Changes to long-term status and trends sediment monitoring to assess nutrient enrichment and climate change pressures in Puget Sound

Long-term monitoring of Puget Sound sediments and sediment-dwelling invertebrates (benthos) has been conducted by the Washington State Department of Ecology since 1989 as part of the Puget Sound Ecosystem Monitoring Program. Like sediment programs developed for estuaries nationwide, this Puget Sound program was designed to characterize the impact of toxic contaminants from point-source discharges on the receiving environment. Thirty years of monitoring results indicate that: 1) chemical contaminants are low and below critical thresholds in most non-urban Puget Sound sediments; 2) sediments are non-toxic in 88% of the Puget Sound study area, with low-level toxicity increasing in both urban and non-urban terminal inlets; and 3) benthos abundance and taxa richness have declined in terminal inlets and other locations. Little correspondence was seen between chemistry, toxicity, and benthos measures, and findings suggest that benthos changes may be in response to nutrient loading and climate change, rather than chemical contamination. The sediment program had been redesigned to better assess these pressures. The sampling frame and periodicity have been revised, and sampling locations are aligned with those of other monitoring programs for better comparison of data. Also, while contaminant monitoring will continue, the parameter list has been expanded to include benthos biomass and ecological function, and a new suite of biogeochemical parameters which may be better indicators of Puget Sound nutrient and climate change. The new Puget Sound sediment monitoring design will be presented. Additionally, a brief session summary will highlight links between Puget Sound monitoring programs which have led to new questions, hypotheses, and indicators which can help us better asses the effects of nutrient loading and climate change on fragile Puget Sound habitats and biota