Canadian green crabs are posing a serious threat to the ecosystem by eating soft-shell clams and destroying native eelgrass, according to research.
The crustaceans which hail from Nova Scotia, but are originally from northern Europe, are more aggressive and destructive than its close relative, which is found in the waters off Maine in the United States.
“What we’re seeing is this insane level of aggressiveness,” Markus Frederich, a professor at the University of New England, noted.
The professor pointed out that the crabs are genetically distinct because they are hardier and adapt more easily to colder water than their Maine-based relative, but belong to the same species.
“It will be an entirely different ball game,” Frederich remarked, explaining “it’s just a question of when more of the crabs come and out-compete the Maine green crabs. We can't do anything about it," Frederich added. "The only thing that we can do is learn how to live with it."
The aggressive newcomer currently comprises only about 2 to 3 percent of Maine’s green crab population, which will likely change as they migrate to the south.
Researchers, who conducted a soon-to-be-published study, monitored 200 green crabs from Canada with hopes to determine if a particular gene or hybrid vigor is responsible for the crustacean’s aggressiveness.
Hybrid vigor theorizes that crabs could be more aggressive as they establish themselves, but become more mellow later on.
The Canadian green crabs first entered the United States in the 1800s and depleted the soft-shell clam population before moving to Nova Scotia.