Assessment of Salt Marsh Shoreline Degradation and Restoration on Benthic Invertebrate Infaunal Community Composition

Anna Gerber-Williams, University of Rhode Island

Abstract

The benthic invertebrate infaunal community is sensitive to disturbance and is an indicator for the overall health of estuarine ecosystems. To quantify the effect of salt marsh shoreline stabilization and restoration approaches on adjacent habitat quality, we compared invertebrate community assemblages of benthic infauna between four different shoreline types, two of which were erosion control methods, hardened and living shoreline approach, and two unaltered shorelines, natural and eroded. We quantified benthic infauna density, biomass, richness, and diversity and evaluated physical-chemical factors (water quality, sediment carbon and nitrogen content, and grain size) that may be influencing the benthic invertebrate community associated with the various shoreline treatments. ^ There were significant differences, determined using a one-way ANOVA, (p < 0.05) in benthic infauna density, diversity and richness between shoreline types over all the seasons. Hardened and eroded shorelines had more variability around the mean density, diversity and species richness across all seasons than the living and natural shorelines suggesting that while living and natural shorelines had lower mean overall abundance they provide a more stable habitat for benthic infauna. Natural and Living shorelines had constant predation pressure due to the more complex habitat structure attracting a larger nekton community than eroded and hardened shoreline treatments, which caused a significant reduction in mean abundance of benthic infauna from May to October of 2015 at all treatment sites but overall lower mean density and biomass at the natural and living shorelines. We showed that benthic infauna community indices provided an indication of habitat stability based on changes in species density, biomass, richness, diversity, and functional groups between shoreline treatment sites. This information reflects the ecosystem complexity, which is driven by resource availability and predation. The hardened shoreline provided habitat to a wide array of organisms in comparison to the more specialized feeding guilds found at the natural and living shorelines, indicating that for restoration purposes a hardened shoreline does not provide a stable state of species assemblages as found at the natural shoreline. The findings from this project suggest that the use of living shoreline restoration methods promote habitat complexity similar to that of the natural shoreline and thus similar trends in species density, richness and diversity. There is increasing societal pressure to protect coastal shorelines from erosion, it is important to consider how each restoration method affects benthic infauna, a critical component of the nearshore coastal food web.^

Subject Area

Ecology|Natural resource management

Recommended Citation

Anna Gerber-Williams, "Assessment of Salt Marsh Shoreline Degradation and Restoration on Benthic Invertebrate Infaunal Community Composition" (2017). Dissertations and Master's Theses (Campus Access). Paper AAI10271576.
http://digitalcommons.uri.edu/dissertations/AAI10271576

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