Eelgrass: Humble Protector of our Fish and Shores

Guest Contribution by Emily LeGrand

If you’ve ever spared a thought about eelgrass, it’s probably been when you’ve been swimming in the ocean and some eelgrass tickled your belly and feet. You may have even thought something like, ‘I wish there was no eelgrass around, so I could see the bottom and stop feeling squeamish.’

But it is time to think again! Because eelgrass does so much more than just make swimmers uneasy.

Healthy eelgrass meadow

Healthy eelgrass meadow.

Considered a keystone species, eelgrass has many features that allow it to offer free, natural protection to some of Nova Scotia’s most unique and vital assets. And the fact that eelgrass is in decline across our coastlines is bad news for our small-scale fisheries, coastal property owners, and everyone who enjoys the benefits of coastal ecosystem health around our province.

Found along coastlines all over the world, eelgrass is a rare example of a flowering land plant that has evolved to survive underwater. The long, emerald green, flat leaves of eelgrass, which can grow up to a meter in length, billow in the waves along the coast in the sub-tidal and intertidal zones where it still gets enough light through the water column to photosynthesize. Their extensive root system anchors the eelgrass in place, while also locking in sediments and stored carbon.

Thick, waving eelgrass meadows provide vital nurseries for many of Atlantic Canada’s important fishery species. Juvenile groundfish, including haddock and cod hide between the fronds to find rest and protection from predators as they grow. Studies have shown that these young fish choose this habitat over open water if available, and that they do not cluster in schools as they do in open water, likely because they do not need the protection of the schooling behaviour. Young fish living in eelgrass meadows have also been found to grow bigger than fish of the same species that do not live in eelgrass.

Also unsung heroes of coastal erosion protection, dense eelgrass beds of work to slow and dissipate wave energy as it moves toward the land. Indeed, many studies show that a coastline stretch with a healthy eelgrass bed just offshore experiences slower erosion rates than neighbouring stretches with otherwise similar conditions.
Eelgrass beds also support cleaner coastal waters, as slowed water flow allows sediments contained in the water to settle out onto the bottom among the eelgrass’s thick root system. From here, suspension feeders – including periwinkles and sand dollars- that live around the roots of eelgrass can then filter these particles as they eat, vitally improving water quality, which in turn helps the plant get enough light.

There are notable eelgrass beds in many coastal areas around Nova Scotia, especially in estuaries, inlets and bays, such as Antigonish Harbour, Chedabucto Bay, Petpeswick, Cole Harbour, Musquodoboit Harbour, and Chezzetcook.

Frond of the humble but mighty eelgrass

Frond of the humble but mighty eelgrass.

Unfortunately, though,, most of Nova Scotia’s eelgrass beds are in a state of decline. For eelgrass to complete all of its good work, they need shallow, clear water to photosynthesize, and healthy, firm root systems to survive. But this humble and important plant is increasingly threatened by pollution-caused eutrophication, sedimentation, and invasive species.

Sewage effluent from coastal cottages, along with over-fertilized lawns and other managed landscapes can cause an increase in nutrients in coastal runoff. These nutrients allow algae to grow very quickly. As these algae die and decompose, this removes oxygen from the water. The algae also blocks sunlight from reaching the eelgrass, making it difficult for these sensitive plants to receive enough light to grow. When too much sediment erodes from coastal land, this also muddies the waters and limits the amount of sunlight reaching the eelgrass.

Another threat to eelgrass in Nova Scotia is the green crab, especially on the South Shore around Port Joli and Port Mouton. These crabs, introduced from areas of the Atlantic near Iceland in the 1980s, burrow deep in the mud of eelgrass beds, snipping the root systems as they dig. In some places, green crabs have completely decimated the eelgrass beds, leaving mud, young fish without food and protection, and shores and salt marshes exposed to the full impact of waves. Scientists and volunteers at Kejimkujik Seaside are trapping the green crab, mapping eelgrass beds so that we know what’s there and what we’re losing, and transplanting eelgrass to help it grow back. If you find yourself in that area this coming spring and summer, volunteering with these important initiatives is a great way to learn more, have some adventurous fun, and make a real impact on Nova Scotia’s coastal health.

