An Estuary Walk

Guest Post by Jocie Brooks

I am looking at Google Earth, following the coast south of Courtenay and I find myself staring at a river, the Trent, as it snakes down to the ocean, opening into a fan-like delta that forms a prominent bump on the coastline. Even from this bird’s eye view, I’m stuck by the estuary’s beauty—a geographic landmark that draws my attention away from highways and towns, compelling me to follow the undulating dips and curves of the natural coastline.

A few days later, I drive out to the Trent River on a sunny afternoon and find a trail that leads into the estuary. I walk through a meadow of winter-bleached grasses while saltmarsh mud sucks at my boots. Red-winged blackbirds and song sparrows are singing their spring songs and in an open patch of water on my right I can see the iridescent green heads of a flock of mallard ducks. Coming up over a berm of driftwood, the estuary is laid out before me and I am here at that magical place: where the river meets the sea.

Trent River Estuary
The Trent River estuary, just south of Courtenay, is a magical place for a short nature walk.

The river mouth is dotted with hundreds of gulls, looking brilliantly white in the sunlight, and dozens of American widgeon and green-winged teal dabble near the shore. A bald eagle soars over, and the birds all rise in a whirling commotion; a few minutes later they have settled back down again. I imagine that these cycles of drama and calm play out several times a day, with the arrival and departure of each large bird-of-prey. I look across directly to Comox and the water is a cold indigo blue. To my left is the Courtenay River estuary, one of the largest and most significant estuaries on Vancouver Island, which actually encompasses this smaller estuary. I am on an estuary within an estuary.

Enjoying a moment of solitude—there isn’t anyone else here today—I sit on the beach and think about estuaries. Most of our towns are situated on estuaries: the Campbell River, Courtenay River, Big Qualicum River, Englishman River (Parksville), Nanaimo River and Cowichan River to name a few. Rivers and estuaries are of central importance to our human communities, and have been for thousands of years. The attraction of estuaries is something that humans share with other creatures too; at least 80% of all coastal wildlife depends upon estuaries for part of its life cycle, even though estuaries take up only a tiny fraction of the coastal land base.

The word estuary comes from the Latin word aestuarium, meaning a tidal inlet of the sea. The root aestus means undulating or boiling, and refers to things in a state of flux—such as the heat of fire, or the comings and goings of tides. Estuaries are highly dynamic: erosion, flooding, tides and wave action are constantly changing them. A continuous mixing of fresh water and salt water creates an extraordinarily rich and complex ecosystem, considered by many to be among the most productive ecosystems on earth.

I continue my walk now, along the edge of the estuary. I hear the cry of a killdeer and see a flash of a wing from the grass. I realize that this land I walk on—the ‘bump’ on the map—has been accreted as sediments wash down from the river over a long period of time. These sediments are being continually deposited, forming a slope that extends out into the ocean. The estuary is fertilized by these river sediments, which are held in place by vegetation on land and in water.

Below the tide line, there are often extensive eelgrass beds. Eelgrass, a flowering plant with shiny green strap-like leaves, grows from a network of rhizomes (underground stems) that stabilize sediments and slow wave and tidal action. Eelgrass beds are lush underwater meadows that provide food and shelter to thousands of organisms. At the bottom of the food chain are billions of microorganisms: bacteria, diatoms and algae that are in turn grazed upon by snails, sea slugs, limpets and other creatures. All species of juvenile salmon are protected and nurtured in the estuary before they venture out to the open ocean. When the herring spawn in the spring, eelgrass is coated with their roe.

With such an abundance of food, estuaries are a major destination for migrating and over-wintering birds, attracting as many as five million birds each year along BC’s coast. Mammals are drawn to the estuary also: black bears, grizzlies, harbour seals, river otters, sea lions, raccoons, mink and of course humans.

Aldo Leopold, in his landmark book Sand County Almanac, states: “Man always kills the thing he loves…” Living in close proximity to coastal estuaries, humans have routinely altered or destroyed these habitats. The statistics are disheartening. Globally, in the past 60 years alone, one-third of all estuary lands have been destroyed, and coastal wetlands are disappearing four times faster than the rate of rainforest deforestation. Here in BC, estuaries have been routinely dredged, diked, drained and filled or reclaimed for agriculture or development. Everything eventually ends up at the estuary—be it muddied waters from deforestation, agricultural pollutants or industrial run-off. Garbage is often dumped into estuaries; it isn’t uncommon to see a rusted shopping cart or the hulk of an abandoned car. Even greater threats loom—the possibility of an oil spill that could contaminate an estuary indefinitely.

My walk seems to be ending on a gloomy note, so before I head to the car I take a side trip to the rocky bank of the river, and watch a slate-blue belted kingfisher swooping gracefully along the wooded edge opposite. Despite all of the threats to this sensitive habitat, the kingfisher and all of the other birds I’ve seen today still suggest that the estuary is a place of richness.

Scientists are now discovering that estuaries are more significant and beneficial than we ever could have imagined. Sediments stabilized by estuary vegetation trap and store immense amounts of carbon. Called “blue carbon,” this estuarine carbon far exceeds “green carbon,” or carbon that is fixed and stored by forests. Estuary sediments are also valuable detoxifiers, filtering and purifying water. The tide continually washes in nutrients, and flushes out wastes. If any place can suggest hope, it is the estuary.

In BC, efforts are now being made to restore estuaries and their vegetation, especially eelgrass beds. Many local organizations (too many to list here) run mostly by volunteers have taken a lead in restoring, preserving, and raising awareness about these precious places. Estuaries have been, and always will be at the heart of our coastal communities; every time I visit an estuary as I did today, and witness all of the life there, it reaffirms this simple truth.

Getting There:

On the old Island Highway 19A drive south from Courtenay through Royston. Look for Carey Place on the left hand side of the road just before the Trent River bridge. Drive to the end of the short road and park. Rubber boots recommended, ideally you should explore at low tide.

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