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NCC Magazine - Spring 2017


SPECIES PROFILE Eel-grass This unassuming species plays a major role in Canada’s coastal ecosystems MARTIN ALMQVIST/ALAMY/ALL CANADA PHOTOS. 12 SPRING 2017

Eel-grass, a type of seagrass, first evolved as an aquatic algae, moved to land and then returned to the ocean. Its long, bright-green blades resemble underwater ribbons. The plant’s complex root system allows it to anchor itself to the floors of shallow bays, coves, lagoons and estuaries. By filtering and trapping sediment, pollutants and nutrients, the species helps improve water quality. Eel-grass beds support many marine invertebrates and provide spawning and nursery habitat for numerous fish, resulting in important feeding areas for marine birds and mammals. STRUCTURE AND REPRODUCTION Often mistaken for seaweed, eel-grass differs from it in several ways. For example, unlike seaweed, eel-grass roots not only anchor the plants, they also absorb nutrients. Eel-grass also has flowers and veins. Eel-grasses reproduce in two ways: asexually, through cloning, and sexually, by producing seeds. Like land grasses, eel-grass shoots are interconnected through an underground rhizome (a large, root-like structure) network. As rhizomes spread, they create new shoots that are clones of one another. To reproduce sexually, male eel-grass flowers release pollen into the water, which is then moved by underwater currents. The pollen grains, which are the longest of any plant species in the world, then fertilize female flowers and produce seeds. A SENSITIVE SPECIES Eel-grass is highly susceptible to human interference. Shade from docks, floating log booms and algae also threaten this species. “Wasting disease,” caused by a marine slime mold, affects some Atlantic populations. A relatively recent threat to eel-grass is the European green crab — an invasive species that arrived in Atlantic Canada in the 1950s in the ballast water of ships — which cuts the grasses while digging in sediment for food. FACT SHEET SCIENTIFIC NAME Zostera marina SIZE AND WEIGHT Can reach lengths of up to 1 m. RANGE North America’s Atlantic and Pacific coasts, as well as Hudson Bay. POPULATION TREND Globally, eel-grass meadows have declined on average by about seven per cent per year since 1990. Some declines along Canada’s B.C. coast could have resulted from the introduction of the non-native Pacific oyster to the wild. In Newfoundland and Labrador, eel-grass abundance has increased over the past decade. STATUS IN CANADA No official status. NatureServe ranks it as imperilled in Ontario and Manitoba, and vulnerable in Quebec and Newfoundland and Labrador. DID YOU KNOW? Seagrasses are estimated to be responsible for 15 per cent of the total carbon storage in the ocean, even though they occupy only 0.2 per cent of the oceans. SCOTT LESLIE/MINDEN PICTURES. CONSERVATION EFFORTS The Nature Conservancy of Canada (NCC) is protecting eel-grass habitat along Canada’s Atlantic and Pacific coasts. In 2014, staff in Nova Scotia partnered with the Province of Nova Scotia and used aircraft and satellite imagery to map and monitor eel-grass beds in the Pugwash Estuary and Musquodoboit Harbour. The following year, NCC trapped European green crabs at the Pugwash Estuary to determine this invasive species’ population size. In addition, NCC has acquired valuable coastal land along Nova Scotia’s Northumberland Strait, which includes important eel-grass beds. NCC has also protected upland areas around estuaries in New Brunswick, such as those at Tabusintac, where research is being conducted on eel-grass. Meanwhile, in Quebec's Malbaie salt marsh, NCC has conserved a property that shelters an eel-grass colony. Black ducks make stopovers here during their migration, to feed on the plant. In British Columbia, NCC has helped restore eel-grass populations in the Campbell River Estuary on Baikie Island by replanting native vegetation in marshes along rivers and streams. NCC staff have also identified eel-grass beds as a priority habitat for coastal conservation projects, such as Grace Islet, Clayoquot Island and the Gullchucks Conservation Area.1 CRABBY TIME Green crabs are an invasive species that is now established in many locations in North America and is still expanding its range. Learn more at green-crab SPRING 2017 13