Wetlands of Mayne Island

As the Biologist for the Mayne Island Conservancy, I get to visit some pretty cool places, and see some amazing things. Finding hidden patches of wildflowers in bloom, watching giant silk moths emerge from cocoons, and observing the graceful movement of kelp crabs balancing on the tips of an eelgrass meadow are just some that come to mind. In the past few years, I’ve had the pleasure of experiencing a new environment that is almost overwhelming in its natural beauty: wetlands.

Visiting a wetland in the spring or summer is like going to downtown Vancouver on a busy day, there is a LOT happening. Dozens of dragonflies and damselflies catch the eye with their flitting movement, violet-green and barn swallows pass overhead like silent fighter jets, red-winged blackbirds perch and dart about, dominating the soundscape with their iconic calls. In the background, the wind rustles sedges and rushes, whose brilliant green leaves emerge from the freshwater below.

Constant ripples across the surface of the water allude to the flurry of activity hidden beneath. Submerging a camera reveals the underwater world to be every bit as active as in the air above. Tadpoles nibble on algae with partially formed legs dangling behind them, aquatic beetles and backswimmers navigate the warm murky waters, seeking smaller prey for lunch. The cast of characters is too long to mention, and a lifetime could be spent studying the complex web of life found in these special places.

Energy Storage

There is a reason life is so abundant in a wetland. The perfect combination of sun and water make wetlands extremely effective growing places. The plants that grow there capture an enormous amount of energy from the sun, pulling carbon dioxide from the air during the process to help store the energy. Not only does that energy power a huge food web extending into the surrounding forest and beyond, but some of the carbon ends up buried in the mud, making wetlands an important part of our natural climate regulation. The lack of oxygen in the water-logged soils slows the decomposition process to a snail’s pace, trapping the carbon. When wetlands are drained, oxygen re-enters the soil, decomposition occurs, and the carbon is released into the atmosphere.

Water Filtration and Storage

Most wetlands on Mayne Island are very small, but they play an important role in freshwater management. As we observed in the Fall of 2021, heavy rainfall results in a lot of water moving across the surface of the land. The faster water moves, the more erosion it causes along the way, and the less trickles down to replenish our drinking water. Wetlands big and small act to slow and spread the flow of water, especially during heavy rainfall events. When water slows down, sediments suspended in the water have a chance to settle out.

In a past life, I was able to regularly observe differing levels of sediment suspension at the confluence of the Fraser and Thompson Rivers while working aboard the Rocky Mountaineer Train. The Fraser is a long muddy river that never gets a chance to settle down and drop its sediments. The Thompson, however, flows through Kamloops Lake, slowing down, dropping sediments, and coming out clear on the other side. When the two rivers meet at Lytton, they create a starkly contrasting, dual-coloured river for a time, until the larger flow of the Fraser absorbs the clear waters of the Thompson. On Mayne Island, wetlands perform this function in miniature. The amount of sediments flowing into our marine environment can have a significant impact on nearshore ecosystems such as eelgrass, which has declined by 26% around Mayne Island in the past ten years.

Once Abundant but Now Rare

Mayne Island’s wetlands and wettest forests are mostly gone, with 88% (as of 2005) having been drained and converted to agricultural (primarily hay and pasture) and residential land uses. We no longer benefit from the ecosystem services provided by those lost wetlands and wet forests. The loss of wetlands and wet forests continues on Mayne Island, motivated primarily by residential land development. By encouraging people to learn more about the essential services these ecosystems provide, we hope to encourage landholders on Mayne Island to conserve and restore the few remaining wetlands we have.

The Mayne Island Conservancy has begun restoration of two wetlands in recent years, one small wetland located at St. John Point below the parking lot, and a second much larger wetland at Hedgerow Farm in partnership with landholders Kristine Webber and Peter Robinson. We have provided advice to additional landholders through our free Landholder Consultation Program, many of whom are actively restoring and stewarding wetlands and wet forests on their lands. Caring for and restoring wetlands can be a rewarding experience. As mentioned, plants in these productive environments grow quite quickly, so changes happen more quickly than in drier ecosystems. Some benefits of functioning wetlands include mosquito control, erosion reduction, carbon storage, clean water, and wildlife viewing. If you have a wetland or wet forest you are interested in restoring or conserving, contact us for a free consultation. You can also check out this recording of an event about wetlands on Mayne Island, or read more about our local amphibians here.