How a biologist is volunteering to track invasive species, monitor health of North Shore bays

Large areas of two bays in the P.E.I. community of North Shore are thriving, says biologist Sarah Stewart-Clark, but there are some areas of concern.

Stewart-Clark is a biology professor at Dalhousie University and grew up enjoying the beaches and bays around Tracadie, Covehead and Brackley. A few years ago she was named co-chair of the Sustainability of Bays Committee by the mayor of the North Shore.

As part of that volunteer position, Stewart-Clark has been making records of the ecological health of the area, above and below the water.

"I've spent, in this past week, about 25 hours snorkelling in Covehead Bay, taking video of different habitats," she told Island Morning host Laura Chapin.

"Documenting what is present and what problems there might be and where the healthy areas are, so that we can monitor from year to year what is normal for these bays "

Stewart-Clark said she has found some beautiful eelgrass meadows, crucial habitat for juvenile fish and crustaceansthatcan use it to hide from predators.

Invasive species

She has also been examining items along the surface of the water, such as channel buoys and wharfs, for evidence of invasive species.

The hope is to spot any that are trying to establish in the bays before they can become a problem. She is seeing signs that green crabs, an invasive species which first began to establish populations in eastern P.E.I., are having a negative impact on the bays.

"What I'm seeing is some evidence of eelgrass being uprooted by green crab," said Stewart-Clark, adding that is not the only threat the meadows are facing.

"I'm very concerned about the sea lettuce that is overgrowing the eelgrass because it can then block the sunlight from being able to reach sea grass. You know, there's really healthy spots and there's spots that are cause for concern."

Residential development problems

Sea lettuce can grow quickly when there are excess nutrients in the water, and in previous years agriculture has been cited as a source of these nutrients.

Buffer zones between farm fields and waterways have done a good job at mitigating that problem, said Stewart-Clark. A bigger concern for her now is residential development on the shore. This development can cause erosion, and any flow of land sediments into the bays can add nutrients into the water.

Stewart-Clark urged property owners not to remove trees from river banks and shores, because they help hold the banks together. She added people should do what they can to preserve marshland.

"In many communities, people want to build their home in one, but the marshes are actually really critical for our protection against coastal erosion," she said.

"So when a storm surge comes at Covehead, for example, it goes through a large marsh before it hits solid land. And a lot of the energy and the destructive forces of that storm surge are taken out as it travels through that marsh, so when it hits the cape, it's not getting the full brunt of it."

Stewart-Clark focused her attention on Brackley and Covehead bays this year, and hopes to have a look at Tracadie Bay in the future.

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