Aggressive Canadian Crabs Are Destroying Coastal Ecosystems

Posted: Sep 23 2018, 10:29am CDT | by , Updated: Sep 23 2018, 10:34am CDT, in Latest Science News


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Aggressive Canadian Crabs are Destroying Coastal Ecosystems
Credit: University of New England

Invasive crabs currently comprise only about 2 to 3 percent of green crabs in Maine.

A population of invasive green crabs from Canadian waters poses a serious threat to Maine's coastal ecosystems as they devour local soft-shell clams and damage underwater plants.

Green crabs are already notorious for their bad attitude. The ones that inhabit Maine waters also eat soft-shell and juvenile clams, but the new crab variant that came from Nova Scotia is even more nasty and angrier. They are voracious predators, raising concern for local marine life and shorelines.

"What we're seeing is this insane level of aggressiveness," said Markus Frederich, a professor at the University of New England in Australia. "They are the most aggressive crabs ever seen. We don’t understand yet why they are so aggressive.”

Canadian green crabs measure 4 to 5 inches across and has the ability to unsettle the overall balance of the marine ecosystem. Recently, researchers captured some crabs from Nova Scotia waters for the research. They are uncertain what physical and environmental factors drive their aggressive behavior.

"Any time I went down to grab one they went to grab me instead.” Louis Logan from University of New England said.

In the lab, researchers released two types of green crabs on a bed of eel grass in a saltwater pool and observed their behavior. There was a stark difference between local green crab and invasive species. Crabs from Nova Scotia badly damaged eelgrass beds that serve as habitat for many juvenile fish species.

“The crabs have a high potential for destroying soft-shell clams, eelgrass beds and who knows what else." Fredeich said.

These crabs currently comprise only about 2 to 3 percent of green crabs in Maine, but those numbers are expected to keep rising and their impact will be more visible in the future.

"It will be an entirely different ball game," said Fredeich. "It's just a question of when more of the crabs come and out-compete the Maine green crabs."

Invasive species are a major threat to many regions because they are difficult to get rid of once settle in new environments. Their impact is also difficult to predict but some invaders thrive to such an extent that they displace native species and severely damage local ecosystems.

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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