Subtidal (Offshore) Benthos

Benthic invertebrates, or benthos, are the worms, clams, snails, crabs, and more that live in the sediment at the bottom of Puget Sound. These animals are ecologically, economically, and culturally important. They play a vital role in the Puget Sound food web, being eaten by larger predatory animals in the sediment, by fish like salmon, and even people in the case of many mollusks, crabs, and urchins. 

Who lives where at the bottom of Puget Sound is influenced by what the bottom looks like (e.g., is it sandy or silty?), how deep it is, which chemicals are present, and who is eating whom. To better understand what is happening to this crucial part of the food web and what it can tell us about the health of that habitat, we collect benthos samples using a dual van Veen grab sampler. 

Samples tell us which and how many organisms are present. This information is collected with additional samples that are used to help us understand what the sediments are like physically and chemically and how they support different species. Benthos samples have been collected since 2015 from 14 sites. Every two years we sample eight sites in Elliott Bay and every five years we collect samples from three deep sites in the mainstem of the Central Basin and three smaller embayments.