In 1964 an introduced parasite, Loxothylacus panopaei, was discovered in Chesapeake Bay. The female parasite infects recently molted crabs by burying into the carapace and preventing the crab from reproducing. Once inside the crab, she forms a sac protruding from the crab’s abdomen where several broods of thousands of larvae each are produced. Parasite prevalence in populations of the White-fingered Mud Crab, Rhithropanopeus harrisii, has been monitored by Smithsonian Environmental Research Center (SERC) researchers for many years. With these long-term data we hope to learn why the parasites are abundant some years but nearly absent in others. Starting in 2011 we conducted focused experiments to determine how different life cycle stages of this parasite are influenced by salinity and temperature and how each of these factors affects the populations of White-fingered Mud Crab.
The protruding sacs, indicated by the arrow, of the Loxothylacus panopaei parasite inside the White-fingered Mud Crab, Rhithropanopeus harrisii
Hines, A.H, F. Alvarez, and S.A. Reed. 1997. Introduced and native populations of a marine parasitic castrator: variation in prevalence of the Rhizocephalan Loxothylacus panopaei in xanthid crabs. Bull Mar Sci, 61(2): 197-214.
Grosholz, E.D. and G.M. Ruiz. 1995. The influence of spatial distribution and genetic variation on castration of the xanthid crab Rhithropanopeus harrisii (Gould) by an introduced parasite. J Exp Mar Biol Ecol 187: 129-214.