A toolkit for optimizing fish passage barrier mitigation actions

1. The presence of dams, stream–road crossings and other infrastructure often compromises the connectivity of rivers, leading to reduced fish abundance and diversity. The assessment and mitigation of river barriers is critical to the success of restoration efforts aimed at restoring river integrity. 2. In this study, we present a combined modelling approach involving statistical regression methods and mixed integer linear programming to maximize resident fish species richness within a catchment through targeted barrier mitigation. Compared to existing approaches, our proposed method provides enhanced biological realism while avoiding the use of complex and computationally intensive population/ecosystem models. 3. To estimate barrier passability quickly and at low cost, we further outline a rapid barrier assessment methodology. The methodology is used to characterize potential passage barriers for various fish species common to the UK but can be readily adapted to different planning areas and other species of interest. 4. We demonstrate the applicability of our barrier assessment and prioritization approach based on a case study of the River Wey, located in south-east England. We find that significant increases in species richness can be achieved for modest investment in barrier mitigation. In particular, dams and weirs with low passability located on mid- to high-order streams are identified as top priorities for mitigation. 5. Synthesis and applications. Our study shows the benefits of combining a coarse resolution barrier assessment methodology with state-of-the-art optimization modelling to cost-effectively plan fish passage barrier mitigation actions. The modelling approach can help inform on-the-ground river restoration decision-making by providing a recommended course of action that best allocates limited resources in order to restore longitudinal connectivity and maximize ecological gains

Pet Project or Best Project? Online Decision Support Tools for Prioritizing Barrier Removals in the Great Lakes and Beyond

Structures that block movement of fish through river networks are built to serve a variety of societal needs, including transportation, hydroelectric power, and exclusion of exotic species. Due to their abundance, road crossings and dams reduce the amount of habitat available to fish that migrate from the sea or lakes into rivers to breed. The benefits to fish of removing any particular barrier depends on its location within the river network, its passability to fish, and the relative position of other barriers within the network. Balancing the trade-offs between ecological and societal values makes choosing among potential removal projects difficult. To facilitate prioritization of barrier removals, we developed an online decision support tool (DST) with three functions: (1) view existing barriers at various spatial scales; (2) modify information about barriers, including removal costs; and (3) run optimization models to identify portfolios of removals that provide the greatest amount of habitat access for a given budget. A survey of available DSTs addressing barrier removal prioritization indicates that barrier visualization is becoming widespread but few tools allow dynamic calculation of connectivity metrics, scenario analysis, or optimization. Having these additional functions, our DST enables organizations to develop barrier removal priorities based on cost-effectiveness in restoring aquatic connectivity

Primary Consumer Stable Nitrogen Isotopes as Indicators of Nutrient Source

Non-point source loading of nitrogen and phosphorus is a primary cause of eutrophication of inland waters, although the diffuse and variable nature of nutrient inputs makes it difficult to trace and identify nutrient pathways. Stable nitrogen isotope values (δ15N) in aquatic biota are thought to reflect anthropogenic nutrient inputs, and they may be a promising tool for tracing nutrient sources in watersheds. We measured δ15N of aquatic consumers from a suite of 27 Danish lakes spanning a range of trophic states (oligotrophic to eutrophic) and land uses (forest, urban, agriculture). Primary consumer δ15N values (PCδ15N) varied more than 14‰ among lakes. Models of PCδ15N were developed from limnological, nitrogen loading, and nitrogen source variables using an information-theoretic approach (Akaike\u27s Information Criteria, AIC). Models based on land use/land cover performed best, indicating that elevated δ15N is not only associated with high nitrogen loading, but is also reflective of nitrogen source. Urban and agricultural land use in the watershed, and particularly within the riparian buffer areas, was quantitatively linked to elevated biotic δ15N

