Abstract

Natural banks represent the only naturally occurring hard-bottom structured habitat on the continental shelf in the Northwestern Gulf of Mexico and as such, may represent critical habitat for reef-associated fish species. However, the relative nursery values and functional roles of different natural bank types for reef fish in the Gulf are currently unknown. In 2009, we conducted monthly (May-Sept) visual surveys on SCUBA to quantify the density and diversity of reef fish recruits on two mid-shelf low coral diversity banks (Sonnier, Stetson) and two shelf-edge high coral diversity banks (East and West Flower Gardens). Overall fish density was highest at the two low diversity banks , and density, species richness (S), and Shannon diversity (H’) were significantly higher at Stetson than any of the other study sites. Analysis of similarities (ANOSIM) was used to compare fish assemblage structure among bank types, and pairwise comparisons showed significant differences in reef fish communities between low diversity and high diversity banks but no significant differences within a given bank type. Furthermore, significant differences in the densities of specific trophic guilds among study sites suggests that habitat partitioning may occur between bank types, particularly for upper-level trophic groups (i.e. piscivores, carnivores). Overall, preliminary analysis of the 2009 data suggests that both bank types support large and diverse communities of reef fish recruits and that high coral diversity and low coral diversity banks may support distinct fish assemblages and trophic community structures.

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