Decapod crustaceans associating with echinoids in Roatán, Honduras

Abstract

Echinoids comprise an integral component of coral reef ecosystems, pro- viding trophic links, microhabitats, and refuge for a wide diversity of symbiotic or- ganisms. We studied the association of at least eight species of decapod crustacean ectosymbionts with six species of echinoids at Roatán, Honduras, during 6–11 Sep- tember 2015. Decapods associated most frequently with the echinoid Diadema antil- larum (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), Echi- nometra viridis (0.23%, two species; n＝862), and Lytechinus variegatus (0%, no spe- cies; 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 spe- cies), 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 frequent- ly 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.