Comparing richness and abundance of cryptobenthic reef fishes in coral and rocky microhabitats in Bahía de los Ángeles, Gulf of California

Abstract

Rocky-coral ecosystems host highly heterogeneous habitats and functionally diverse fish communities. Within these systems, coral microhabitats play a pivotal role by offering a subset of the available resources to cryptofauna, particularly cryptobenthic reef fishes (CRF), which are notable for their abundance and diversity. This group of fishes, with adult lengths of less than 5 cm, shows highly specialized visual and behavioral camouflage, which often leads to their underrepresentation in studies. Due to the scarcity of research and the significant taxonomic complexity of CRF, this study investigated the association between CRF and the massive coral Porites panamensis in Bahía de los Ángeles, Gulf of California, and rocky substrate. We hypothesized that CRF densities would be higher in coral microhabitats because of their superior three-dimensional complexity. Two extractive sampling efforts were conducted in March and October 2022 (n = 16). A total of 238 individuals were collected, representing 14 species from 5 fish families. Five species accounted for 76.62% of the total abundance, with the families Gobiidae, Tripterygiidae, and Chaenopsidae being the most represented. The average density of CRF in P. panamensis microhabitats was twice that observed in rocky microhabitats (W = 46.5, P = 0.036). Moreover, CRF assemblage structure and composition differed significantly between microhabitats (Pseudo-F = 4.41, P = 0.004). These findings highlight the critical role of P. panamensis as a microhabitat and its influence on the benthic organization of CRF. Given the ongoing degradation of coral cover and the decline in structural habitat complexity, these results are essential to understand long-term shifts in cryptofaunal communities.