Classification and comparison of five estuaries in the southeast Gulf of California based on environmental variables and fish assemblages

Estuarine systems in subtropical and tropical areas of the Mexican Pacific are characterized by specific hydrological, biological, and anthropogenic conditions. Using multivariate analyses of geomorphic, biological, and anthropogenic variables, five of the largest estuarine systems of the southeastern Gulf of California were classified into estuary type using a similar classification method to that employed in New South Wales, Australia. Three estuary types were identified: tide-dominated, wave-dominated, and intermittently-closed. The characteristics of each estuary type were related to the fish assemblages from every system, using catch per unit effort to make results comparable among all estuaries. Our results demonstrated that intrinsic estuarine characteristics, such as geomorphologic, biological, physicochemical, anthropogenic, and biogeographical attributes, are likely to have a strong influence on the diversity and structure of fish assemblages, but more information is needed on the ecology and biology of the fish fauna to understand how these variables affect the different fish species.