By the Bay: The importance of salt marshes
Where ocean meets the shore, rubbery-textured, salt-tolerant plants grow in abundance. Sea asparagus spreads across the mud, interspersed with clumps of pink-flowered sea rocket. Goosefoot, recognized by the shape of its leaves, sprouts along the tide limit.
In summer, orange tendrils of salt-marsh dodder sprawl over the marsh, as if someone had sprayed luminous paint. Salt marshes are deceptive: the rubbery plants and black mud, full of decaying matter, combine to be among the most productive habitats in the world.
Northern pintails gather to feed in salt marshes by the thousands, pushing their elegant necks and heads into the wet mud to get at seeds and small crustaceans.
These attractive ducks nest in the Prairies and fly to the coast for winter, where they join flocks of other dabbling ducks, such as mallard, American wigeon and fast-flying, green-winged teal. Brant, small dark geese from the high Arctic, forage further offshore, where eelgrass grows.
Above the tide line, Townsend’s voles and other rodents build nests of grass and burrow through the rank vegetation to stay hidden from predators overhead.
Voles are a favourite prey of northern harriers, short-eared owls, rough-legged and red-tailed hawks, and also snowy owls. These huge, white, Arctic-nesting owls are currently visiting the Boundary Bay salt marsh for a second consecutive winter. Rodents are not their only prey, and snowies will eat small waterbirds, such as bufflehead and horned grebe.
The presence of abundant food in the Boundary Bay salt marsh is a major reason why so many birds of prey are drawn here, making it Canada’s number one location for number and diversity of wintering raptors.
The productivity and ecological importance of salt marshes took a long time to be recognized, and even today, they are often disregarded.
People smell the mud, look at the brown grass, and see little on the surface. Yet this habitat is a nursery for so many species that power the food chain. Microscopic plankton feed larvae, crabs, worms, and shrimp, that grow to feed forage fish and birds, salmon, porpoises and whales.
Completely different types of marshland prevail at the mouth of the Fraser, where the freshwater influence is strong. When the Fraser delta was historically dyked and drained, only the shores of Boundary Bay retained a moderately large stretch of salt marsh.
Because their value often goes unrecognized, salt marshes remain in our landscape almost as an afterthought.
Anne Murray is a local naturalist and author of A Nature Guide to Boundary Bay and Tracing Our Past ~ A Heritage Guide to Boundary Bay, see www.natureguidesbc.com. Anne blogs at www.natureguidesbc.wordpress.com.