Dominance hierarchies in xanthid crabs: Roles in resource-holding potential and field distributions

Abstract

We used laboratory experiments to determine the dominance hierarchy of 3 xanthid crabs occurring along the Louisiana Gulf of Mexico coast. Juveniles of the stone crab Menippe adina were dominant over adult Eurypanopeus depressus, which were in turn dominant over adult Panopeus simpsoni. The relationship of agonism to body size differed among species, with larger stone crabs initiating fewer behaviors of all types, while agonism was more frequent in medium-sized P. simpsoni and large E. depressus. Even when stone crabs were smaller than the other 2 species, they exibited similar levels of agonism, perhaps explaining how juvenile stone crabs can coexist with and grow through the size range of the 2 small xanthids before the emigrate from oyster reefs to pursue a solitary existence as adults. As predicted by game theory, for both food and shelter resources, dominance hierarchy predicted resource-holding potential (RHP). Stone crabs were more successful at acquiring and defending resources than P. simpsoni, and RHP for shelter was not reversed when stone crabs were smaller. A year-long field sampling study indicated that both M. adina and E. depressus were more common in subtidal habitats with shelter, while P. simpsoni was more abundant in an intertidal oyster reef and on a mud flat lacking shelter. We argue that these distributions could be explained by the lower ranking of P. simpsoni in the dominance hierarchy, and that behavioral interactions may thus play a role in shaping mud crab distributions, and deserve study of their role in explaining the distribution of other crabs as well. © Inter-Research 2005.