroinvertebrate communities and assess how these characteristics are related (e.g. how Trait richness increases with genus richness). Second, we describe the frequency of some characteristics of the genera and Traits (e.g. occurrence frequency, abundance, dispersion index) and again assess how these characteristics are related (e.g. how occurrence increases with abundance). Finally, we suggest how the database could be developed into a collective, publicly accessible database that covers stream types and regions of Europe more comprehensively.
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Biological Trait composition of european stream invertebrate communities assessing the effects of various Trait filter types
Ecography, 2004Co-Authors: Bernhard Statzner, Sylvain Doledec, Bernard HuguenyAbstract:Understanding the action of filters on the Biological Trait composition of communities is constrained by the multitude of filter types (e.g. abiotic vs biotic, actual vs historical) that may cause changes of a multitude of Traits (e.g. small vs large body size, short vs long life cycle) at a multitude of spatial scales (e.g. continent vs landscape vs local site). Using published data on the as natural as possible abundances and 11 Biological Traits (described through 63 categories) of 254 European stream invertebrate genera, we assessed how already available knowledge can serve to identify the importance of the action of different types of Trait filters at two spatial scales. Therefore, we analysed observed and simulated abundance-weighted Trait compositions at the local scale of 384 running water sites (RWS) and at the landscape scale of 14 large biogeographical regions (LER). Actual abiotic filters acted significantly and independently of the taxonomic richness on the invertebrate Traits at the RWS- and LER-scale, whereas biotic filters had no significant effect. Evidence for the action of historical Trait filters across Europe was only weak at both scales. Size, reproductive cycle, respiration and locomotion technique, feeding habits and vulnerability to disturbance responded to altitude and stream width of the RWS according to existing views about the effects of riparian, physiological, interstitial or disturbance controls of these Traits. These controls acted independently on Trait categories that did not co-occur within the genera, because correlations of size categories with other Trait categories were higher in the abundance-weighted Trait array (across communities) than in the original Trait array (across genera). Overall, many of the 63 Trait categories were scarcely affected by the Trait filters considered in this study. Therefore, we briefly discuss potential effects of continental filters and of stream system-specific, local physical filters, as the latter should produce similar Trait patterns on a global scale. Our study suggests that analyses of the currently available knowledge can simplify the complicated hypothetical framework on Trait filter actions, which sharpens the focus on future research needs.
Stefan G Bolam - One of the best experts on this subject based on the ideXlab platform.
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Assessing cumulative human activities, pressures, and impacts on North Sea benthic habitats using a Biological Traits approach
ICES Journal of Marine Science, 2017Co-Authors: Andrew Kenny, Stefan G Bolam, Chris Jenkins, Daniel Wood, Peter Mitchell, Callum Scougal, Adrian JuddAbstract:Abstract The application of a Biological Traits analysis, in the present study, has allowed benthic habitat sensitivities and their risk of impact to be mapped at a spatial scale appropriate for the assessment of the North Sea ecoregion. This study considered habitat impacts associated with five important marine sectors; bottom fishing, marine aggregate dredging, sediment disposal, renewable energy devices (tidal, waves, and wind) and the oil and gas sectors, both individually and cumulatively. The significance of the “actual” footprint of impact arising from these human activities and their associated pressures (sediment abrasion, sediment removal, smothering, and placement of hard structures) is presented and discussed. Notable differences in sensitivity to activities are seen depending on habitat type. Some of the more substantial changes in benthic habitat function evaluated are potentially associated with the placement of hard structures in shallow mobile sedimentary habitats, which result in a shift in habitat dominated by small, short-living infaunal species, to a habitat dominated by larger, longer-lived, sessile epibenthic suspension feeders. In contrast, the impacts of bottom fishing, dredging and disposal activities are all assessed to be most severe when executed in deep, sedimentary habitats. Such assessments are important in supporting policies (e.g. spatial planning) directed towards ensuring sustainable “blue-growth,” through a better understanding of the potential ecological impacts associated with human activities operating across different habitat types. The aim of this study is to provide a better understanding of the spatial extent of selected human activities and their impacts on seabed habitats using a Biological Trait-based sensitivity analysis.
