Growing grass in the sea: Why replanting eelgrass is so important for P.E.I.

The voracious appetite of the invasive green crab has taken its toll on the eelgrass in waters around eastern Prince Edward Island. Now a local environmental group is fighting back, by learning how to re-grow the seagrass.

Eelgrass is woven through oyster shells for replanting

Employees of the Souris and Area Branch of the PEI Wildlife Federation prepare the oyster shells to be used in planting the eelgrass. (Nancy Russell/CBC)

Eelgrass is disappearing in eastern P.E.I., in part because of nitrates mostly from the agricultural zone. When excess fertilizer gets in the water, it causes sea lettuce to grow rapidly and it smothers the eelgrass, which gets no light and dies.

Then there's the problem of the green crab.

Now a local environmental group is fighting back, by learning how to re-grow the seagrass.

The strands of eelgrass are woven into the oyster shells. (Nancy Russell/CBC)

"We started last year saying, can we transplant eelgrass and can we basically make a little garden plot and see if we can do it," explained Fred Cheverie, long-time coordinator of the Souris and Area Branch of the Wildlife Federation. 

Cheverie started by doing research and talking to people who've tried transplanting eel grass in other parts of Canada. They came up with a method that he describes as "fairly cheap and it works."

Oyster shells as anchors

In the fall of 2015, Cheverie and his crew decided to create a plot of eelgrass, 10 metres square, in the estuary of the Souris River. They waited until the water temperature dropped below 15 degrees, and then collected eelgrass shoots that washed ashore during a storm, storing them in a cooler filled with saltwater.

Next, they experimented with shells, looking for a way to anchor the eelgrass shoots to the ocean bottom. 

The oyster shells each contain several strands of eelgrass. (Nancy Russell/CBC)

Oyster shells, it turned out, worked best. Using an electric drill, they created half a dozen or so holes per oyster shell. 

"We took the eelgrass shoot and weaved it through the holes so that the root part would be in the bottom and the concave part was on top," said Cheverie.

"Then we simply go out in the area and we let it drop to the bottom in that area and what happens is the sand fills up in the little concave system  and it weighs it down and holds it there and that gives an opportunity for the little grass shoots to catch and start to grow."

Putting it to the test

The experiment worked, but Cheverie and his crew wanted to be sure.

"It worked out fantastically and we said, was that luck?" he explained.

"So we said let's go and try another 10 by 10 plot this year and see if we do it two years then we can go around and say we know how to plant eel grass and we know how to make it grow."

Planting the eelgrass is labour intensive. (Nancy Russell/CBC)

This year's eelgrass planting is in a different part of the Souris River, upstream from the estuary. But Cheverie is very aware that the experiment could still go wrong. 

"Our big fear and our big problem is if we go and put the eelgrass in an area where there are green crabs, we're kind of feeding them right?"

This year's planting is the first of the three year project. For this fall, the group has received $1,500 in funding from the Recreational Fisheries Conservation Partnership Program.

Future plans

Cheverie and his team will monitor both plots of eelgrass, in the hopes that they are landed on a formula that works.

"The idea is down the road, some day, we look at a place like Basin Head, which is a Marine Protected Area and is void of eelgrass due to the high green crab population, that we might be able to at some point restore that in the future."

The oyster shells are carefully dropped concave shape up so that sediment will cover it and help it to root. (Randy McAndrew/CBC)

In the meantime, Cheverie and his association continue to look for creative ways to get rid of the green crab, trying to stop it from taking an even bigger bite out of the local habitat.

About the Author

Nancy Russell has been a reporter with CBC since 1987, in Whitehorse, Winnipeg, Toronto and Charlottetown. When not on the job, she spends her time on the water or in the gym rowing, or walking her dog.