New tools for monitoring health of life at the bottom of Puget Sound

By Maggie Dutch, Senior Benthic Ecologist, Washington Department of Ecology


Up close and personal view of brittlestars taken by Maggie Dutch of Ecology's marine sediment monitoring program.

The sand and mud at the bottom of Puget Sound is home to a wide variety of microscopic invertebrates that scientists refer to as the “benthos.”


Microscopic creatures support the food chain

These organisms, living on or in the sediments, include worms, clams and snails, shrimp and crabs, sea cucumbers and brittle stars, and many other species. Near the bottom of the food chain, the benthos are an important source of nourishment for bottom feeding fish, larger bottom-dwelling invertebrates, sea birds, and even large species like bottom-feeding gray whales.

Ecology’s marine sediment monitoring scientists have been collecting benthos from sediment samples throughout Puget Sound since 1989. Our team of scientists sieves benthos from the sand and mud, and we count and identify each species. The number and types of species we find in each sample help to paint a picture of the overall condition and quality of the sediments and their ability to support this life.

For many years, our scientists have been using a Sediment Benthic Index to characterize the benthos collected from sediment samples as affected or unaffected by either natural or human-caused environmental stressors. We combine the results of this index with sediment chemistry and toxicity data to characterize sediment quality in eight regions and six bays, and to look for changes over time.

Recent sediment team reports have documented declines in condition of the benthos in the Strait of Georgia, Hood Canal, Central Puget Sound, Elliott Bay, Commencement Bay, and Bainbridge Basin.

Better tools = better information

Through grants from the Puget Soundkeeper Alliance and the U.S. EPA, Ecology staff collaborated with experts from the Southern California Coastal Water Research Project (SCCWRP) and EPA to develop new benthic indicators for Puget Sound. These indicators will characterize the benthos on a finer, more accurate 4-tiered assessment scale including undisturbed, low, moderate, and high disturbance categories. When applied to our Puget Sound benthos data, these new indicators will help us make a more refined assessment of the condition of the Puget Sound benthos.

To learn more about the new benthic indicators, read the 54-page report, Development of Puget Sound Benthic Indicators or go to the SCCWRP website

To learn more about Ecology’s Marine Sediment Monitoring Program, visit our website.

And the best is last. Check out some cool photos we've just taken of these amazing microscopic invertebrates.

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