Notes on the population structure of the portunid crab Charybdis longicollis leene, parasitized by the rhizocephalan Heterosaccus dollfusi boschma, off the Mediterranean coast of Israel

The Levantine population of Charybdis longicollis. a Lessepsian migrant, has been parasitized recently by the sacculinid rhizocephalan, Heterosaccus dollfusi. Incidence of infestation, its effects on host's size, sex ratio and multiple infestation are examined, We recorded 77% infection rate with up to 57,6% of infested hosts bearing more than one extema. The rapid spread and the high prevalence of H. dollfusi can be ascribed to the dense population of the host and the year-round reproduction of the parasite promoting recurrent re-infection. As heavily-infested populations are presumably maintained by immigration, it is likely that the Levantine population of C. longicollis will suffer drastic perturbations, as it is doubtful whether immigration of non-infested crabs through the Suez Canal suffices for population renewal.