Eelgrass Mapping

Kelp & Eelgrass Mapping Project

A Copper Rockfish in the Seagrass
Photo credit: Sharon Jeffery

Bull Kelp & 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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"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

Bull Kelp (Nereocystis luetkeana) is an annual marine seaweed that is common throughout the Gulf Islands. Its range extends from Alaska to California, and it provides important habitat for many kinds of marine life. The plant consists of a long stipe (up to 36 m long), attached to the ocean floor by a holdfast and buoyed at the ocean's surface by a float, which allows the cluster of smooth blades to obtain light. Kelp beds look like forests underwater, and create habitat for crustaceans, plankton, snails, juvenile salmon, rockfish, surf smelt, and other marine life. Predators such as harbour seals, sea lions, sea birds, and even orcas hunt around these kelp forests. Kelp swept away by storms can wash up on shore where it is then eaten by decomposers or may sink into deeper water and feed other food webs.

Kelp beds may be negatively impacted by changes in the ocean floor composition or by changes in salinity and temperature of the water. A loss of animals that feed on dead material and remove silt and debris, such as sea cucumbers, and an increase in herbivores such as sea urchins, can also have a negative effect.

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

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.

Latest News

2009: Eelgrass and other seagrass species have been identified as indicators of nearshore health around the world. Up until the beginning of this project there has been only coarse scale mapping (1:20,000) of eelgrass on Mayne Island. Between May and September of this year all known eelgrass beds were mapped (delineated) at a fine scale with the help of volunteers. The summer weather was good to us resulting in the participation of 30 volunteers over 30 mapping days, totalling 230 volunteer hours. The goal of mapping the entire island using GPS could not have happened without volunteers.

May 2010: The grade 4-8 class, along with volunteers, counted the intertidal eelgrass in Gallagher Bay. The afternoon's work involved counting the number of stems in plots (which were randomly located along a 60 m transect) and measuring and calculating the "Leaf Area Index." The purpose was to expose kids to the methodology of a real scientific project in marine ecology/biology. More pictures on the Education page.

July 2010: Thanks to all the volunteers that helped monitor Gallagher Bay for a second year in a row! In May the grade 4-8 class counted eelgrass shoots in the intertidal zone and we found a significant increase in density, likely due to our warm winter. On July 17-18, 5 volunteers from the Vancouver Apneist Freediving Club delineated the bed by deploying floats. Kayakers then came along and recorded GPS points. Tom Lightfoot, Club president, organized the volunteers on the Vancouver side but was unable to make it due to illness, thanks Tom! Cynthia Durance, our scientific advisor for eelgrass, joined us this year and helped to refine the methodology.

August 2010: Conservancy kayakers with GPS in hand mapped the bull kelp beds along the shores of Mayne Island. The island's entire 45,000m shoreline was circumnavigated in order to collect the data for this project, which provides an initial map of the state of this important (see news item from the Sierra Club here) marine habitat as a baseline for future monitoring. MICS received a very high level of community participation and enthusiasm for this project, and without the many volunteer hours that were dedicated by community members it could not have taken place on such a large scale. The schedule is dictated by the tides, which means that on certain days mappers had to be up before the sun in order to be on the water as early as 5:00am. Many thanks to everyone that helped out this summer!

October 2010: The summer's mapping activities have now beem compiled and plotted on an updated Eelgrass and Kelp bed map of Mayne Island - click on the thumbnail to the left to see a readable version

Meanwhile our Executive Directorr assisted the Sierra Club of B.C. in their 10-10-10 observancies:

"...thanks to our amazing team of volunteers who carpooled and rode their bikes to the work party. Sierra Club BC marine campaigner Colin Campbell told the fascinating story of eelgrass and climate change, and Nikki Wright explained why eelgrass is worth conserving. Leanna Boyer of Mayne Island Conservancy demonstrated how to carefully separate strands of eelgrass collected from abundant beds and weight them for planting. A diving boat, courtesy of Rockfish Divers, and two divers were on hand for the seabed part of the work."

Follow the link to see a video of the "Mudboots Party: Restoring Eelgrass Meadows" on Oct 6th. We understand that Stella helped Leanna tie eelgrass to washers: http://www.youtube.com/watch?v=9MRB2v3YAIY

January 2011: We are working on a kelp mapping and monitoring methodology, based on the mapping that MICS completed in the summer of 2010.This document is being prepared in collaboration with the Seagrass Conservation Working Group, and will be contributed to by other groups and experts working in the region. Once completed it will serve as a guide for other community groups on BC’s coast who wish to map and monitor canopy-forming kelps (Bull Kelp and Giant Kelp).

What's Next?

For 2010-11 the Eelgrass Project has become part of the "Shoreline Care" programme of the Mayne Island Conservancy as mapping efforts expand to incorporate kelp forests and other subtidal plant growth.

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!

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.