Latitudinal variation in structure and function of conspicuous reef fish assemblages along the western Gulf of California

Abstract

The Gulf of California is characterized by great biodiversity, high biological productivity and important fisheries. Studies on community structure of the reef fish fauna in the region have been conducted mainly in central and southern areas and, except for a few studies that have focused on cryptic species, there are no comparisons of the fish assemblages along this 1,600 km sea. In this study, we examine how diversity and community structure of rocky reef fishes vary with the latitude in the north, central and southern part of the west side of the Gulf of California. We conducted stationary visual censuses in observation cylinders (5 m radius) in 6 locations between Bahia de los Angeles (29° N) and Los Cabos (22° N) and estimated the following ecological descriptors and indexes: species richness, abundance, Shannon diversity, Pielou evenness, average taxonomic distinctness, and average trophic level. In addition, we used ordination analysis to determine the degree of similarity among study areas. Our results identified 3 distinct zones: north (29° N), central (27° N to 24° N) and south (24° N to 22° N).