Students research options to protect clams from crabs

YARMOUTH, Maine (NEWS CENTER) -- Most of the students at Frank H. Harrison Middle School in Yarmouth, a town which hosts an annual clam festival, didn't know that the coast of Maine was under siege by an invasive crab that has been decimating clam populations until they started researching ways to combat the crabs.

Last fall, students in Mr. Cuthbert's 7th grade class were challenged to come up with a problem to solve, and chose to explore the issue. For their efforts, they were honored by Samsung as one of fifteen finalists nationwide in the company's Solve for Tomorrow Science and Technology Competition. But the real prize in their eyes is finding a solution that will help clams, and clammers, survive.

In June, the students, with the help of Dr. Brian Beal, a professor at the University of Maine Machais, put a small experiment in place in Pogey Cove. There, they planted small plant pots into the ocean floor at low tide. Each pot contained 12 juvenile clams. Some of the pots were covered with a flexible mesh, others were protected with a more rigid wire screen, and another plot was left unprotected.

Today, more than four months later, the pots were pulled and the results recorded to see what, if anything, were effective in protecting the clams from the European Green Crab.

"And the answer isn't very good," stated Dr. Beal. "If we don't have any protection at all, there isn't one clam that survived."

Students carefully took each experimental pot and removed any netting before spraying the mud, clams and crabs with hoses, sifting away the muck to see what each pot contained.

"So 33% of them survived in this particular experiment," said Beal as he showed off two healthy looking clams. But unfortunately, that result was not a common one.

"I'm seeing death and destruction," he said.

Students picked through the remains, closely examining each tiny clam shell, looking for chips along the ridges which are a tell-tale sign of a hungry crab prying open the shell in search of a meal.

"The ones with the hard tops certainly keep the green crabs out the most," said student, Ben Cox-Faxon.

He, like many of his classmates, was surprised at how few clams made it.

"I was thinking a little higher, but certainly not this low of a survival rate," he said. "It was stunning to see how many dead clams there were."

The clams were not only ravaged by the crabs, but by the milky-ribbon worm, a native predator that showed up in many of the experimental pots as well.

"So when you combine the milky-ribbon worm and the green crab, the answer is not very good survival for the soft-shell clam," explained Beal.

Less than 10% of the clams survived, but there was a glimmer of hope scattered among the shattered shells, hundreds of tiny, native clams were also found growing in the pots, a sign that with some help, the clam population could rebound. The hope is scientists, young and old, can find an answer soon.


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