Interspecific Variation in Anemone Shrimp Distribution and Host Selection in the Florida Keys (USA): Implications for Marine Conservation

Host and symbiont abundances often depend on the degree of host specificity and differences in costs and benefits of these associations. In this study, we investigated the distribution of anemone shrimps and their hosts along with the shrimps' host selection behavior to evaluate the degree of host specificity in a nearshore benthic community undergoing rapid environmental change. We compared the distribution of two shrimp species, Periclimenes pedersoni Chace, 1958, and Periclimenes yucatanicus (Ives, 1891), with their three anemone hosts, Condylactis gigantea (Weinland, 1860), Stichodactyla helianthus (Ellis, 1767), and Bartholomea annulata (Lesueur, 1817). The proportion of host anemones occupied by each shrimp species was significantly non-random considering abundance of each species per location and significantly different from a previous study conducted 18 yrs earlier. This was due to a decline in S. helianthus abundance. Periclimenes yucatanicus abundance was correlated with C. gigantea abundance, but P. pedersoni abundance was correlated with B. annulata abundance and all anemone species combined. A dichotomous choice test between C. gigantea and B. annulata revealed that P. yucatanicus selected C. gigantea regardless of its original host species. However, P. pedersoni selected its original host species. These results suggest that P. yucatanicus retains a strong host specificity for C. gigantea, whereas P. pedersoni appears to show no particular host specificity. Species with strong host specificity, such as P. yucatanicus, may be less likely to switch host species, and therefore, may be more susceptible to a decline in host abundance.