Thursday, January 05, 2006

Eelgrass mapping in Possession Sound and Port Susan

The Snohomish County, in partnership with the Tulalip Tribes and the Northwest Straits Initiative, is running aerial surveys of the shoreline that show shallow eelgrass plant locations. But because eelgrass can live 20 feet below sea level, more mapping is needed, so the county plans to do underwater eelgrass mapping in the spring or summer, Frenzl said.

The county has a $14,000 grant from the Northwest Straits Initiative and hopes to get more grant money before the mapping starts. The Initiative is set up to help counties in the north Puget Sound area work to protect the water body that links them together.

Eelgrass, which washes back and forth with the tide, provides habitat for tiny fish that salmon eat. Eelgrass also provides cover for young, dime-size Dungeness crab.
The eventual goal is to determine whether eelgrass is in decline, stable or growing.
Perhaps the biggest threat eelgrass faces is too much sediment in the water, something that also threatens salmon and other marine life, Frenzl said.

Erosion brought on by farming or development near streams and rivers puts extra sediment into river systems - sediment that flows into Possession Sound and Port Susan when rivers run high. The sediment blocks sunlight, which causes eelgrass to die. The mapping will help gauge whether the sediment is causing eelgrass patches to shrink.