Eelgrass Monitoring on SḴŦAḴ | Mayne Island- a Deep Dive with Eden

Published by Eden Perry on 07/02/2025 07/07/2025

The Mayne Island Conservancy’s 2025 eelgrass monitoring season is officially underway! My name is Eden, and I am one of the Ecosystem Technicians this field season. One of the exciting projects I am a part of is mapping eelgrass beds around the shores of SḴŦAḴ | Mayne Island. I never imagined I would get to freedive and kayak for work, and I want to share my experience gaining confidence while conducting research in the water alongside all the incredible marine life we are fortunate to have here in coastal British Columbia.

The Conservancy began conducting eelgrass mapping surveys in 2009, and the number and locations of sites mapped has varied throughout the years. At sites that have been surveyed multiple times, we are able to detect and visualize changes in the presence of eelgrass throughout the bed. This year seven locations were selected: Miner’s Bay, Naylor Bay, Campbell Bay, Bennett Bay, Horton Bay, Dinner Bay, and Village Bay.

This year’s eelgrass team is comprised of me, our Stewardship Coordinator Justine Apostolopoulos, and our Biologist Rob Underhill. During the survey, two of us are in the water visually identifying the edge of the eelgrass bed by taking turns with the exhilarating role of diving down to survey underwater when the grass-like shoots are too deep to see from the surface. While this is occurring, the third team member is following us closely in a kayak to record the bed edge with a GPS unit and take depth measurements. Five sites in, we have gotten our routine down and it has become like a synchronized dance in the water when we have suitable tidal and visibility conditions.

The importance of eelgrass ecosystems cannot be overstated. As one of the most productive habitats in the ocean, eelgrass beds provide spawning surfaces for Pacific herring, shelter for young fish, and foraging habitat for migratory waterfowl such as mallard ducks. This remarkable seagrass reduces coastal erosion by stabilizing sediments and reducing the force of waves on the shoreline. They also act as important carbon sinks by trapping carbon in marine sediments and produce abundant oxygen – some even call them the “lungs of the sea”.

While I’ve had a long-held fascination with kelp and other types of seaweeds, eelgrass (which is actually a flowering plant) has joined the species I look for during a low tide. In our most recent survey in Campbell Bay we saw thousands of shiner perch scurrying throughout the bed, as well as juvenile salmon and charismatic pipe fish. Before the survey began, I was able to take a couple minutes simply floating in the water and watching the bustling marine life we don’t often witness day-to-day. I’ve included a slideshow below of some of my favorite creatures we have witnessed lurking in the intertidal zone in recent years.

While the experience of the eelgrass survey is one the highlights of my career so far, it occurs in the context of stark declines in eelgrass bed size locally, and around the world. In the sites that we monitor at the Conservancy, we’ve observed a decline of 32.5% in the area covered by eelgrass between 2009 and 2024. The reasons for this loss are diverse and vary between locations. Some of the leading contributors to declines are competition with sea lettuce for light, erosion from shoreline development, sediment disturbance from boats in high traffic areas, physical damage from the anchors of moored boats, and biological factors such as the grazing pressure of non-migratory Canada geese.

Calls to Action

Organizations like the Mayne Island Conservancy and land stewards around the world are working hard to protect eelgrass for future generations and the health of our ocean. There are also things you can do, such as:

• Avoid anchoring boats in eelgrass beds, which can damage or uproot the plants.
• Maintaining vegetation and forests alongside aquatic ecosystems such as streams, creeks, and shorelines to prevent erosion, and sediment entering the water.
• Maintaining or adding water permeable surface and/or wetlands on your property to slow the flow of surface water into the ocean.
• Donating to the Conservancy to support our work of monitoring, reporting, and advocating for marine ecosystems.
• Volunteering with us as a Marine Citizen Scientist– our 2025 bull kelp monitoring season is coming up and we are looking for volunteers! See this post for more information and contact us at biologist@mayneconservancy.ca.