The Experts below are selected from a list of 10587 Experts worldwide ranked by ideXlab platform
Simon Blanchet - One of the best experts on this subject based on the ideXlab platform.
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The relative contribution of river network structure and Anthropogenic Stressors to spatial patterns of genetic diversity in two freshwater fishes: A multiple-Stressors approach
Freshwater Biology, 2018Co-Authors: Jérôme G. Prunier, Vincent Dubut, Géraldine Loot, Loïc Tudesque, Simon BlanchetAbstract:1. Recent findings highlighted the central role of the structure of the river network in shaping spatial patterns of genetic diversity in riverscapes. However, the influence of multiple Anthropogenic Stressors on these patterns may be just as important and the relative impacts of these two types of predictors have rarely been quantified simultaneously in river networks. Here, we contributed to filling this gap by investigating the relative contribution of both network structure and multiple Anthropogenic Stressors in shaping spatial patterns of genetic diversity in two freshwater fishes (Gobio occitaniae and Phoxinus phoxinus). 2. We focused on two rivers in which the two fish species were sampled along the upstream–downstream gradient. Microsatellite markers were used to quantify genetic diversity from three indices: allelic richness, private allelic richness and genetic uniqueness. Each sampling site was physically characterised according to its position in the network, and was described for multiple Anthropogenic Stressors including habitat degradation, fragmentation and stocking. This multiple-Stressors approach was conducted using a fully explicit and generalisable analytical framework designed to cope with strong collinearity among environmental variables. 3. Overall, the contribution of network structure to the variance in genetic diversity was 1.8 times higher than the contribution of Anthropogenic Stressors. Both the position of sites along the upstream–downstream gradient and stocking were strong and consistent drivers of genetic variability. Conversely, the local influences of habitat degradation and fragmentation were species-and river-specific, sometimes even varying along the river channel, thus preventing any generalisations. 4. We concluded that the natural structure of networks and stocking strongly influence spatial patterns of genetic diversity in a predictable way, whereas the influence of other human activities may be much more difficult to predict over species and contexts. K E Y W O R D S commonality analysis, freshwater fish, landscape genetics, meta-analysis, stocking
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The relative contribution of river network structure and Anthropogenic Stressors to spatial patterns of genetic diversity in two freshwater fishes: A multiple‐Stressors approach
Freshwater Biology, 2017Co-Authors: Jérôme G. Prunier, Vincent Dubut, Géraldine Loot, Loïc Tudesque, Simon BlanchetAbstract:Recent findings highlighted the central role of the structure of the river network in shaping spatial patterns of genetic diversity in riverscapes. However, the influence of multiple Anthropogenic Stressors on these patterns may be just as important and the relative impacts of these two types of predictors have rarely been quantified simultaneously in river networks. Here, we contributed to filling this gap by investigating the relative contribution of both network structure and multiple Anthropogenic Stressors in shaping spatial patterns of genetic diversity in two freshwater fishes (Gobio occitaniae and Phoxinus phoxinus). We focused on two rivers in which the two fish species were sampled along the upstream–downstream gradient. Microsatellite markers were used to quantify genetic diversity from three indices: allelic richness, private allelic richness and genetic uniqueness. Each sampling site was physically characterised according to its position in the network, and was described for multiple Anthropogenic Stressors including habitat degradation, fragmentation and stocking. This multiple-Stressors approach was conducted using a fully explicit and generalisable analytical framework designed to cope with strong collinearity among environmental variables. Overall, the contribution of network structure to the variance in genetic diversity was 1.8 times higher than the contribution of Anthropogenic Stressors. Both the position of sites along the upstream–downstream gradient and stocking were strong and consistent drivers of genetic variability. Conversely, the local influences of habitat degradation and fragmentation were species- and river-specific, sometimes even varying along the river channel, thus preventing any generalisations. We concluded that the natural structure of networks and stocking strongly influence spatial patterns of genetic diversity in a predictable way, whereas the influence of other human activities may be much more difficult to predict over species and contexts.
Vincent H. Resh - One of the best experts on this subject based on the ideXlab platform.
