Biological inventory and latitudinal gradient of the rocky and reef associated fish along the southern Mexican Pacific

Shallow water reef fishes of Guerrero and Oaxaca (Mexico) were studied through visual censuses as part of exhaustive biological inventories conducted from 2004 to 2019. The systematic checklist comprises 183 species from 55 families. The most representative families were Serranidae (14 species), Carangidae (13), Muraenidae, and Labridae (11 each). The highest representativeness at the zone level was obtained at Ixtapa-Zihuatanejo (158 species), Huatulco (141), Acapulco (121), Puerto Ángel (62), and Puerto Escondido (39). Sample-based rarefactions showed that the biological inventory at the regional level has a representativeness of 90.51%. The PERMANOVA results showed that the fish assemblage differs among zones, while the SIMPER analysis showed that the variability is a product of the species dissimilarity among zones, mainly among the cryptobenthic, highly mobile, and seasonal species. The average taxonomic distinctiveness (Δ+) shows that Ixtapa-Zihuatanejo has greater taxonomic diversity, followed by Acapulco and Huatulco with intermediate Δ+ values, while Puerto Escondido and Puerto Ángel have the lowest Δ+. Overall beta diversity (βSOR) was mostly due to nestedness (βSNE = 0.167) rather than spatial turnover (βSIM = 0.365), while pairwise turnover species (βsim) was high between Ixtapa-Zihuatanejo vs. Puerto Escondido and Huatulco vs. Puerto Angel. This study outlines new knowledge regarding how the mosaic of rocky and reef associated fish is shaped along the reefs and rocky-reef patches in the south of Mexico.