How Nutrients Harm the Bay
- Excessive nutrients cause algae to grow rapidly. When the algae decompose, they use up a lot of oxygen in the water, depriving fish and shellfish of the oxygen they need to live. Fish kills occur during these “low oxygen” or “hypoxic” events.
- Nutrient pollution clouds the water, robbing eelgrass of the sunlight it needs to grow. Eelgrass is a primary source of food and shelter for many marine species, including economically important finfish and shellfish. It also protects the shoreline by dampening wave energy and reducing erosion. Eelgrass is widely recognized as a key indicator of estuary health. Unfortunately, Narragansett Bay, once teeming with eelgrass, has lost 90 percent of its eelgrass beds.
- Excess nutrients can create large, deep mats of sea lettuce—a type of seaweed—depriving bottom-dwelling marine plants and animals of sunlight and oxygen. When these mats of algae wash up on shore, the stench of the decaying seaweed makes for unpleasant beaches.
- Excess nutrients can lead to overproduction of certain kinds of phytoplankton, which can cause diseases in fish, shellfish and people.