Identifier

etd-04092008-131720

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Recently we have begun to understand the importance of inshore hard-bottom substrate, including oyster reefs, to estuarine fish communities in the Gulf of Mexico, especially in the context of identifying Essential Fish Habitat (EFH). However, problems such as habitat loss, disease, overharvest, and failure to replace shell have severely decreased the amount of high-relief oyster reef habitat available to finfish. The purpose of this project was to establish an artificial high-relief mimic-oyster reef in Barataria Bay, Louisiana, and monitor its use by economically and ecologically important finfish, including spotted seatrout (Cynoscion nebulosus) and Atlantic croaker (Micropogonias undulatus). The finfish and invertebrate communities over the artificial reef site were compared to a mud bottom reference site, using two different gear types to sample the entire water column. I also examined site-specific trophic linkages by enumerating gut contents and performing stable isotope analyses of spotted seatrout, Atlantic croaker and bay anchovy (Anchoa mitchilli). There was no overall difference in the community structure between sites, though there was a seasonal difference in the numbers of individuals found at both sites. Species richness also varied by season, with highest number of species present in summer months. Results of the gut-content analysis showed that diets of spotted seatrout do not differ significantly between sites. Spotted seatrout consumed mostly fish and anchovies by number, and penaeid shrimp by weight. Stable isotope analysis indicated that while there were no overall differences in mean stable isotope values, the dietary breadth of spotted seatrout was greater over the artificial reef. In contrast, results indicated that there were significant differences in the diets Atlantic croaker between sites. Atlantic croaker diets consisted of mud crabs (Xanthidae) and other, unidentifiable crabs over the reef, and bivalves and fish over the reference site. Stable isotope analysis of Atlantic croaker indicates that overall dietary breadth was similar between sites, though 15N values were significantly higher over the artificial reef. Results of the stable isotope analysis for bay anchovy indicate that there was a greater dietary breath over the artificial reef.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

James H. Cowan Jr.

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