Contribution of cryptobenthic fishes to estimating community dynamics of sub-tropical reefs

Small, cryptic (cryptobenthic) fishes are an under-surveyed component of reef fish assemblages that can account for a significant amount of diversity, function, and structure of reef fish communities. A complete picture of reef fish dynamics requires an accounting of these species and inclusion of them in analyses of community ecology. We report the results of a large-scale, quantitative study of the rocky reef fish community in the Gulf of California (GOC), where we collected cryptobenthic fishes and surveyed conspicuous fishes to calculate species richness, density, biomass, and community metabolism of the entire fish assemblage. We catalogued 20 764 individuals, representing 112 species in 36 families. Cryptobenthic fishes accounted for more than 40% on average of the species richness per site but were generally unobserved during visual surveys. They also accounted for more than 95% of the total fish abundance and up to 56% of the fish community metabolic requirement, both a likely result of their small body size. The relative contribution of cryptobenthic fishes to the entire quantitatively sampled assemblage differed between the northern and southern GOC, with the north being relatively 'more cryptobenthic' than the south. This study is the first to combine quantitative surveys and collections of the entire fish assemblage in the GOC and is one of the most extensive of its kind for any ocean basin, to date. Our results demonstrate the importance of quantifying all size classes and all functional groups when studying the ecology of diverse vertebrate communities.