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towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem
Ices Journal of Marine Science, 2016Co-Authors: Adriaan D. Rijnsdorp, Stefan G Bolam, Aleksandar Ivanovic, Jan Geert Hiddink, Lene Buhlmortensen, Katell G. Hamon, Ole Ritzau Eigaard, Francois Bastardie, Niels T Hintzen, Andrew KennyAbstract:A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales provides indicators for both trawling pressure and ecological impact. It builds on high-resolution maps of trawling intensity and considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the framework, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of Biological Traits are chosen to determine either the vulnerability of the benthos to the impact of that gear component, or to provide a proxy for their ecological role. The approach considers gear elements, such as otter boards, twin trawl clump, and groundrope, and sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a Biological-Trait approach that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics, dispersal), and their ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the Sublittoral mud (EUNIS A5.3) is affected the most due to the combined effect of intensive fishing and large proportions of long-lived taxa
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Fishing Sea-bed Habitat Risk Assessment (A framework towards the quantitative assessment of trawling impact on the sea-bed and benthic ecosystem)
2015Co-Authors: Adriaan D. Rijnsdorp, Stefan G Bolam, Jan Geert Hiddink, Katell G. Hamon, Ole Ritzau Eigaard, Francois Bastardie, Niels T Hintzen, Ana Ivanovic, Lene Buhl-mortensen, Andrew KennyAbstract:A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales considers the physical effects of trawl gears on the seabed, on marine taxa and the functioning of the benthic ecosystem. A reductionist approach is applied that breaks down a fishing gear in its components and distinguishes a number of Biological Traits that are chosen to determine the vulnerability of benthos for the impact of a gear component or to provide a proxy for their ecological role. The approach considers a wide variety of gear elements, such as otter boards, twin trawl clump and ground-rope, and, sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilisation and penetration, are a function of the mass, size and speed of the individual component. The impact of the elements on the benthic community are quantified using a Biological-Trait approach, that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics) and the ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the sublittoral mud habitat is impacted most due to the combined effect of an intensive fishing and high proportions of long-lived taxa.
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macrofaunal recovery following the intertidal recharge of dredged material a comparison of structural and functional approaches
Marine Environmental Research, 2014Co-Authors: Stefan G BolamAbstract:Abstract There is a growing need to understand the functional implications of anthropogenic pressures, such as those following coastal disposal of dredged material. Current assessments, based on taxonomic structure of benthic organisms, only provide a limited capacity to determine functional impacts or recovery. This study assesses recovery of two intertidal dredged material recharge schemes, comparing results obtained based on taxonomic structure (univariate and multivariate approaches) and function (Biological Trait composition, functional diversity, secondary production) of the benthic assemblages. The assemblages recolonising both schemes were consistently less speciose, less densely-populated and exhibited multivariate community structures that differed from those of the reference areas. However, for both schemes metrics of functionality converged to those of reference areas, although some differences in Trait composition persisted for up to 3 years. These data support the proposition that impacts of, and recovery from, anthropogenic disturbance should be assessed using a combination of both functional and taxonomic structural approaches.
