Underwater Gardening

February-March 2006

This is an article from WaveLength Magazine, available in print in North America and globally on the web.
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by Ann Archibald and Ramona C. de Graaf

Eelgrass beds are among the richest marine nurseries on the coast. Ramona C. de Graaf photo.

As we paddle out in the early morning at low tide for the first eelgrass survey, the calm waters of the Cowichan estuary and the waving eelgrass beds draw us into a liquid dimension. Overhead, ospreys hunt their morning prey and the rising mist slightly obscures the estuary’s northern shore. We are paddling to the intertidal flats to see if we can find any eelgrass on the north shore of the estuary, an area with a long industrial past, now mainly empty mudflats where once an emerald meadow teemed with life.

Located on the east coast of Vancouver Island, approximately 50 kilometers north of Victoria, and formed by the confluence of the Cowichan and Koksilah Rivers, this estuary is one of the largest in BC. A visitor here can find a rich history in this traditional territory of the Quw’utsun’ (Cowichan) people.

The Cowichan estuary once boasted extensive meadows of eelgrass habitat and provided an abundant source of shellfish, herring and salmon. Quw’utsun’ elders and long-term residents tell of a vibrant, healthy ecosystem. Octopus hunted in the eelgrass, basking sharks were frequently seen and crabs were so plentiful that it took mere moments to round up dinner. Much has been lost over the intervening years due to agricultural dyking in the intertidal zone and log booming in the tidal flats.

Muscular moon snail at work. Michele Deakin photo.

Although now a working harbor, it’s still a vast wetland and intertidal wildlife area. With over 200 resident bird species and thousands of overwintering waterfowl, the Cowichan estuary still provides critical habitat for many species such as the brant goose, brown pelican, river otter and snowy plover. Paddlers can often find California sea lions and Harbour seals hauled out on the log booms.

You may not think of the Cowichan as a paddling destination, but think again! Environmental groups, government agencies, businesses and residents have long been working to increase natural habitat in the Cowichan estuary and protection is now in place to limit industrial impacts. The Nature Trust and Ducks Unlimited, working closely with industry and environmental agencies, have successfully acquired over 300 hectares of key intertidal wetland for protection and restoration. These conservation efforts over the past twenty years have steadily improved habitat quality for waterfowl and marine life, and further restoration plans are now underway on eelgrass.

The Cowichan Community Land Trust (CCLT) is working with community groups and landowners to encourage and support community stewardship of the natural heritage. Part of that work included hosting a workshop about eelgrass by the Seagrass Conservation Working Group (SCWG), a consortium of many groups involved in mapping and restoring eelgrass in coastal communities throughout BC.

Volunteers prepare for eelgrass replanting. Cowichan Community Land Trust photo.

The workshop resulted in a community commitment to increase eelgrass meadows in order to restore the food web on the northern shore. Last summer, restoration work, or ‘underwater gardening’, was done to transplant eelgrass to these north shore sites. Participants used kayaks, canoes and dinghies, along with a hand-held GPS, to survey existing eelgrass beds during low tides. Watercraft such as these were important to the work because they can maneuver in the mudflats at very low tides without damaging existing eelgrass beds. The first test transplant saw over 400 eelgrass shoots planted in four test sites on the estuary’s northern shore. Immediately after the test plot of eelgrass was planted, fish moved into these small patches of 100 shoots each.

Monitoring the density and growth of the new transplants will be necessary to ensure the shoots are taking hold, and to determine whether there are any unforeseen impacts that may prevent these transplants from establishing. Test sites that thrive will clear the way for a larger transplant of thousands of eelgrass shoots in the spring of 2006, providing a critical mass for reestablishing an eelgrass meadow on the northern shore.

Cowichan Bay Kayak & Paddlesports in Cowichan Bay Village has information on eelgrass and the transplanting process as well as laminated maps of the transplant sites. Dedicated paddlers can even borrow a hand-held GPS unit, to mark the beds or inventory the wildlife spotted as they glide over emerald eelgrass among seals, cormorants, kingfishers and the mighty salmon.

WANT A SEASIDE ADVENTURE?

Start at the shoreline edge and watch for the majestic blue heron spearing fish as it hunts within the protective cloak of this lush meadow. Now, push off from the beach and look below as you glide by for a glimpse of a unique food factory teeming with life.

In spring, the blades are heavy with herring eggs deposited by spawning adults. These eggs are fuel for crabs, seabirds and mammals, from killer whales to humpbacks to humans. Herring is a critical part of a healthy ocean, and eelgrass is essential to the recovery of the once-abundant herring to our coast.

In May and June, look for thousands of fingernail-sized dungeness and red rock crabs as they hide under the eelgrass rhizomes and feed on the thick plankton soup captured by the wave-calming blades of this incredible aquatic plant.

By slowing down water currents, the eelgrass beds capture the rich Cowichan/ Koksilah river deposits and stabilize shoreline and beach areas. The beds vibrate with life, including perch, sticklebacks and sculpins—a perfect hunting ground for juvenile ling cod. Juvenile rockfish seek refuge in this emerald nursery until they grow big enough to outwit their predators.

A number of species have taken to mimicking the eelgrass blades, including the eelgrass nudibranch (sea slug) and the northern bay pipefish. The pipefish body has transformed itself to look like an eelgrass blade, blending into its home, hovering within the plants, using its chameleon-like eyes to pounce on its prey with its vacuum cleaner-like snout. The pipefish is the evolutionary granddaddy of the seahorse. Yes, our own seahorse right at your doorstep! Males have a kangaroolike pouch filled with hundreds of eggs left by females, and give birth to several broods each year. Bay pipefish, like the eelgrass limpet and eelgrass nudibranch, are found in no other habitat and need these meadows to survive. Jelly fish, nudibranchs, sand dollars, moon snails, mud shrimp and clams are also at home within the Cowichan estuary.

Eelgrass is not a seaweed and must have good, clean water and plenty of light, so eelgrass beds are rapidly disappearing as shoreline development and land-based run-off cloud the water, killing the plant. We need to protect these fragile nurseries, home to the many birds, invertebrates and fish that help to make the water’s edge such a wonderful part of our island life-style and local economy.

Expertise on eelgrass restoration methodology was contributed by Cynthia Durance and Nikki Wright of the Seagrass Conservation Working Group. Eelgrass information can be found at www.stewardshipcentre.bc.ca/eelgrass/index.html. Funding for this work has been gratefully received from the Pacific Salmon Commission and the Habitat Conservation Trust Fund. For those interested in finding out more, or participating in this project, contact the Cowichan Community Land Trust Society cclt@island.net or drop by Cowichan Bay Kayak & Paddlesports in Cowichan Bay Village for kayak tours of the area, rentals, lessons and sales: 1765 Cowichan Bay Rd., Cowichan Bay, 250-748-2333, www.CowichanBayKayak. com.