Puget Sound sediments

Puget Sound sediments and the invertebrates, known as benthos, that live within them are a vital component of the Puget Sound ecosystem. Our team of scientists collect data about the sediments and benthos. These data are used to evaluate environmental threats and to guide the state’s environmental policy decisions.

Monitoring the bottom of Puget Sound

Puget Sound sediments provide critical habitat for bottom-dwelling invertebrates and fish. They can trap and release harmful chemicals, and key nutrient-cycling processes occur within sediments. Benthos play a key role in sediment processes and are a vital link in both the benthic and pelagic food webs. In addition, many Puget Sound benthic invertebrates are harvested commercially and are important to the local economy.
Sediment monitoring stations and sampling frames.

Addressing key questions

Our Marine Sediment Monitoring Team has studied Puget Sound sediments and benthos since 1989. To assess conditions in response to climate change, nutrient loading, and toxics-related pressures, the following questions are addressed:

  • What is the condition of the benthic habitat, including sediments, porewater, and their associated invertebrate assemblages?
  • How does benthic condition change over time in response to inputs of carbon, nutrients, and chemical pollutants to the system, and in response to climate-related pressures?

Monitoring stations

To assess sediment and benthos quality, we sample 50 long-term stations throughout Puget Sound every April. Station locations are indicated by dots on the map to the right. Our Puget Sound sampling frame is highlighted in yellow and red.

We also sample 30 to 36 stations every June from one of six urban bays nested within the Puget Sound sampling frame. These bays are shown in red on the map. Each is sampled on a six-year rotation.

What we measure

We measure several types of parameters at each sediment-sampling station, including:
Data are collected on: enumeration, lowest taxonomic level identification, size class, biomass estimates, and ecological function. To learn more you can visit our web page on scientific descriptions of species: benthic invertebrates in Puget Sound
Data are collected on: total carbon, total organic carbon, total inorganic carbon, total nitrogen, C:N ratio,  total sulfides, biogenic silica, δ13and δ15N stable isotopes.
Data are collected on: metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and phthalates.
Data are collected on: temperature, salinity, station depth, and grain size.
We partner with other regional scientists, providing sediments for studies that assess microplastics, foraminifera communities, harmful algal blooms, and environmental DNA (or eDNA).

Other parameters being examined in pilot studies include nutrients in water-column particulates, and nutrient- and dissolved oxygen-flux rates as measures of sediment diagenesis.

Our monitoring products