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Progress towards larval fish-based metrics for assessing habitat restoration effectiveness
Citation:
Peterson, G., T. Angradi, M. Pearson, A. Trebitz, C. Hatzenbuhler, J. Barge, B. Dawson, M. Gordon, J. Launspach, AND J. Hoffman. Progress towards larval fish-based metrics for assessing habitat restoration effectiveness. St. Louis River Summit, Duluth, MN, March 03 - 04, 2020. https://doi.org/10.23645/epacomptox.11926341
Impact/Purpose:
Determining the need for, and effectiveness of aquatic habitat restoration is an important component in evaluating habitat and sediment remediation projects. Assessing changes to structural habitat elements (e.g., bathymetry, vegetation cover) can be directly measured, but such assessments are challenging for highly mobile biota such as adult or juvenile fish because their range is not limited to the restored habitat. However, healthy gamefish are an important ecosystem service associated with habitat restoration goals, and restoring fish communities and fisheries is a common management goal. In this presentation, we report on progress towards developing larval fish-based metrics to assess coastal wetland habitat restoration, which is the dominant habitat type being restored in Great Lakes Areas of Concern.
Description:
Assessing habitat restoration effectiveness is fundamental to ecosystem-based management for Areas of Concern. Biological metrics that are responsive at the restoration site scale, such as vegetation- and benthic invertebrate-based measures of ecological integrity, are necessary to measure restoration effectiveness. A fish habitat condition metric would be useful; however, adult and juvenile fish-based metrics may not be responsive to project-scale change because the home range of adult and juvenile fish is often larger than the restored habitat. Larval fish, however, may serve as a sensitive biological indicator with the spatial fidelity to assess both degradation and restoration because larvae are less mobile than juveniles or adults. In July 2018 and 2019, we collected larval fish community and habitat data from shallow water stations at 5 “impaired” and 5 “reference” embayments along the St. Louis river estuary (SLRE), including some current and potential restoration sites. Within each embayment, 6 to 10 sampling stations were randomly selected from the available area of shallow (=1.5m depth) habitats. In the SLRE, these habitats are the focus of restoration efforts, support aquatic vegetation, and are effectively sampled by our larval fish tow sled. Hydroacoustics and visual estimates were used to characterize and quantify submerged aquatic vegetation (SAV) at each station. Taxonomic identification of larval fish, and habitat data processing is ongoing for the 2019 sampling, but preliminary analysis of 2018 data suggest that both larval fish abundance and species richness reflect both embayment and station level differences in density and composition of SAV. Results from this study will be used to evaluate larval fish community-habitat relationships aimed at developing metrics to identify habitat impairment and assess restoration effectiveness, in addition to serving as a pre-restoration benchmark for sites where restoration is planned or ongoing.
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DOI: Progress towards larval fish-based metrics for assessing habitat restoration effectiveness