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Progress towards larval fish-based metrics to identify habitat impairment and assess restoration effectiveness
Citation:
Peterson, G., T. Angradi, A. Trebitz, C. Hatzenbuhler, J. Barge, B. Dawson, M. Pearson, J. Launspach, AND J. Hoffman. Progress towards larval fish-based metrics to identify habitat impairment and assess restoration effectiveness. St. Louis River Summit, Superior, WI, March 05 - 06, 2019.
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:
Determining the need for, and effectiveness of aquatic habitat restoration is an important component in evaluating progress towards removal of a habitat-related Beneficial Use Impairment. 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. Larval fish, however, may serve as a habitat-specific and sensitive biological indicator for assessing degradation and restoration outcomes since larvae are less mobile than juveniles or adults, and spawning and nursery habitat requirements are often specific. In July 2018, 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), from Erie Pier to Mud lake. 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. Analysis of these data is ongoing and will be used to develop survey designs and evaluate metrics to identify habitat impairment and assess restoration effectiveness. These data will also improve our understanding of SLRE larval fish community-habitat relationships, and could serve as a pre-restoration benchmark at current and potential restoration sites.