Theses and Dissertations


Title: DIEL FEEDING FEEDING PATTERNS OF RED SNAPPER, Lutjanus campechanus, ON ARTIFICIAL REEFS IN THE NORTHCENTRAL GULF OF MEXICO

Name: Ouzts, Allyson Clair

Degree: MS

Chair: Stephen T. Szedimayer

Resides:

University: Auburn University

Location: Auburn, Alabama

Date: 2002

Pages: 74

Keywords: Red snapper,diet,feeding periods,stomach analysis,artificial reef

Abstract:

Red snapper, Lutjanus campechanus, diets were compared among four different feeding periods (dawn, day, dusk, and night). Stomach samples were taken August through October by trap and hook & line from artificial reefs in the north central Gulf of Mexico. A total of 456 stomachs were examined of which 179 (39%) contained prey. A percent Index of Relative Importance (% IRI) was calculated from percent number, percent volume, and percent weight for each prey taxon. Red snapper diets were also compared among five different reefs and three fish size classes: small (200-299), medium (300-399), and large (400-499 mm SL). Mean gut fullness was significantly lower for the dusk period compared to other time periods. Fish were the most important prey group for dawn, day, and dusk periods. Crabs were the most important prey taxon at night and were the second most important prey for dusk and dawn periods. Red snapper diets also varied among reefs. Fish dominated diets at reefs one, four, and five. Crabs dominated diets on reef two, but they were completely absent from reef three. Pteropods and tunicates dominated diets on reef three but were absent on all other reefs. Red snapper size class was more important in determining diets compared to feeding period based on multidimensional scaling analysis. Diets of small red snapper were dominated by fish for both day and night periods. Medium sized red snapper fed on fish and tunicates in the day but switched to fish and crabs at night. At night, crabs also dominated the diets of large red snapper. Small red snapper fed on the reef prey types in both day and night periods. Reef and pelagic prey dominated the diets of medium red snapper in the day, but at night, both medium and large red snapper fed on prey from sand, reef, and mixed habitats. Diel samples of red snapper stomach contents showed significant differences, thus care should be taken when making conclusions based on day time samples. Also, red snapper showed significant feeding on reef associated prey, and they are probably obtaining at least some nutrition from resources that would not be available without the presence of artificial reefs.

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