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sensitivity of macrobenthic secondary production to trawling in the english sector of the greater north sea a Biological Trait approach
Journal of Sea Research, 2014Co-Authors: Stefan G Bolam, Roger Coggan, J D Eggleton, Markus Diesing, David StephensAbstract:Abstract Demersal trawling constitutes the most significant human impact on both the structure and functioning of coastal seabed fauna. While a number of studies have assessed the impacts of trawling on faunal community structure and the degree to which different taxa are vulnerable to trawling, few have focused on how these impacts affect important ecological functions of the seabed. In this study, we use Biological Trait analysis (BTA) to assess the relative sensitivity of benthic macrofauna to trawling, in both the short- and long-term, and use this information to describe the spatial variation in sensitivity of secondary production for the Greater North Sea (GNS). Within the GNS, estimates of total production varied by almost three orders of magnitude, from 1.66 kJ m− 2 y− 1 to 968.9 kJ m− 2 y− 1. Large-scale patterns were observed in the proportion of secondary production derived from trawling-sensitive taxa. In the southern North Sea, total production is predominantly governed by taxa with low sensitivity to trawling, whereas production is relatively trawling-sensitive in the northern North Sea and western English Channel. In general, the more sensitive and productive regions are associated with poorly-sorted, gravelly or muddy sediments, while the less sensitive and less productive regions are associated with well-sorted, sandy substrates. These relationships between production sensitivity and environmental features are primarily due to variations in long-term recovery; total production of most assemblages is highly sensitive to the direct impacts of trawling. We discuss the implications of these findings for management 1decisions to improve the environmental sustainability of trawling.
Bernhard Statzner - One of the best experts on this subject based on the ideXlab platform.
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taxonomic and Biological Trait differences of stream macroinvertebrate communities between mediterranean and temperate regions implications for future climatic scenarios
Global Change Biology, 2007Co-Authors: Nuria Bonada, Sylvain Doledec, Bernhard StatznerAbstract:Streams in mediterranean regions have highly seasonal discharge patterns, with predictable torrential floods and severe droughts. In contrast, discharge is less variable in temperate regions and intermittent flow conditions are uncommon. Hydroclimatic models predict that climate change would increase frequency and severity of floods and droughts across Europe, thus increasing the proportion of streams with mediterranean characteristics in actually temperate areas. Correspondingly, understanding actual ecological differences between mediterranean and temperate streams may help to anticipate large-scale ecological impacts of climate change. Given that large-scale factors determine local community composition, we hypothesized that climatic differences between mediterranean and temperate regions should affect the taxonomic and Biological Trait composition in streams. We assembled the abundance of stream macroinvertebrate genera of 265 sites each from the Mediterranean Basin and from temperate Europe and linked these abundances to published information on 61 categories of 11 Biological Traits reflecting the potential of resilience from and resistance to disturbances. Although regional taxonomic richness was higher in the mediterranean than in the temperate region, local taxonomic richness and diversity did not significantly differ between regions. Local Trait richness and diversity were significantly higher in the mediterranean region. Both local taxonomic and Traitcommunity composition differed between regions, but the former varied much more than the latter, highlighting that climate change could produce large changes in the taxonomic but rather weak changes in the Trait composition. The mediterranean region was characterized by macroinvertebrates with higher dispersion and colonization capabilities, suggesting that species loss in the temperate region, by extinction or northward emigration of taxa, would be compensated for by immigration of southern mediterranean taxa. Thus, climate change would likely have stronger implications for the local conservation of taxa than for the Trait composition of stream macroinvertebrate communities.
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conservation of taxonomic and Biological Trait diversity of european stream macroinvertebrate communities a case for a collective public database
Biodiversity and Conservation, 2007Co-Authors: Bernhard Statzner, Nuria Bonada, Sylvain DoledecAbstract:The use of databases for the conservation of biodiversity is increasing. During the last decade, such a database has been created for European stream macroinvertebrates. Today, it includes 527 sites that are the least human-impacted representatives of many stream types across many European regions. It includes data on the abundance of 312 invertebrate genera, several environmental site characteristics, collection methods, bibliographic data sources, and 11 Biological Traits of the genera (e.g. size, life cycle, food and feeding habits, described in 61 categories). The database will be useful in addressing many topics that are potentially relevant to biodiversity conservation. To illustrate this potential, we provide examples of how the data could be exploited. First, we describe the frequency of some taxonomic and Biological characteristics (e.g. richness and diversity of genera and Traits) of the macroinvertebrate communities and assess how these characteristics are related (e.g. how Trait richness increases with genus richness). Second, we describe the frequency of some characteristics of the genera and Traits (e.g. occurrence frequency, abundance, dispersion index) and again assess how these characteristics are related (e.g. how occurrence increases with abundance). Finally, we suggest how the database could be developed into a collective, publicly accessible database that covers stream types and regions of Europe more comprehensively.
