Port Mouton seagrass study to monitor underwater health

Port Mouton, N.S., has joined an international project that monitors the health of seagrass, and will deploy divers in its bay up to four times a year to investigate the state of its underwater vegetation.

Eelgrass, as it's known in Atlantic Canada, is considered a barometer of ecological health and is home to lobster, crab and small fish up and down the Nova Scotia coast.

But there are worldwide concerns that seagrass can be threatened by local pollution or sediment that spills into water from on-land operations.

"It's pretty much the canary in the coal mine in terms of estuary health," says Angela Douglas, executive director of the Southern Gulf of St. Lawrence Coalition on Sustainability.

The organization is helping set up four monitoring sites in Atlantic Canada. In addition to Port Mouton, a workshop has been held in Cornerbrook, N.L., while sessions are planned later this month for Malpeque Bay, P.E.I., and Tabusintac in northeast New Brunswick.

Community volunteers trained

The four locations join more than 120 sites around the world where seagrass is studied under the guidance of the Global Seagrass Monitoring Network. 

Last month, Fred Short, a University of New Hampshire marine scientist and director of the network, was in Port Mouton to train volunteers to properly set up a monitoring site.

Fifty-metre lines delineated by markers are established. Four times a year divers slip down to the bottom and place white squares at precise locations.

Photos are taken of the eelgrass at those spots and are then compared to prior samples to see if there are any changes in thickness or length.

"We look at water quality and other parameters to see what could be having an impact," Douglas says.

Trout farm a concern

A community group, Friends of Port Mouton, has been particularly concerned about a trout farm located in the bay. There have been prior eelgrass surveys in the area.

"We have found that eelgrass beds, when they're near a source of pollution, don't thrive. And those further away do," says Ruth Smith, a volunteer with Friends of Port Mouton.

Under the auspices of the Global Seagrass Monitoring Network, Port Mouton is setting up fresh monitoring zones following the standards set by the network. The first monitoring site is in the inner reaches of the bay. A second is being eyed for the Carters Beach area.

"When the eelgrass is under stress, the roots aren't healthy, the grass itself will be short and stubby and not thick and luxurious," Smith says.

Aside from pollution, seagrass can be harmed by harsh winters or even eaten by Canada Geese.