So maybe eelgrass is a little icky to swim by. But if we can have a second thought, maybe it could be about doing our part to make sure eelgrass beds are healthy, so they can continue to help keep Nova Scotia’s coastal communities healthy too. On coastal properties, making sure sewage does not find its way to the ocean, using little or no lawn fertilizers, and covering bare soil with plants and plant material are all very effective ways to keep our coastal waters clean and clear for the eelgrass. And in turn, the eelgrass will offer a home for young fish to regenerate our economically important fisheries, and protect our shores from battering wave erosion.

Emily LeGrand coordinates the Living Shorelines project for the Ecology Action Centre’s coastal and water team, and is inspired by all the great work the humble, sensitive eelgrass meadows do for Nova Scotia.

To mark World Water Day (March 22nd, 2014), EAC is organizing Love Your Water Month. And if you love water, you’ve got to love eelgrass too! Click here for a glimpse of the water love-ins happening throughout March.

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5 thoughts on “Eelgrass: Humble Protector of our Fish and Shores

  1. these areas of eel grass also support soft shell clams, I’ve seen areas in the Joggins, Annapolis Basin, Digby, Nova Scotia when most clam beds had smothered out because of the sedimentation caused by the Annapolis tidal power dam project, one of the few clam beds left grew among the eel grass areas. we were digging as a depuration crew for Ford Fisheries…..the clammer.

    • Thanks Terry, for pointing out how soft shell clams also thrive in eelgrass beds! Great point. Pooling together our diverse perspectives to build awareness and appreciation for the fact that natural systems are so beneficial in ways that we don’t understand until we mess with them will hopefully bring us to a point of avoiding projects that create large, unintended changes like the Annapolis Tidal Power project in the first place. Please keep sharing your knowledge and observations of these patterns you see!

  2. I’m an eelgrass nut. For many years on Nantucket as a bay scalloper I fished a “Kinder-Gentler” scallop dredge. It has no chain bag, but instead netting and some plastic chaffing gear. The horsepower needed is much less, the scallop seed benefit I do believe, and the dredges fished well for me for many years. Fishing method is as important as gear design. I do love eelgrass cultivation and theory. I would say the eelgrass bed is one of earths greatest bio-engines. An old timer told me years ago that the eels would be quite thick in the beds, burrowing in like worms, aeration of the grass. Shellfish live to filter and filter to live. So a bay scallop produces dung, which feeds the grass, as it gets worked in by foragers, and as it enters into burrows. Eelgrass as it races to grow or out grow the epiphytes, produces great floating wrack lines at sea. If the water quality is bad the eelgrass can’t keep up with the epiphytes, or things that live on the grass. Accretion needs eelgrass. A thick pea soup of weed, in the boil, slows down the ability of waves to move sand. We could go on and on here.

    I wonder if the water temperatures in Nova Scotia would allow for our own bay scallop to be moved up there? Would this be worth the effort to try? You did have a species up there but it is now gone, one species of the four, so I’m told. Wellfleet and Provincetown Massachusetts have the bay scallops. Nantucket is having a good season, so I read in the papers. Prices to the fishermen are $15.00. I think that your article was excellent Emily. I have a TV show, “The Scannell Agenda”, and I talk up the importance of eelgrass and it being so important to the rebuilding, coastwise, of our bay scallop fisheries, which is one of my top projects. Eelgrass … Mother Natures nursery and womb. The scallop is the fruit of the eelgrass vine.

    Eco-system based fishery management can lend an economic hand to the improvement of the beds. Our systems are still now the archaic patronage based or limited entry based systems which must change if we are to excel at our jobs as cultivators and stewards of eelgrass and the rest, etc. etc. Friend me of Facebook if you would like to keep up with my projects. Thanks, Terrific Job Emily.

  3. Pingback: Living with the Shoreline | Small Scales

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