Diet and Trophic Ecology of Red Snapper On Natural and Artificial Reefs in the Northern Gulf of Mexico

Red snapper were sampled with hook and line at natural (n=35) and artificial (n=28) reef sites in the northern Gulf of Mexico from 2009-2011. Stomachs (n=708) were extracted and their contents preserved for gut content analysis, and muscle tissue samples (n=200) were dissected and frozen for IR-MS analysis (d¹³C, d ¹⁵N, and d ³⁴S). Forty-eight percent of stomachs had identifiable prey. A PERMANOVA was computed to test the effect of habitat type, depth, fish size and the Deepwater Horizon Oil Spill (DHOS) on red snapper diet. The fish size and the DHOS effect were the only significant (p<0.01)  main effects in the model, but interactions between the DHOS effect and both habitat type and depth also were significant (p<0.02). The DHOS effect was driven by an increase of fish and a decrease of zooplankton in red snapper diet following the spill. Stable isotope data also indicated an increase in red snapper trophic position (¹⁵N enrichment) and an increase in benthic versus pelagic prey (³⁴S depletion) post spill. Results clearly indicate the DHOS affected red snapper diet and, potentially, prey resources. Study results also confirm the utility of stable isotope analysis to infer aspects of reef fish trophic ecology.