Marine water quality refers to aspects of water such as temperature, salinity, oxygen, nutrient levels, algae biomass, and pH. In much of Puget Sound, marine water quality is affected by many different factors including weather, climate and circulation patterns, offshore ocean conditions, inflow from rivers and streams, discharges from wastewater treatment plants and industries, erosion and stormwater runoff, ground water, and pollution.
A functioning, resilient Puget Sound ecosystem also includes marine sediment quality that supports healthy communities of sediment-dwelling invertebrates. The sediment (gravel, sand, silt, and clay) on the floor of Puget Sound forms a unique habitat that is home to clams, marine worms, burrowing shrimp, bottom-dwelling fish, and thousands of other unique species. In turn, these animals form a critical part of the marine food web, are instrumental in mixing and oxygenating the sediments, and they process the sediments allowing nutrients to cycle between the sediments and the overlying waters.
This Vital Sign tells us about the condition of marine waters and associated sediment and the combined impacts of global change and local human-caused stresses. The Marine Water Vital Sign also helps us understand whether efforts to reduce pollutants to marine waters are effective.
VITAL SIGN INDICATOR | INDICATOR PROGRESS | TARGET STATUS |
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VITAL SIGN INDICATOR | INDICATOR PROGRESS | TARGET STATUS |
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Although Puget Sound may look beautiful from the surface, marine water quality has changed in many ways. Monitoring programs document marine water quality and how Puget Sound changes over time. One challenge is gathering enough data – especially historical data – to truly understand what the ecosystem used to be like compared to now. Shifts over time in the expectations for a healthy ecosystem is referred to as “shifting baselines”. By establishing scientifically sound baselines for water quality parameters, researchers can detect changes and predict what Puget Sound will be like for future generations.
Many unknowns exist regarding Puget Sound’s future. Climate change is impacting the water cycle throughout Puget Sound, altering the seasonality and timing of key chemical, physical, and biological processes. Climate is a huge driver of marine water quality and the marine food web. As climate changes, so does the way plants and animals live in Puget Sound and how humans use Puget Sound’s resources.
Three decades of monitoring sediment chemistry, toxicity, and benthic invertebrates indicate: