"About one in four hosts were parasitized. "The infection rates on Calvert Island were higher than I would've anticipated," Whalen said. But when a parasite is introduced from elsewhere, that armistice may never arrive. After all, the parasite needs a host to survive, and killing it off at once would not make a great long-term strategy. When a parasite coevolves in the same place as its host, they often reach a sort of détente, Paulay said. The shrimp's presence affects how the entire mudflat ecosystem functions-or doesn't. They cycle nutrients when they filter food, pumping oxygenated water into an expansive network of tunnel dwellings, which provide housing for a suite of creatures, including gobies, worms, clams and other shrimp species. Mud shrimp may not be much to look at-much like crayfish with stumpier claws-but these homely crustaceans play an outsized role as environmental engineers in the mudflats of the Pacific Coast. The record represents a northward leap of more than 180 miles from its last known northern boundary. The parasite was found at Calvert Island in a 2017 survey of marine life. Their appearance at Calvert Island, 150 miles from the nearest city of more than 5,000 people, shows "clearly, they can do it on their own," said study co-author Gustav Paulay, curator of invertebrate zoology at the Florida Museum of Natural History. griffenisis thought to have first arrived in North America by traveling in ships' ballast water. Most scientists believed the parasites' expansion was exclusively mediated by human transport-O. "But this particular parasite wasn't initially on my radar." "I was on the lookout for things that seemed out of place," said study lead author Matt Whalen, a Hakai postdoctoral researcher at the University of British Columbia who studies coastal biodiversity. Scientists found the parasite during a 2017 bioblitz, organized by the Hakai Institute and the Smithsonian Institution's Marine Global Earth Observatory, in which they intensely surveyed and documented marine life. griffenis at Calvert Island, described in a new study, represents a northward leap of more than 180 miles. By the 2000s, it had reached as far as Vancouver Island. Orthione griffenis, a cough drop-sized crustacean native to Asia and Russia, has decimated mud shrimp populations in California and Washington over the past 30 years, causing the collapse of delicate mudflat ecosystems anchored by the shrimp.
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