Date of Award

2017

Degree Type

Thesis

Degree Name

Master of Science in Biological and Environmental Sciences (MSBES)

Specialization

Ecology and Ecosystem Science (EES)

Department

Natural Resources Science

First Advisor

Laura A. Meyerson

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, 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 that attracted a larger nekton community than eroded and hardened shoreline treatments. This caused a significant reduction in mean abundance of benthic infauna from May to October of 2015 at all treatment sites but an overall lower mean density and biomass at the natural and living shorelines. Benthic infauna community indices (density, biomass, richness, diversity, and functional groups) differ among shoreline treatment sites reflecting ecosystem complexity that is likely driven by resource availability and predation. The hardened and eroded shorelines provided habitat to a more generalist 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, with more fluctuations in benthic community indices compared with those found at the natural and living shorelines. The findings from this project suggest that the use of living shoreline restoration methods promote habitat complexity similar to that of the natural shoreline resulting in similar trends in species density, richness and diversity. Because benthic infauna are a critical component of the nearshore coastal food web along with increasing societal pressure to protect coastal shorelines from erosion, it is important to consider how restoration methods affect benthic infauna.

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