Primary Consumer Stable Nitrogen Isotopes as Indicators of Nutrient Source

Non-point source loading of nitrogen and phosphorus is a primary cause of eutrophication of inland waters, although the diffuse and variable nature of nutrient inputs makes it difficult to trace and identify nutrient pathways. Stable nitrogen isotope values (δ15N) in aquatic biota are thought to reflect anthropogenic nutrient inputs, and they may be a promising tool for tracing nutrient sources in watersheds. We measured δ15N of aquatic consumers from a suite of 27 Danish lakes spanning a range of trophic states (oligotrophic to eutrophic) and land uses (forest, urban, agriculture). Primary consumer δ15N values (PCδ15N) varied more than 14‰ among lakes. Models of PCδ15N were developed from limnological, nitrogen loading, and nitrogen source variables using an information-theoretic approach (Akaike\u27s Information Criteria, AIC). Models based on land use/land cover performed best, indicating that elevated δ15N is not only associated with high nitrogen loading, but is also reflective of nitrogen source. Urban and agricultural land use in the watershed, and particularly within the riparian buffer areas, was quantitatively linked to elevated biotic δ15N

Data from: A toolkit for optimizing fish passage barrier mitigation actions

The presence of dams, stream&ndash;road crossings and other infrastructure often compromises the connectivity of rivers, leading to reduced fish abundance and diversity. The assessment and mitigation of river barriers is critical to the success of restoration efforts aimed at restoring river integrity. In this study, we present a combined modelling approach involving statistical regression methods and mixed integer linear programming to maximize resident fish species richness within a catchment through targeted barrier mitigation. Compared to existing approaches, our proposed method provides enhanced biological realism while avoiding the use of complex and computationally intensive population/ecosystem models. To estimate barrier passability quickly and at low cost, we further outline a rapid barrier assessment methodology. The methodology is used to characterize potential passage barriers for various fish species common to the UK but can be readily adapted to different planning areas and other species of interest. We demonstrate the applicability of our barrier assessment and prioritization approach based on a case study of the River Wey, located in south-east England. We find that significant increases in species richness can be achieved for modest investment in barrier mitigation. In particular, dams and weirs with low passability located on mid- to high-order streams are identified as top priorities for mitigation. Synthesis and applications. Our study shows the benefits of combining a coarse resolution barrier assessment methodology with state-of-the-art optimization modelling to cost-effectively plan fish passage barrier mitigation actions. The modelling approach can help inform on-the-ground river restoration decision-making by providing a recommended course of action that best allocates limited resources in order to restore longitudinal connectivity and maximize ecological gains.,River Wey Fish Sampling DataRiver Wey fish sampling dataset used in species richness regression analysis (King et al. 2016).River Wey Barrier DataRiver Wey barrier dataset used in barrier optimization analysis (King et al. 2016).OPL modelCPLEX Studio OPL project, including (.mod), data (.dat), settings (.ops) files, and Excel (.xlsx) files, used in performing optimization analysis (King et al. 2016).,</span

Surface-water-resources information for the Ho-Chunk Nation lands and vicinity, Wisconsin /

Includes bibliographical references (p. 5-7).Mode of access: Internet

Lake hydrodynamics intensify the potential impact of watershed pollutants on coastal ecosystem services

Watersheds deliver numerous pollutants to the coastline of oceans and lakes, thereby jeopardizing ecosystem services. Regulatory frameworks for stressors often focus on loading rates without accounting for the physical dynamics of the receiving water body. Here, we use a three-dimensional hydrodynamic model to simulate the transport of a generic tributary-delivered anthropogenic pollutant within Lake Michigan based on the location and timing of loading. Simulating pollutant plumes from 11 rivers, and their intersections with coastal ecosystem services, reveals strong mediation of potential impacts by lake physics. Trapped pollutants accumulate in nearshore waters during spring peak flows, and become diluted by spreading offshore during the summer. The threat to coastal ecosystem services posed by pollutant loading differs sharply among rivers; high potential impact arises from the spatiotemporal coincidence of tributary input rates, lake mixing dynamics, and multiple human uses of the shoreline. Simultaneous pollution from multiple rivers yields overlapping plumes, creating a second way in which lake hydrodynamics can amplify potential impacts on coastal ecosystem services. Our simulations demonstrate that the physical dynamics of large water bodies can create a dynamic stressor landscape arising from multiple independent sources of non-point-source pollution. The design and implementation of pollution regulations rarely account for spatial and temporal complexities of load processing in receiving waters, yet the resulting variability is likely to strongly mediate impacts on society. As hydrodynamic models improve, our analytical framework could be applied to a wide range of pollutants and waterbodies to enhance the sustainable use of coastal ecosystems