Habitat use and the effect of shrimp trawling on fish and invertebrate communities over the northern Gulf of Mexico continental shelf

The goals of this study were to characterize habitat-specific fish and invertebrate community structure over sand, shell-rubble, and natural reef substrata, and to assess the effects of trawling on the sand and shell-rubble habitats and their associated communities during quarterly trawl surveys over a 2-year period. Fish and invertebrate communities differed significantly among habitat types (analysis of similarities (ANOSIM); Global R ¼ 0.436, p , 0.001), and with respect to trawling exposure (ANOSIM; Global R ¼ 0.128, p , 0.001). Habitat characteristics were quantified from video transects sampled with a remotely operated vehicle, and included percentage coverage of tubeworms, bryozoans, anemones, corals, and algae, significantly affecting fish community structure. Diversity indices differed among habitats, with the highest Shannon diversity (H 0 ) and Pielou's evenness (J 0 ) over shell-rubble, specifically non-trawled shell-rubble. In addition, higher values of H 0 and J 0 were found over trawled sand relative to non-trawled sand habitats. Length frequency distributions of several abundant fish species showed truncated size distributions over trawled and non-trawled habitats and were both habitat- and species-specific. The study describes habitat-specific differences in community structure, highlighting the differences between trawled and non-trawled areas on the northern Gulf of Mexico continental shelf.