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Biological Trait composition of european stream invertebrate communities assessing the effects of various Trait filter types
Ecography, 2004Co-Authors: Bernhard Statzner, Sylvain Doledec, Bernard HuguenyAbstract:Understanding the action of filters on the Biological Trait composition of communities is constrained by the multitude of filter types (e.g. abiotic vs biotic, actual vs historical) that may cause changes of a multitude of Traits (e.g. small vs large body size, short vs long life cycle) at a multitude of spatial scales (e.g. continent vs landscape vs local site). Using published data on the as natural as possible abundances and 11 Biological Traits (described through 63 categories) of 254 European stream invertebrate genera, we assessed how already available knowledge can serve to identify the importance of the action of different types of Trait filters at two spatial scales. Therefore, we analysed observed and simulated abundance-weighted Trait compositions at the local scale of 384 running water sites (RWS) and at the landscape scale of 14 large biogeographical regions (LER). Actual abiotic filters acted significantly and independently of the taxonomic richness on the invertebrate Traits at the RWS- and LER-scale, whereas biotic filters had no significant effect. Evidence for the action of historical Trait filters across Europe was only weak at both scales. Size, reproductive cycle, respiration and locomotion technique, feeding habits and vulnerability to disturbance responded to altitude and stream width of the RWS according to existing views about the effects of riparian, physiological, interstitial or disturbance controls of these Traits. These controls acted independently on Trait categories that did not co-occur within the genera, because correlations of size categories with other Trait categories were higher in the abundance-weighted Trait array (across communities) than in the original Trait array (across genera). Overall, many of the 63 Trait categories were scarcely affected by the Trait filters considered in this study. Therefore, we briefly discuss potential effects of continental filters and of stream system-specific, local physical filters, as the latter should produce similar Trait patterns on a global scale. Our study suggests that analyses of the currently available knowledge can simplify the complicated hypothetical framework on Trait filter actions, which sharpens the focus on future research needs.
Andrew Kenny - One of the best experts on this subject based on the ideXlab platform.
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Assessing cumulative human activities, pressures, and impacts on North Sea benthic habitats using a Biological Traits approach
ICES Journal of Marine Science, 2017Co-Authors: Andrew Kenny, Stefan G Bolam, Chris Jenkins, Daniel Wood, Peter Mitchell, Callum Scougal, Adrian JuddAbstract:Abstract The application of a Biological Traits analysis, in the present study, has allowed benthic habitat sensitivities and their risk of impact to be mapped at a spatial scale appropriate for the assessment of the North Sea ecoregion. This study considered habitat impacts associated with five important marine sectors; bottom fishing, marine aggregate dredging, sediment disposal, renewable energy devices (tidal, waves, and wind) and the oil and gas sectors, both individually and cumulatively. The significance of the “actual” footprint of impact arising from these human activities and their associated pressures (sediment abrasion, sediment removal, smothering, and placement of hard structures) is presented and discussed. Notable differences in sensitivity to activities are seen depending on habitat type. Some of the more substantial changes in benthic habitat function evaluated are potentially associated with the placement of hard structures in shallow mobile sedimentary habitats, which result in a shift in habitat dominated by small, short-living infaunal species, to a habitat dominated by larger, longer-lived, sessile epibenthic suspension feeders. In contrast, the impacts of bottom fishing, dredging and disposal activities are all assessed to be most severe when executed in deep, sedimentary habitats. Such assessments are important in supporting policies (e.g. spatial planning) directed towards ensuring sustainable “blue-growth,” through a better understanding of the potential ecological impacts associated with human activities operating across different habitat types. The aim of this study is to provide a better understanding of the spatial extent of selected human activities and their impacts on seabed habitats using a Biological Trait-based sensitivity analysis.
