Higher trophic-level function of seagrass-vegetated and unvegetated tideflats in Washington

Principal Investigator

Jennifer Ruesink, University of Washington, Department of Biology

Co-Principal Investigators

Tom Good, NOAA Fisheries

Cinde Donoghue, Washington Department of Natural Resources

Project

To better understand the benefits of eelgrass, Washington Sea Grant researchers worked in collaboration with the Washington State Department of Natural Resources to determine the distribution of higher trophic-level species at low intertidal elevations where eelgrass are interspersed. Fish, shrimp and crabs were sampled by seine at five sites around the state. Successful field sampling allowed the team to include effects of patchy areas of eelgrass versus eelgrass meadows.

Research Updates

Background

Many resource managers assume that Washington’s native eelgrass provides essential habitat for fish and birds. However, only a few studies have compared these species around eelgrass in Washington State, so uncertainty exists about the use of eelgrass seasonally and by different species. Filling these knowledge gaps would be useful for valuating eelgrass as an ecosystem benefit.

Results 

The study resulted in a rich dataset on eelgrass and creatures that live amongst eelgrass. They found that 21 coastal nekton species span a continuum of association with eelgrass, although juvenile salmonids were not strongly associated with eelgrass. Species using eelgrass as habitat varied seasonally, peaking in summer. In Washington, eelgrass can occur in a wide range of configurations, from small patches of fringe eelgrass to extensive meadows. Surprisingly, fringe patches harbored more species than meadows. The team developed an effective, low-cost seine for sampling eelgrass, which is now being used by other researchers.