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climatic influences and Anthropogenic Stressors an integrated framework for streamflow management in mediterranean climate california u s a
Freshwater Biology, 2010Co-Authors: Theodore E. Grantham, Adina M. Merenlender, Vincent H. ReshAbstract:Summary 1. In Mediterranean and other water-stressed climates, water management is critical to the conservation of freshwater ecosystems. To secure and maintain water allocations for the environment, integrated water management approaches are needed that consider ecosystem flow requirements, patterns of human water demands and the temporal and spatial dynamics of water availability. 2. Human settlements in Mediterranean climates have constructed water storage and conveyance projects at a scale and level of complexity far exceeding those in other, less seasonal climates. As a result, multiple ecological Stressors associated with natural periods of flooding and drying are compounded by Anthropogenic impacts resulting from water infrastructure development. 3. Despite substantial investments in freshwater ecosystem conservation, particularly in California, U.S.A., success has been limited because the scales at which river management and restoration are implemented are often discordant with the temporal and spatial scales at which ecosystem processes operate. Often, there is also strong social and political resistance to restricting water allocation to existing consumptive uses for environmental protection purposes. Furthermore, institutions rarely have the capacity to develop and implement integrated management programmes needed for freshwater ecosystem conservation. 4. We propose an integrated framework for streamflow management that explicitly considers the temporal and spatial dynamics of water supply and needs of both human and natural systems. This approach makes it possible to assess the effects of alternative management strategies to human water security and ecosystem conditions and facilitates integrated decision-making by water management institutions. 5. We illustrate the framework by applying a GIS-based hydrologic model in a Mediterranean-climate watershed in Sonoma County, California, U.S.A. The model is designed to assess the hydrologic impacts of multiple water users distributed throughout a stream network. We analyse the effects of vineyard water management on environmental flows to (i) evaluate streamflow impacts from small storage ponds designed to meet human water demands and reduce summer diversions, (ii) prioritise the placement of storage ponds to meet human water needs while optimising environmental flow benefits and (iii) examine the environmental and social consequences of flow management policies designed to regulate the timing of diversions to protect ecosystem functions. 6. Thematic implications: spatially explicit models that represent Anthropogenic Stressors (e.g. water diversions) and environmental flow needs are required to address persistent and growing threats to freshwater biodiversity. A coupled human–natural system approach to water management is particularly useful in Mediterranean climates, characterised by severe competition for water resources and high spatial and temporal variability in flow regimes. However, lessons learned from our analyses are applicable to other highly seasonal systems and those that are expected to have increased precipitation variability resulting from climate change.
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Climatic influences and Anthropogenic Stressors: an integrated framework for streamflow management in Mediterranean‐climate California, U.S.A.
Freshwater Biology, 2010Co-Authors: Theodore E. Grantham, Adina M. Merenlender, Vincent H. ReshAbstract:Summary 1. In Mediterranean and other water-stressed climates, water management is critical to the conservation of freshwater ecosystems. To secure and maintain water allocations for the environment, integrated water management approaches are needed that consider ecosystem flow requirements, patterns of human water demands and the temporal and spatial dynamics of water availability. 2. Human settlements in Mediterranean climates have constructed water storage and conveyance projects at a scale and level of complexity far exceeding those in other, less seasonal climates. As a result, multiple ecological Stressors associated with natural periods of flooding and drying are compounded by Anthropogenic impacts resulting from water infrastructure development. 3. Despite substantial investments in freshwater ecosystem conservation, particularly in California, U.S.A., success has been limited because the scales at which river management and restoration are implemented are often discordant with the temporal and spatial scales at which ecosystem processes operate. Often, there is also strong social and political resistance to restricting water allocation to existing consumptive uses for environmental protection purposes. Furthermore, institutions rarely have the capacity to develop and implement integrated management programmes needed for freshwater ecosystem conservation. 4. We propose an integrated framework for streamflow management that explicitly considers the temporal and spatial dynamics of water supply and needs of both human and natural systems. This approach makes it possible to assess the effects of alternative management strategies to human water security and ecosystem conditions and facilitates integrated decision-making by water management institutions. 5. We illustrate the framework by applying a GIS-based hydrologic model in a Mediterranean-climate watershed in Sonoma County, California, U.S.A. The model is designed to assess the hydrologic impacts of multiple water users distributed throughout a stream network. We analyse the effects of vineyard water management on environmental flows to (i) evaluate streamflow impacts from small storage ponds designed to meet human water demands and reduce summer diversions, (ii) prioritise the placement of storage ponds to meet human water needs while optimising environmental flow benefits and (iii) examine the environmental and social consequences of flow management policies designed to regulate the timing of diversions to protect ecosystem functions. 6. Thematic implications: spatially explicit models that represent Anthropogenic Stressors (e.g. water diversions) and environmental flow needs are required to address persistent and growing threats to freshwater biodiversity. A coupled human–natural system approach to water management is particularly useful in Mediterranean climates, characterised by severe competition for water resources and high spatial and temporal variability in flow regimes. However, lessons learned from our analyses are applicable to other highly seasonal systems and those that are expected to have increased precipitation variability resulting from climate change.
