Decapod crustaceans associating with echinoids in Roatán, Honduras

Abstract

Echinoids comprise an integral component of coral reef ecosystems, providing trophic links, microhabitats, and refuge for a wide diversity of symbiotic organisms. We studied the association of at least eight species of decapod crustacean ectosymbionts with six species of echinoids at Roatán, Honduras, during 6–11 September 2015. Decapods associated most frequently with the echinoid Diadema antillarum (10.80% of individuals of this echinoid, six decapod species; n=799), followed by Eucidaris tribuloides (1.74%, three species; n=746), Echinometra lucunter (1.30%, six species; n=8349), Tripneustes ventricosus (0.86%, four species; n=1167), Echinometra viridis (0.23%, two species; n=862), and Lytechinus variegatus (0%, no species; n=12). Of 239 individual decapods observed, Percnon gibbesi was the most common species (48.5% of decapods, four echinoid species), followed by unidentified hermit crabs (Paguridae; 27.2%, five species), Stenorhynchus seticornis (11.7%, three species), Stenopus hispidus (6.3%, three species), Plagusia depressa (3.3%, three species), Panulirus argus (1.3%, one species), an unidentified small crab (possibly Pitho sp.; 1.3%, one species), and Mithrax verrucosus (0.4%, one species). The frequency of association varied with water depth for P. gibbesi, which associated more frequently with D. antillarum in shallow water (<5 m), and S. seticornis, which associated more frequently with D. antillarum in deep water (>5 m). None of the decapod species associated exclusively with echinoids or was specialized for associating with echinoids. Decapods associated with the longest-spined species, D. antillarum, at a rate more than six times higher than that of any other echinoid species, supporting the hypothesis that decapods seek shelter among the spines of echinoids to benefit from decreased predation.