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towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem
Ices Journal of Marine Science, 2016Co-Authors: Adriaan D. Rijnsdorp, Stefan G Bolam, Aleksandar Ivanovic, Jan Geert Hiddink, Lene Buhlmortensen, Katell G. Hamon, Ole Ritzau Eigaard, Francois Bastardie, Niels T Hintzen, Andrew KennyAbstract:A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales provides indicators for both trawling pressure and ecological impact. It builds on high-resolution maps of trawling intensity and considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the framework, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of Biological Traits are chosen to determine either the vulnerability of the benthos to the impact of that gear component, or to provide a proxy for their ecological role. The approach considers gear elements, such as otter boards, twin trawl clump, and groundrope, and sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a Biological-Trait approach that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics, dispersal), and their ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the Sublittoral mud (EUNIS A5.3) is affected the most due to the combined effect of intensive fishing and large proportions of long-lived taxa
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Fishing Sea-bed Habitat Risk Assessment (A framework towards the quantitative assessment of trawling impact on the sea-bed and benthic ecosystem)
2015Co-Authors: Adriaan D. Rijnsdorp, Stefan G Bolam, Jan Geert Hiddink, Katell G. Hamon, Ole Ritzau Eigaard, Francois Bastardie, Niels T Hintzen, Ana Ivanovic, Lene Buhl-mortensen, Andrew KennyAbstract:A framework to assess the impact of mobile fishing gear on the seabed and benthic ecosystem is presented. The framework that can be used at regional and local scales considers the physical effects of trawl gears on the seabed, on marine taxa and the functioning of the benthic ecosystem. A reductionist approach is applied that breaks down a fishing gear in its components and distinguishes a number of Biological Traits that are chosen to determine the vulnerability of benthos for the impact of a gear component or to provide a proxy for their ecological role. The approach considers a wide variety of gear elements, such as otter boards, twin trawl clump and ground-rope, and, sweeps that herd the fish. The physical impact of these elements on the seabed, comprising scraping of the seabed, sediment mobilisation and penetration, are a function of the mass, size and speed of the individual component. The impact of the elements on the benthic community are quantified using a Biological-Trait approach, that considers the vulnerability of the benthic community to trawl impact (e.g. sediment position, morphology), the recovery rate (e.g. longevity, maturation age, reproductive characteristics) and the ecological role. The framework is explored to compare the indicators for pressure and ecological impact of bottom trawling in three main seabed habitat types in the North Sea. Preliminary results show that the sublittoral mud habitat is impacted most due to the combined effect of an intensive fishing and high proportions of long-lived taxa.
Vincent H Resh - One of the best experts on this subject based on the ideXlab platform.
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changes in occurrence richness and Biological Traits of dragonflies and damselflies odonata in california and nevada over the past century
Biodiversity and Conservation, 2014Co-Authors: Joan E Balldamerow, Leithen K Mgonigle, Vincent H ReshAbstract:Increases in water demand, urbanization, and severity of drought threaten freshwater ecosystems of the arid western United States. Historical assessments of change in assemblages over time can help determine the effects of these stressors but, to date, are rare. In the present study, we resurveyed 45 sites originally sampled in 1914–1915 for Odonata (dragonflies and damselflies) adults throughout central California and northwestern Nevada, USA. We examined changes in species occurrence rates, taxonomic richness, and Biological Trait composition in relation to climate changes and human population increases. While species richness at individual sites did not change significantly, we found that odonate assemblages have become more similar across sites. Homogenization is a result of the expansion of highly mobile habitat generalists, and the decline of both habitat specialists and species with an overwintering diapause stage. Using a multi-species mixed-effects model, we found that overall occurrences of Odonata increased with higher minimum temperatures. Habitat specialists and species with a diapause stage, however, occurred less often in warmer regions and more often in areas with higher precipitation. Habitat specialists occurred less often in highly populated sites. Life history Traits of Odonata, such as dispersal ability, habitat specialization, and diapause, are useful predictors of species-specific responses to urbanization and climate change in this region.
