What are excess nutrients?
Nutrients, such as nitrogen and organic carbon, are an important part of a healthy marine ecosystem, but too much nitrogen results in excessive algal growth and puts the health of the Puget Sound off balance. This algal growth occurs because nutrients act like fertilizer for algae and aquatic plants. When these algae and plants die, their decomposition uses up oxygen that marine animals needs to survive.
Why are they a problem?
Too much nitrogen and carbon in Puget Sound can lead to low dissolved oxygen, especially in shallower areas and bays. Low dissolved oxygen causes stress on aquatic species. In addition to low levels of oxygen, other effects of excess nutrients include:
- Acidification, which can prevent shellfish and other marine organisms from forming shells
- Shifts in the number and types or organisms that live on the seafloor, resulting in changes in the food chain
- Increases in nuisance macro-algae, which can impair the health of eelgrass and shellfish beds
- Increases in harmful algal blooms and other nuisance species, such as jellyfish
- Changes in food web dynamics
Where do they come from?
Natural processes and human sources contribute nutrients to Puget Sound. Nitrogen and other nutrients are also contributed to the Sound through ocean upwelling, which is when cold nutrient-rich water (which is also low in dissolved oxygen) moves from deep waters to surface waters. Nitrogen is also deposited by air into marine waters.
Human sources of nutrients can lead to the excess or imbalance of nutrients in Puget Sound. Sources of excess nutrients include:
- Wastewater, or "sewage", treatment plant discharges
- Using too much fertilize, which enters waterways when it rains
- Poor land management, especially with livestock
- On-site septic systems
What is Ecology doing about it?
We are working collaboratively with Puget Sound stakeholders through the Puget Sound Nutrient Source Reduction Project
and Puget Sound Nutrient Forum
to find solutions for reducing excess nutrients.