Noel P D Juvignykhenafou - One of the best experts on this subject based on the ideXlab platform.
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impacts of multiple Anthropogenic Stressors on stream macroinvertebrate community composition and functional diversity
Ecology and Evolution, 2021Co-Authors: Noel P D Juvignykhenafou, Jeremy J Piggott, David Atkinson, Yixin Zhang, Samuel J Macaulay, Christoph D MatthaeiAbstract:Ensuring the provision of essential ecosystem services in systems affected by multiple Stressors is a key challenge for theoretical and applied ecology. Trait-based approaches have increasingly been used in multiple-stressor research in freshwaters because they potentially provide a powerful method to explore the mechanisms underlying changes in populations and communities. Individual benthic macroinvertebrate traits associated with mobility, life history, morphology, and feeding habits are often used to determine how environmental drivers structure stream communities. However, to date multiple-stressor research on stream invertebrates has focused more on taxonomic than on functional metrics. We conducted a fully crossed, 4-factor experiment in 64 stream mesocosms fed by a pristine montane stream (21 days of colonization, 21 days of manipulations) and investigated the effects of nutrient enrichment, flow velocity reduction and sedimentation on invertebrate community, taxon, functional diversity and trait variables after 2 and 3 weeks of stressor exposure. 89% of the community structure metrics, 59% of the common taxa, 50% of functional diversity metrics, and 79% of functional traits responded to at least one stressor each. Deposited fine sediment and flow velocity reduction had the strongest impacts, affecting invertebrate abundances and diversity, and their effects translated into a reduction of functional redundancy. Stressor effects often varied between sampling occasions, further complicating the prediction of multiple-stressor effects on communities. Overall, our study suggests that future research combining community, trait, and functional diversity assessments can improve our understanding of multiple-stressor effects and their interactions in running waters.
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Anthropogenic Stressors affect fungal more than bacterial communities in decaying leaf litter a stream mesocosm experiment
Science of The Total Environment, 2020Co-Authors: Noel P D Juvignykhenafou, Jeremy J Piggott, David Atkinson, Yixin Zhang, Christoph D Matthaei, Sunshine A Van BaelAbstract:Abstract Despite the progress made in environmental microbiology techniques and knowledge, the succession and functional changes of the microbial community under multiple Stressors are still poorly understood. This is a substantial knowledge gap as microbial communities regulate the biogeochemistry of stream ecosystems. Our study assessed the structural and temporal changes in stream fungal and bacterial communities associated with decomposing leaf litter under a multiple-stressor scenario. We conducted a fully crossed 4-factor experiment in 64 flow-through mesocosms fed by a pristine montane stream (21 days of colonisation, 21 days of manipulations) and investigated the effects of nutrient enrichment, flow velocity reduction and sedimentation after 2 and 3 weeks of stressor exposure. We used high-throughput sequencing and metabarcoding techniques (16S and 18S rRNA genes) to identify changes in microbial community composition. Our results indicate that (1) shifts in relative abundances of the pre-existing terrestrial microbial community, rather than changes in community identity, drove the observed responses to Stressors; (2) changes in relative abundances within the microbial community paralleled decomposition rate patterns with time; (3) both fungal and bacterial communities had a certain resistance to Stressors, as indicated by relatively minor changes in alpha diversity or multivariate community structure; (4) overall, stressor interactions were more common than stressor main effects when affecting microbial diversity metrics or abundant individual genera; and (5) stressor effects on microbes often changed from 2 weeks to 3 weeks of stressor exposure, with several response patterns being reversed. Our study suggests that future research should focus more on understanding the temporal dynamics of fungal and bacterial communities and how they relate to ecosystem processes to advance our understanding of the mechanisms associated with multiple-stressor interactions.
