60.2 Saturday, Jan. 5 Predation and parasitism: It's not all bad news GEHMAN, AM; University of Georgia email@example.com
There are multiple theoretical studies predicting the outcome of the addition of predators in host-parasite systems. In a direct developing and castrating system, high levels of predation on infected individuals will likely lead to a reduction in parasite infections, but empirical data is currently lacking. The Rhizocephalan barnacle parasite Loxothylacus panopaei provides an ideal system for investigating parasite response to predation. L. panopaei is invasive from the Chesapeake Bay to Florida and infects the mud crab Eurypanopeus depressus. It has been hypothesized that E. depressus maintains a small size because it is able to escape predation by hiding in the interstitial space between oyster shells. E. depressus with adult L. panopaei infections carry a large externa, the external reproductive organ of the parasite, which increases the crabs size and could decrease mobility. I investigated whether infected mud crabs were more susceptible to predation by the native blue crab Callinectes sapidus than their healthy counterparts. In all treatments infected crabs were consumed at higher rates then healthy crabs, with some predators exclusively consuming infected crabs. On average, infected crabs were consumed three times as often as healthy crabs. With predators selectively feeding on infected hosts the parasite populations could be driven to extinction. In this system, a native predator may be helping to protect the native crab species from its invasive enemies.