Identifier

etd-05232014-211726

Degree

Master of Science (MS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Habitat quality of natural and artificial reefs for red snapper (Lutjanus campechanus) in the northwestern Gulf of Mexico (Gulf) is important as this area is home to the majority of the Gulf’s artificial reef system, in the form of oil and gas platforms, in addition to the largest extent of high vertical relief natural habitat. This study sought to assess habitat quality of natural reefs of varying habitat complexity and an artificial reef complex located on the LA continental shelf. Habitat quality was assessed by comparing red snapper diets and foraging patterns, and nutritional condition using the liver-somatic index (LSI) and caloric densities. The diets at the natural reefs consisted of primarily fish, while the diets at the artificial reefs consisted of primarily fish and zooplankton. Size class was not an important factor for the diets at the natural reefs, but the diet varied between size classes at the artificial reefs. The natural reefs were found to offer a wider diversity of prey items, and reef-dependent species were found only in the diets at the natural reefs. Differences between diets at the natural and artificial reefs reflected differences between the substrates found at each habitat. Red snapper at the natural reefs were found to feed on and above the reef, while feeding at the artificial reefs was predominantly along the surrounding seafloor and water column. Site-specific temporal patterns in both the LSI and caloric density were evident. The LSI of females at the natural reefs was greater than the LSI of females at the artificial reefs. While caloric density statistically differed between habitats and sizes, the differences between values may not be biologically significant. Female red snapper at the natural reefs appear to be in a better nutritional condition than females at the artificial reefs. Results of this study indicate that natural reefs on the LA continental shelf provide high habitat quality for red snapper. To maximize reproductive output, the better-quality foraging and nutritional condition of red snapper at the natural reefs should be taken into account when evaluating potential areas for the Flower Garden Banks National Marine Sanctuary status.

Date

2014

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cowan, James H

DOI

10.31390/gradschool_theses.3527

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