Parasite Communities of the Pacific Mole Crab, Emerita rathbunae (Anomura: Hippidae), in Sandy Beaches from Guerrero and Michoacán, Mexico

The species composition and infection levels were determined for helminth parasites in the mole crab, Emerita rathbunae, collected from seven sandy beaches from Guerrero and Michoacán, México. A total of 494 crabs were collected between August and December of 2009. The number of crabs that were examined from each beach varied from 40 in Lázaro Cárdenas to 114 in El Revolcadero. The cephalothorax length varied significantly between the sampled beaches, from 32.9 ± 5.5 mm (Ixtapa) to 40.5 ± 1.7 mm (Las Trancas). Four species of larval parasites were identified: 1 metacercaria (Microphallus nicolli), 1 cystacanth (Profilicollis sp.), 1 cestode (Trypanorhyncha) and 1 nematode (Proleptus sp.). Infection levels (prevalence and mean abundance) varied significantly between beaches, due to possible differences in the availability of final or intermediate hosts in beaches visited by tourist and those beaches not visited by tourists, as well as the size of individual hosts. Helminth communities, at levels of component and infracommunity, were characterized by a low number of species (3 to 4) and a high dominance by the metacercaria of M. nicolli. The body size of the hosts was positively correlated with the number of parasites and species richness of helminths, indicating that larger crabs accumulate a higher number of parasites during the lifetime, and that they harbor a higher number of species of helminth than smaller crabs. J. Violante-Gonzalez et al.