Seagrass Monitoring in Puget Sound (2000-2020)

What we have learned

Map of Salish Sea

Greater Puget Sound (darker blue) as delineated by the Washington State boundary out to Cape Flattery.

Welcome

The  Nearshore Habitat Program  monitors seagrass meadows in greater Puget Sound - an area that encompasses over 3000 km of shoreline and includes Puget Sound proper, the San Juan Islands, the Strait of Juan de Fuca, Hood Canal and Saratoga Passage. It is part of the Salish Sea which is shared by Washington State (US) and British Columbia (Canada).

This storymap gives an overview of spatial data describing where seagrasses are found and where we have observed changes over the 2000-2020 period. We also describe the methods we use and why we are conducting this work.

We welcome comments and questions.

Logo of the Washington Department of Natural Resources

Where seagrass is found

How Seagrass is Changing

Overall, our results show that the seagrass population displays a strong degree of stability, but a sizable proportion of sites display evidence of change - both increasing and declining trends in native seagrass. Most concerning are aggregations of declining sites, particularly in the San Juan Islands, that suggest the possibility of a regional scale stressors that are not well understood with unknown future trajectory.

First we present results from evaluation of sites for changes in the area of native seagrass. This analysis is only possible at sites that have been surveyed repeatedly over time. If a site has sufficient data over a period of greater than 5 years, then we will evaluate the site for long-term trend in native seagrass area.

How Seagrass Data is Collected

Studies

Our monitoring work involves many different studies.  Each study has its own area of interest, objectives and timeframe.

Most of our work is part of the ‘soundwide’ study. In this case, sites are selected randomly from over the entire study area. This allows us to make unbiased estimates of the total seagrass area and the associated confidence interval.

In the 2000-2020 period, the soundwide study was responsible for 61% of our site samples. The remaining monitoring work has been divided among many studies that are frequently conducted with a partner organization. The spatial scope and design of the study reflect the interests of the partner organization. Combined, these studies expand the seagrass database and our understanding of seagrass distribution and status considerably.

In addition, three organizations have shared seagrass survey data they collected.  We have included their data as three additional studies in our monitoring database. These data are included courtesy Friends of the San Juans, Clallam County and the Island County Marine Resources Committee (MRC). 

Scroll down to see a dashboard that lets you explore the studies.

ArcGIS Dashboards

Why monitor seagrass?

"If you care about salmon, if you care about orca, if you care about birds, if you care about forage fish, then you don't know it, but you care about seagrass" Helen Berry WA DNR 2021

Helen made a similar quote in a King 5 interview with Michael Crowe. You can see the interview that focuses on kelp   here  .

Nearshore vegetation plays an important ecological role for species that might be more recognized and valued by the public.

The ecological role of seagrass includes sustaining food webs that include many species. They are ranked among the most productive and valuable habitats in the biosphere and provide food and shelter for a wide variety of animal species, including benthic invertebrates, commercially important fish species, wading birds, turtles, dugongs and manatees. Seagrasses are also able to reduce erosion and improve water quality by stabilizing sediments with their roots and rhizomes.

Monitoring provides the basic information needed for informed natural resource management that encompasses seagrass itself but also other valued species that rely on seagrass.

Also, seagrass is sensitive to environmental degradation including declining water quality. This makes seagrass valuable as an ecosystem indicator. Our monitoring currently is used as a Vital Sign indicator by the Puget Sound Partnership.

Washington governmental agencies recognize the value of seagrass as an aquatic resource and provide it special protections. The Washington State Department of Fish and Wildlife (WDFW) has designated seagrass areas as habitats of special concern (WAC 220-660-320) under its authority to regulate construction projects in state waters (RCW 77.55.021). The Washington State Department of Ecology has designated eelgrass as critical habitat (WAC 173-26-221) under its statutory authority in implementing the state Shoreline Management Act (RCW 90.58). In 2011, the Puget Sound Partnership adopted a restoration target for native seagrass that reflects a 20% gain in area by 2020 relative to a 2000-2008 baseline (Puget Sound Partnership 2011). 

WA DNR led an effort to develop a seagrass recovery strategy for our study area. This document can be viewed  here .

Explore the Dataset

Scroll down to interact with the 2000-2020 seagrass monitoring dataset in a web application. Alternatively you can view the web application in a new window by clicking the button below.

The entire monitoring dataset is also available as two Zip archive downloads. The button below will initiate a download of the main monitoring dataset.

The detailed transect data based on the underwater video is a large download (267 MB). The button below will initiate a download of the transect data.

Puget Sound Seagrass Monitoring - Web Application

Credits

The organizations below have generously contributed data to the Puget Sound Seagrass Monitoring Dataset. You can see details on the data from these organizations at the dashboard in the 'How Seagrass Data is Collected' section of this storymap, or at this direct  link .

Contributed data in the San Juan Islands

Friends of the San Juans

Contributed data within Island County

Island County Marine Resources Committee

Contributed data near the Elwha River

Clallam County

Greater Puget Sound (darker blue) as delineated by the Washington State boundary out to Cape Flattery.