Norman D. Yan - One of the best experts on this subject based on the ideXlab platform.
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decadal scale regional changes in canadian freshwater zooplankton the likely consequence of complex interactions among multiple Anthropogenic Stressors
Freshwater Biology, 2013Co-Authors: Michelle E. Palmer, Norman D. YanAbstract:Summary Ecological integrity is increasingly threatened by multiple Anthropogenic Stressors, but the cumulative impact of Stressors is poorly understood because they can interact in unexpected ways. Knowledge of these interactions and their associated impacts is needed to support the conservation of valued ecosystems. We used a large-scale, replicated field survey and multiple regression analysis to investigate the cumulative impacts of multiple physical, chemical and biological Stressors on the crustacean zooplankton assemblages of 34 Canadian Shield lakes between 1980s and 2004–2005. Zooplankton total abundance, species richness, diversity and community structure, as well as the relative abundances of prominent taxonomic orders of zooplankton, changed at a regional scale. These changes occurred in response to changes in water quality and lake thermal regime, and invasion by an exotic predator. Interactions between Stressors were common and represented an important determinant of zooplankton assemblage changes over time. We provide the first evidence that the individual and combined impacts of multiple Stressors cause regional ecological change over decades. Our results demonstrate the prevalence of stressor interactions in natural environments and highlight the complexity of ecosystem responses to multiple Stressors. Zooplankton changes recorded here may be widespread because climate change, acidification, development and the spread of invasive species are globally pervasive. These changes could have cascading impacts because zooplankton is an essential link in aquatic food webs. Our findings highlight the need to consider the interactive effect of Stressors when assessing Anthropogenic impacts and will inform management and conservation of ecosystems threatened by multiple Stressors.
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Decadal‐scale regional changes in Canadian freshwater zooplankton: the likely consequence of complex interactions among multiple Anthropogenic Stressors
Freshwater Biology, 2013Co-Authors: Michelle E. Palmer, Norman D. YanAbstract:Summary Ecological integrity is increasingly threatened by multiple Anthropogenic Stressors, but the cumulative impact of Stressors is poorly understood because they can interact in unexpected ways. Knowledge of these interactions and their associated impacts is needed to support the conservation of valued ecosystems. We used a large-scale, replicated field survey and multiple regression analysis to investigate the cumulative impacts of multiple physical, chemical and biological Stressors on the crustacean zooplankton assemblages of 34 Canadian Shield lakes between 1980s and 2004–2005. Zooplankton total abundance, species richness, diversity and community structure, as well as the relative abundances of prominent taxonomic orders of zooplankton, changed at a regional scale. These changes occurred in response to changes in water quality and lake thermal regime, and invasion by an exotic predator. Interactions between Stressors were common and represented an important determinant of zooplankton assemblage changes over time. We provide the first evidence that the individual and combined impacts of multiple Stressors cause regional ecological change over decades. Our results demonstrate the prevalence of stressor interactions in natural environments and highlight the complexity of ecosystem responses to multiple Stressors. Zooplankton changes recorded here may be widespread because climate change, acidification, development and the spread of invasive species are globally pervasive. These changes could have cascading impacts because zooplankton is an essential link in aquatic food webs. Our findings highlight the need to consider the interactive effect of Stressors when assessing Anthropogenic impacts and will inform management and conservation of ecosystems threatened by multiple Stressors.
