Date of Award

12-2021

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Ocean Engineering and Marine Sciences

First Advisor

Kevin Johnson

Second Advisor

Kelli Hunsucker

Third Advisor

Glenn Miller

Fourth Advisor

Richard Aronson

Abstract

The Indian River Lagoon (IRL) has been degraded by decades of eutrophication, and has accumulated an abundance of fine-grained, organic-rich sediments (muck). To quantify the impacts of organic sediments and environmental dredging, benthic mollusks were chosen to serve as bioindicators of environmental change, sediment health, and water quality. Data on species richness, biodiversity, and abundances was collected alongside sediment and water quality data before, during and after dredging. Organic sediment content was found to have an inverse logarithmic relationship benthic mollusk biodiversity, species richness, and abundance. Sediments low in percent organic content (0.7% to 6.1%) were located near the adjacent seagrass beds. Sediments with lower organic content generally had higher biodiversity (up to 1.337). Sediments with higher organic content generally had low biodiversity (0-0.6667). These biological correlations were analogously observed with sediment silt-clay (%) and sediment water content (%). However, variability was high and no significant pre- vs. post-dredging differences were observed in the community data. Post-hoc analyses found that percent dissolved oxygen was responsible for 29.31-34.12% of the variation in the benthic mollusk community data.

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