Eelgrass (Zostera marina) is important to the Salish Sea as habitat and food for many animal species, as a source of carbon sequestration and nutrient cycling, and as a sediment filtration system. It is an indicator species for ecosystem stress, pollution and environmental health of the Sound.
Over the last eight years our team and volunteers have measured the eelgrass bed areas for over 37 different sites (1000 meters of shoreline) in Island County to determine the status of this important resource. We have used a combination of underwater video and aerial photography to characterize the eelgrass beds in the near-shore.
Some of the sites were re-measured every year (Cornet Bay, Monroe Landing in Penn Cove and Freeland Park in Holmes Harbor), some have been re-measured every three years (other Penn Cove, Holmes Harbor, South Whidbey and Camano sites) and still others were measured for specific events (construction or extreme weather events). In all we have measured the bed areas nearly 80 times and have an aerial photographic record of the entire shoreline in Island County. To date almost all of the sites have been shown to be stable within our limits of detection, a few have shown changes of bed patterns within the site and two have significantly increased bed areas (good news!).
This year Albert Foster single-handedly explored the use of multi-beam sonar as a new tool to measure underwater vegetation. We will be comparing his results to our more conventional underwater video and aerial assessment to determine how this technique may be used in the future.
Our work is supported by the Northwest Straits Commission, managed by the Island County Marine Resource Committee and collaborates with WA DNR. For a more complete description of the project and results please contact Gregg Ridder.
The Eelgrass team includes Tom Vos, Ken Urstad, Kes Tautvydas, Gregg Ridder, Mark Kennedy, Bob Gentz, Albert Foster and Neal Clark