Mayne Island Conservancy Society

Eelgrass Mapping Project

Eelgrass and Freedivers: Community-based Conservation and Restoration - Video produced by Leanna Boyer
Volunteer freedivers, kayakers and shore crew help the Seagrass Conservation Working Group conserve and restore eelgrass habitat

About Eelgrass

Native eelgrass (Zostera marina) grows throughout the B.C. coast, creating a nursery in intertidal and subtidal zones of estuaries and bays. Being one of the most diverse and productive (underwater) habitats in our coastal waters it provides critical habitat for many species of juvenile fish, migrating waterfowl, resident forage fish (Pacific sand lance), invertebrates and wading birds. It has been estimated that over 80% of commercially valuable fish and shellfish spend part of their life cycle in eelgrass beds.
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Volunteer Opportunities

For extensive volunteer opportunities in connection with the mapping and ongoing monitoring of subtidal vegetation of all kinds please go to the Shoreline Care page.

Eelgrass & Natural Capital

Sea grasses and underwater vegetation are under threat from ocean warming and human activity:

"Seagrass loss rates are comparable to those reported for mangroves, coral reefs and tropical rainforests, and place seagrass meadows among the most threatened ecosystems on earth," -- Proceedings of the National Academy of Sciences
"The ocean's vegetative habitats, in particular, mangroves, salt marshes and seagrasses cover less than 1% of the sea bed...and account for more than half of all carbon storage in ocean sediment and perhaps as much as over 70%...They comprise only 0.05% of the plant biomass on land, but store a comparable amount of carbon per year, and thus rank among the most intense carbon sinks on the planet" Oct 2009 report United Nations Environment Programme

"The services that nature provides for free are often not accounted for and, therefore, not properly valued by decision-makers. We evaluate the benefits that nature provides and calculate the economic cost of these services if we had to provide them ourselves" - What is Natural Capital? This resource material published by the David Suzuki Foundation provides the tools to evaluate the ecological services provided by the near-shore:

  • Carbon Sequestration: $25-$462/ha/yr
  • Carbon Storage:$32-$103/ha/yr
  • Nutrient Cycling: $16,989-$47,573/ha/yr
  • Habitat Refugium & Nursery: $4,744- $32,790/ha/yr
  • Mayne has roughly 35ha of eelgrass. For all of these services combined, our eelgrass earns us $762,650-$2,832,480 per year in ecosystem services
  • *note: eelgrass rated the highest for nutrient cycling and habitat & refugium - compare forest habitat & refugium at $5-$34/ha/yr.

Why Map & Monitor?

It is thought that in the last 100 years Puget Sound has lost more than 70% by area of its seagrass beds, while the U.N. estimates there has been a loss of 15% globally since 1999. The loss in B.C. waters is largely unknown and widespread efforts are underway to remedy this because:

·  Eelgrass provides valuable habitat·  Need to protect remaining populations
·  An indicator of nearshore health, keystone species ·  Early warning system for environmental problems
·  Identify locations for eelgrass restoration·  Highly significant carbon sink

Eelgrass Brochure Header

The impact of human activities are among the causes of seagrass decline; our Stewardship page lays out some of these activities and the way in which they might be countered or elminated altogether.

Biology: Eelgrass is a bright green ribbon-like grass that occurs in inter & sub tidal zones of sheltered muddy bays along 25-35% of the BC coast. As one of the planet’s most productive ecosystems eelgrass meadows are crucial in the carbon sequestration of greenhouse gases. In addition, these beds act as important spawning and nursery grounds for a variety of marine fish and invertebrates. Today, it is estimated that only 400 square kilometers of salt marsh and eelgrass meadows remain in the province which, combined draw down and store more atmospheric carbon than all of the province’s boreal forest, an equivalence of 200,000 cars/ year. Blue carbon as it’s known, has recently been discovered to be one of the major remaining planetary carbon sinks. "Blue carbon comprises half a per cent of the whole world's ocean surface and yet [it's] storing more than half of the carbon the ocean actually sequesters every year!” (Colin Campbell, BC Sierra Club Senior Scientist. 2012).

Threats: Worldwide eelgrass beds are among some of the most threatened coastal habitat as these fragile grasses are easily uprooted, shredded or trampled by human shoreline activities or industrial on land developments.

What you can do: Familiarize yourself with the location of eelgrass meadows in your area. Be aware Eelgrass is protected by law, under the Federal Fisheries Act, due to its high fisheries value (primary production, substrate for food organisms, spawning substrate and cover). As informed citizens you can choose to make a conscious decision to protect these ecologically sensitive marine ecosystems. If you find yourself in or around an eelgrass bed avoid dropping anchor, shredding plants with boat propellers or trampling as you move though during periods of low tide.

More information:
  • Seachange:
  • Seagrass Conservation Working Group's Facebook page
  • Britsh Columbia Chapter of the Canadian Parks & Wilderness Society:
    CPAWS in collaboration with the World Wildlife Federation recently released a report, “Climate Change Impacts and Vulnerabilities in Canada’s Pacific Marine Ecosystems.” The report is a broad review and synthesis of marine related climate changes that have been documented for our region with an added ecosystem vulnerability assessment component. An executive summary appears here. The report also highlights that many changes are already occurring and therefore will be useful to natural resource/marine managers and planners who are grappling with incorporating climate change considerations in their work, and reaffirm the need to do so.

