Date of Award

5-2019

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Marine Biology and Coastal Sciences

Thesis Sponsor/Dissertation Chair/Project Chair

Paul A. X. Bologna

Committee Member

Dirk Vanderklein

Committee Member

Colette Feehan

Abstract

Resiliency projects are being implemented throughout coastal communities with the intention of reducing the loss of salt marsh habitat. Salt marsh enhancement projects may have the benefit of minimizing physical coastal impacts, but enhancement activities are not fully understood as a result of potential impacts on salt marsh ecosystems, particularly nekton or fish and decapod communities. Questions involving salt marsh enhancement remain in regard to negative impacts on nekton communities and hydrologic habitat connectivity. To evaluate the impacts of salt marsh enhancement in reference to nekton community structures, I compared nekton density in restored and non-restored locations on two salt marshes in New Jersey. My results suggest that salt marsh thin-layer placement impacts habitat use, with some habitat features becoming lost for nekton during the initial construction phase. Specifically, greater density of decapods, particularly Palaemonetes pugio (daggerblade grass shrimp), were found post restoration, suggesting that their presence could represent early successional species providing unquestionable ecological importance for transporting energy and nutrients throughout multiple salt marsh trophic levels. Additionally, two years post salt marsh restoration, young of the year Cyprinodon variegatus (sheepshead minnow) and Fundulus majalis (striped killifish) were found utilizing restored salt marsh pools under severe biological thresholds such as low dissolved oxygen and elevated water temperature conditions. In future studies, greater emphasis should be focused on the initial oxygen availability in sediments. Regions exhibiting low oxygen concentrations may influence vegetative species composition and growth. Additionally, reestablishing vegetative cover to areas that receive excess dredged material may be critical to ensure the creation and enhancement of valuable coastal habitats. Lastly, ensuring hydrologic habitat connectivity (i.e., connecting tidal and subtidal creeks with restored salt marsh pools) before placement of dredged material is applied for thin-layer restoration, is critical to ensure maximum habitat availability for nekton species. Clearly, sea level rise can result in salt marsh loss along the coast and thin-layer placement can be used to counter these effects if properly planned and administered appropriately to address plant community restoration and nekton use.

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