Date of Submission

5-2019

Document Type

Thesis

Degree Name

Master of Science in Environmental Science

Department

Biology and Environmental Sciences

Advisor

Dr. Roman Zajac

Keywords

Genus Fundulus, Small-scale patterns, Salt marsh loss and alteration, Sea level rise and urbanization, Variable habitats

MeSH

Fundulidae, Ecosystem

LCSH

Nekton, Fundulus, Salt marsh ecology, Sea level, Habitat conservation

Abstract

Large scale habitat use patterns of salt marsh nekton are fairly well understood, but small-scale patterns within marsh habitats are not as well known, including the genus Fundulus, an important salt marsh species. This is an area of study that needs more research, particularly in light of increases in salt marshes loss within the last several decades. Salt marshes are a primary habitat for Fundulus species. Sea level rise and urbanization have been major contributors to salt marsh loss and alteration.

Salt marshes are highly variable habitats both spatially and temporally due to tidal cycles, high and low marsh areas and vegetation differences relative to their distances from sub-creeks/mosquito ditches and main creeks. Changes in Fundulus abundance was assessed from 2015 to 2018 during summer and fall. In this study, nets and underwater cameras were used to collect samples of nekton in high, low and sub-tidal creek habitats within the salt marshes in Branford, Connecticut. Nekton abundances and specifically Fundulus abundance were assessed relative to season, depth of water, vegetation coverage, and spatial differences from sub-tidal creeks/mosquito ditches and main creeks. Fundulus size was also compared to the above variables.

Nekton, and specifically Fundulus abundance, varied considerable both spatially and temporally. Nekton and Fundulus abundances were greatest in the fall across the marshes sampled. Nekton and Fundulus abundances were significantly higher in high marsh areas, which were 30 cm and greater in water depth during high tide, as well as a significantly lower in abundance at 9.9 cm and below. Fundulus were larger during the fall compared to summer. Fundulus 3.15 cm or less in length was more abundant on the high marsh further from subcreeks (41 m). Smaller fish (below 3.15 cm) also were found greater abundances in areas of higher vegetation coverage.

Assessing how nekton is responding to salt marsh change due to sea level rise and other global change phenomena. Nekton, like Fundulus, are critical components of Atlantic Coast salt marshes and as such we need to understand their dynamics in the face of such changes in order to assess what conservation and mitigation approaches might be best to preserve their populations and ecosystem functions.

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