Salish Sea Mapping Complete

Taken from a news release from the Islands Trust - Victoria, British Columbia, February 17, 2015: Maps of Eelgrass Beds in the Gulf and Howe Sound Islands Now Online.

Underwater camera survey results identify important marine habitat Complete mapping of eelgrass beds in the waters surrounding Canada’s islands in the Salish Sea is now available online. The Islands Trust Fund, SeaChange Marine Conservation Society and the Seagrass Conservation Working Group partnered on the three-year survey to increase local knowledge of the location and condition of the valuable eelgrass meadow ecosystem. The new maps are intended to support governments in preventing habitat loss as they make science-based decisions about land use and conservation in shoreline areas.

Eelgrass beds are a nursery habitat for fish, shellfish, birds and mammals. This important habitat provides food and protection for over 80% of the region's commercially important fish and shellfish species during some part of their life cycle. The marine plant is also an important carbon sink since it sequesters carbon at a much faster rate than the equivalent area of forest. Eelgrass is sensitive to docks, shading, mooring buoys and anchor chains, hardened shorelines and contaminated or silt-laden runoff from land.

A boat towing an underwater camera surveyed the marine environment to locate eelgrass beds. This technique results in a high level of mapping accuracy, greatly improving upon existing data and filling in gaps where inventories didn’t exist. The Mayne Island Conservancy Society provided existing data for Mayne Island while Parks Canada provided data for shorelines surrounding Gulf Islands National Park, resulting in a complete data set for all of Canada’s islands in the Salish Sea.

Local governments and island communities can use the new maps when considering community education programs, land use bylaws and development applications along the shoreline. Conservation groups can also use this knowledge to focus their efforts where most needed.

“The eelgrass mapping project has been a great example of how a local government can work with a non-profit agency to compile and share information,” said Jennifer Eliason, Manager of the Islands Trust Fund. “We have had many requests for information about eelgrass beds and we are pleased that results of this survey are being used by our organization and others.”

The text of the full report (.pdf) is here and the referenced maps are at ecosystem-maps-%28pdfs%29.aspx

Remote Sensing Lab Studies

Eelgrass tudies undertaken by the Spectral Remote Sensing Lab at UVic are ongoing using High Angle UAV's. Surveys took place on Mayne Island at the end of June 2016. Our Facebook page has the story and results can be found on the UVic project page.

Eelgrass Video 2016

The Divers' 2014 Visit

Right at the beginning of the Shoreline Care Project in 2007 we had the underwater assistance of members of the Vancouver Apneist Free Divers Club in defining the edges of the eelgrass beds in various bays and coves of Mayne Island. After establishing a baseline the Apneists and Conservancy volunteers continue to monitor year on year changes in the extent, and health of our eelgrass beds and kelp meadows

This year the Free Diver group helped us monitor the changes in Miners Bay and after the weekend, writing to Leanna Boyer, Project Lead for Shoreline Care, Tom Lightfoot of the Vancouver Apneist Club commented, in part:

We really did have good conditions this year and it does remind me that it feels that there have been more good visibility days in recent years and that the surface temperature has been warmer as well. I think it would be a good idea to continue with those light/temperature monitors and to ensure that there are enough of them so that you can get a good multi-year data set that you can correlate with your eelgrass data. If I'm right about the visibility trend then it might be good for eelgrass but bad for filter feeders.....(We) always look forward to these eelgrass weekends on Mayne (and) it's .. great to see you and to work with (the Conservancy).
Naturally we are grateful for the volunteer work the divers do for us and we hope to welcome them back again for their 8th visit in 2015.

Facts & Stats

Mapping the Eelgrass beds in the intertidal and subtidal areas of Mayne Island's bays and beaches involved:

  • 280,000 square metres delineated, surveyed & mapped
  • 30 volunteers
  • 224 volunteer hours over 28 days
  • We did not record the number of minutes during which the apneists didn't breathe
  • No kayaks holed, and no GPS devices drowned!

More Pictures

2010 - July 17th & 18th with the Apneists

Kayaks at the Ready
Kayaks ready on Gallagher Bay
This way to help with the project
How Volunteers Found Us
Kayaker & Diver On The Job
Apneist Marks for Kayaker's GPS
Two Divers Work with a Kayaker
Discussion about the Next Dive
Divers relax before Saturday Supper
Saturday Supper Next Up!

2009 - First Project Results

Eelgrass & Sand Lance Map
Eelgrass & Sand Lance beaches
Eelgrass Display at the 2010 MICS Open House - Map of Miners Bay
Eelgrass Beds in Miners Bay
EG & SL Display at a 2009 Farmers Market
The Project Presence at a Farmers' Market
Taking Inventory along an Intertidal Transect
Taking Inventory along a Transect
Eelgrass display: map of Gallagher Bay
Eelgrass Beds in Gallagher Bay

You can find many more photographs and illustrations of the Shoreline Care Project in action by visiting our Gallery pages

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