The role of habitat selection on the diversity of macrobenthic communities in three gulfs of the Cuban Archipelago

Diversity and faunal composition of macrobenthic communities remain poorly known in the Caribbean Sea. Here, we explore the diversity and abundance of marine macrobenthos across three gulfs of the Cuban Archipelago and examine the role of habitat type in determining faunal composition and function. Samples collected from 32 soft-bottom sites across four habitat types (mangroves, seagrass beds, unvegetated mud bottoms, and coral reefs) yielded 4231 individuals representing 22 higher macrobenthic taxa. The most abundant taxa were polychaetes, nematodes, crustaceans, and mollusks. Mollusk fauna was particularly diverse (105 species and 74 genera) despite being dominated by two taxa: a bivalve (Parvilucina sp.) and gastropods (Caecum spp). Habitat type was weakly interrelated with the faunal composition of the entire macrobenthos and its molluscan component (<20% of explained variance, in both cases). This weak correlation might reflect the influence of within-habitat heterogeneity, ecological drift, or dispersal barriers. Functional traits differed among habitats, with infaunal mollusks typically found in mud bottom and carnivores more abundant in mangroves. The regional mollusk species richness (105 species) exceeded the richness observed within individual gulfs (39, 40, and 59 species), highlighting high regional diversity. Anthropogenic factors could also be at play. The results suggest, tentatively, that fisheries might have affected the functional and taxonomic structuring of the sampled macrobenthic communities. This initial survey suggests that habitat selection does not exert a strong effect on the macrobenthos (or its molluscan component), and other assembly processes such as drift, dispersal, and human impacts may be important.