ECU Scientists Track Spread Of Zombie Crabs

Aug 4, 2016

Researchers at East Carolina University are studying a parasite that can take over the reproductive systems of mud crabs.
Credit Cliff Hollis, ECU News Services

North Carolina's mud crabs are falling victim to an invasive parasite that researchers say turns them into walking zombies.

April Blakeslee is an assistant professor of biology at East Carolina University. She said the parasitic barnacle called Loxothylacus panopaei, or simply Loxo, can commandeer the reproductive systems of the crabs and alter their behavior.

"This parasite kind of takes over the whole host," said Blakeslee. "It takes over its ability to reproduce, it affects its behavior, it essentially just becomes this vessel for the parasite."

Once the barnacle has colonized the host, it tricks the crab into raising more parasites.

"When the parasite takes over, it actually produces a larval sac on the abdomen of the crab, and that larval sac is then cared for by the crabs, as if it were their own brood," said Blakeslee.

Researchers believe the barnacle spread from the Gulf of Mexico up to the Chesapeake Bay along with oyster shells.

Dr. Blakeslee and graduate student Christopher Moore deploying a crab collector unit, or crab condo, at Goose Creek State Park.
Credit Cliff Hollis, ECU News Services

Blakeslee and a team of researchers are conducting a year-long survey to monitor crab populations in the Pamlico and Neuse River systems. She hopes to measure how far Loxo has spread in North Carolina, and what conditions it thrives in.

Because the parasite isn't native to the region, crabs here have little natural protection, Blakeslee said. If too many fall victim to the barnacle, it could drive down their population numbers.

"They castrate their host crab, so they essentially remove any ability for the crab to be able to reproduce," said Blakeslee. "So that of course is really problematic for the crab, because if it can't reproduce, then it’s going to affect their population numbers."

She noted mud crabs occupy a key role in the food chain, providing a food source for many species. She said if the population dwindles significantly, it could destabilize the coastal ecosystem.