| Summary: | Thesis (M.S.) - Florida Institute of Technology, 2019. The Indian River Lagoon (IRL) has experienced a loss in seagrasses due to organic sediment accumulation and harmful algal blooms. Seagrasses are an essential nursery habitat for many fishes and benthic invertebrates. IRL fish known to utilize benthic habitat and feed on invertebrates include Atlantic croaker (Micropogonias undulates), juvenile Red Drum (Sciaenops ocellatus), and Mojarra (Eucinostomus spp.). The most abundant major infaunal taxa of the IRL are crustaceans, polychaetes, and mollusks. Environmental dredging in the IRL’s Turkey Creek is intended to improve water quality, remove harmful sediments and restore benthic habitat. Such dredging may impact benthic invertebrate populations and, indirectly, their predatory fish species. This study explores the impact of environmental dredging on benthic invertebrates and fish, and attempts to quantify how those impacts affect the food web. This was accomplished by examining how the most abundant infaunal community groups changed in dredged vs. undredged sediments, and whether those sediments had low, medium, or high organic content (“muck” for the latter). Benthic invertebrate populations were sampled and quantified by collecting sediments using a Petite Ponar grab and counting animals >500µm. Abundant taxa found to colonize dredged Turkey Creek muck sediments include amphipods (e.g., Cerapus tubularis and Grandierdiella bonnieroides), bivalves (e.g., Mulinia lateralis and Parastarte triquetra), polychaetes (e.g., Capitella capitata and Glycera americana), and tanaids (e.g., Leptochelia dubia). Densities in dredged muck sites ranged from 0-3,897 ind. m-2 (±0-3,662 SE, p=0.05) for amphipods, 0- 637 ind. m-2 (±0-178 SE, p<0.001) for bivalves, 0-492 ind. m-2 (±0-234 SE, p<0.01) for polychaetes, and 0-148 ind. m-2 (±0-119 SE) for tanaids. Abundant taxa found to colonize dredged Turkey Creek intermediate sediments include amphipods (G. bonnieroides and C. tubularis), bivalves (M. lateralis and P. ...
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