Jérôme G. Prunier - One of the best experts on this subject based on the ideXlab platform.
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The relative contribution of river network structure and Anthropogenic Stressors to spatial patterns of genetic diversity in two freshwater fishes: A multiple-Stressors approach
Freshwater Biology, 2018Co-Authors: Jérôme G. Prunier, Vincent Dubut, Géraldine Loot, Loïc Tudesque, Simon BlanchetAbstract:1. Recent findings highlighted the central role of the structure of the river network in shaping spatial patterns of genetic diversity in riverscapes. However, the influence of multiple Anthropogenic Stressors on these patterns may be just as important and the relative impacts of these two types of predictors have rarely been quantified simultaneously in river networks. Here, we contributed to filling this gap by investigating the relative contribution of both network structure and multiple Anthropogenic Stressors in shaping spatial patterns of genetic diversity in two freshwater fishes (Gobio occitaniae and Phoxinus phoxinus). 2. We focused on two rivers in which the two fish species were sampled along the upstream–downstream gradient. Microsatellite markers were used to quantify genetic diversity from three indices: allelic richness, private allelic richness and genetic uniqueness. Each sampling site was physically characterised according to its position in the network, and was described for multiple Anthropogenic Stressors including habitat degradation, fragmentation and stocking. This multiple-Stressors approach was conducted using a fully explicit and generalisable analytical framework designed to cope with strong collinearity among environmental variables. 3. Overall, the contribution of network structure to the variance in genetic diversity was 1.8 times higher than the contribution of Anthropogenic Stressors. Both the position of sites along the upstream–downstream gradient and stocking were strong and consistent drivers of genetic variability. Conversely, the local influences of habitat degradation and fragmentation were species-and river-specific, sometimes even varying along the river channel, thus preventing any generalisations. 4. We concluded that the natural structure of networks and stocking strongly influence spatial patterns of genetic diversity in a predictable way, whereas the influence of other human activities may be much more difficult to predict over species and contexts. K E Y W O R D S commonality analysis, freshwater fish, landscape genetics, meta-analysis, stocking
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The relative contribution of river network structure and Anthropogenic Stressors to spatial patterns of genetic diversity in two freshwater fishes: A multiple‐Stressors approach
Freshwater Biology, 2017Co-Authors: Jérôme G. Prunier, Vincent Dubut, Géraldine Loot, Loïc Tudesque, Simon BlanchetAbstract:Recent findings highlighted the central role of the structure of the river network in shaping spatial patterns of genetic diversity in riverscapes. However, the influence of multiple Anthropogenic Stressors on these patterns may be just as important and the relative impacts of these two types of predictors have rarely been quantified simultaneously in river networks. Here, we contributed to filling this gap by investigating the relative contribution of both network structure and multiple Anthropogenic Stressors in shaping spatial patterns of genetic diversity in two freshwater fishes (Gobio occitaniae and Phoxinus phoxinus). We focused on two rivers in which the two fish species were sampled along the upstream–downstream gradient. Microsatellite markers were used to quantify genetic diversity from three indices: allelic richness, private allelic richness and genetic uniqueness. Each sampling site was physically characterised according to its position in the network, and was described for multiple Anthropogenic Stressors including habitat degradation, fragmentation and stocking. This multiple-Stressors approach was conducted using a fully explicit and generalisable analytical framework designed to cope with strong collinearity among environmental variables. Overall, the contribution of network structure to the variance in genetic diversity was 1.8 times higher than the contribution of Anthropogenic Stressors. Both the position of sites along the upstream–downstream gradient and stocking were strong and consistent drivers of genetic variability. Conversely, the local influences of habitat degradation and fragmentation were species- and river-specific, sometimes even varying along the river channel, thus preventing any generalisations. We concluded that the natural structure of networks and stocking strongly influence spatial patterns of genetic diversity in a predictable way, whereas the influence of other human activities may be much more difficult to predict over species and contexts.