Penicillus capitatus: an algal island for macrocrustaceans

Abstract

Abundance and species richness of crustaceans associated with the calcareous green alga Penicillus capitatus in Puerto Rico increased with algal size. Faunal abundance was higher in the dry season than in the wet season, but species-area regressions were identical for the 2 periods. Faunal abundance rather than algal size, however, proved to be the best predictor of crustacean species richness on P. capitatus. Although there were no negative associations among species pairs, qualitative and quantitative changes in the crustacean assemblages during recolonization of defaunated P. capitatus and increasing dominance with animal density suggest the potential significance of differential immigration rates, displacement of certain taxa, and positive associations in explaining variation in species composition and species richness. Higher abundances of crustaceans (particularly amphipods and tanaidaceans) were found on P. capitatus than in the surrounding seagrass (Halodule wrightii) habitat; this is probably a function of protection from fish predators and habitat selectivity.