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Biological Traits of benthic macroinvertebrates in California mediterranean-climate streams: long-term annual variability and Trait diversity patterns
Fundamental and Applied Limnology, 2007Co-Authors: Leah A. Bêche, Vincent H ReshAbstract:We examined long-term variability of the Biological Traits of benthic macroinvertebrate communities using data collected annually (20-, 7-, and 8-years in duration, respectively) from three study regions in northern California's mediterranean-climate region. We related temporal variability to several climatic and physical variables representing precipitation and hydrologic conditions, and assessed the stability of Biological-Trait composition using time-lag regression analysis. We also examined the temporal variability of Trait diversity metrics and their relationship to taxa richness. Trait modalities exhibited high temporal variability (∼ 20 % of all Trait modalities had a CV > 50 %) and Biological-Trait composition varied along a gradient from dry (extreme drought) to wet (above average) years. Traits conferring resistance or resilience to drying (e.g. desiccation resistance, aerial respiration) were more common in drought years, whereas Traits conferring resistance or resilience to floods (e.g. flattened body shape, drift dispersal) were more common in wet years. Furthermore, prolonged drought and the patterns of increasing or decreasing precipitation over time in the study regions resulted in patterns of directional change in Biological-Trait composition. Although Biological Traits had high temporal variation within each region, between-region variation was higher than temporal variation in a single region. As found in other studies, Trait diversity and richness metrics were relatively invariable over time despite high taxonomic turnover. However, there was considerable regional variation in Trait diversity metrics along a gradient of increasing taxonomic diversity. The four functional metrics studied showed high redundancy. Taxa richness was positively correlated with three functional metrics (Trait richness and two Trait diversity measures), and Trait richness and diversity became saturated taxa richness increased (∼50 taxa). In communities largely controlled by abiotic factors, such as stream invertebrates in mediterranean-climate, high redundancy may be the result of strong filtering of Traits at larger spatial scales.
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long term seasonal variation in the Biological Traits of benthic macroinvertebrates in two mediterranean climate streams in california u s a
Freshwater Biology, 2006Co-Authors: Leah A. Bêche, Eric P Mcelravy, Vincent H ReshAbstract:Summary 1. We investigated the seasonal variation of Biological Traits and the influence of interannual rainfall variability on this pattern. Using long-term survey data (6–19 years) from an intermittent and a perennial stream in the Mediterranean-climate region of northern California, we examined 16 fuzzy-coded Biological Traits (e.g. maximum size, life cycle duration, and mode of respiration). 2. Seasonal habitat variability is higher in the intermittent stream than in the perennial stream. During the winter and spring wet-season both streams flood; however, during the summer dry-season, the intermittent stream forms isolated pools in (occasionally drying completely). 3. Seasonal habitat variability influenced both taxonomic and Biological Trait composition. Distinct taxonomic communities were present in each season, particularly in the intermittent stream. The intermittent stream also exhibited more seasonal variation in Biological Traits than the perennial stream. 4. Despite statistically significant seasonal variation, Trait composition was relatively stable among seasons in comparison with taxonomic composition and abundance. Taxonomic composition varied considerably between seasons, because of high seasonal and interannual replacement of taxa resulting from seasonal habitat changes. 5. The seasonality of taxonomic composition and abundance was sensitive to interannual rainfall variability. In dry years, the taxonomic composition of communities was more similar between seasons than in wet years, while Trait composition was relatively insensitive to rainfall variability. 6. Despite high seasonal variation in abundance and taxonomic composition, Biological Traits of aquatic macroinvertebrates varied less and exhibited seasonal stability, which may be a result of the unpredictability and harshness of stream environments.