FAQ
Explore our frequently asked questions to learn more about the Chesapeake Bay and its watershed, habitats and wildlife.
Bay Grasses
What are underwater grasses?
Underwater grasses, also known as submerged aquatic vegetation or SAV, are plants that grow in the shallows of the Chesapeake Bay.
How many types of grasses grow in the Chesapeake Bay?
About 20 species of underwater grasses grow in the Chesapeake Bay and in the lakes, streams, reservoirs and other bodies of water found throughout the watershed.
When do underwater grasses grow?
Underwater grasses have a growing season that typically runs from April through October.
Why are underwater grasses important?
Underwater grasses provide wildlife with food and habitat, add oxygen to the water, absorb nutrient pollution, trap sediment and reduce erosion.
How does temperature affect the growth of underwater grasses?
Extreme temperatures can have a negative effect on some underwater grasses. For example, eelgrass cannot grow in water that is too warm. In 2005, very high temperatures caused large areas of eelgrass in the lower Chesapeake Bay to die. Other species of grasses react positively to high temperatures and grow more quickly when the water is warmer.
Why do underwater grasses die?
Underwater grasses usually die because the water is too cloudy for sunlight to reach them. Cloudy water is most often caused by pollution from excess nutrients and sediment. Extreme temperatures and certain human activities can also cause underwater grasses to die.
How can people help underwater grasses thrive?
To support underwater grasses, boaters can follow posted speed limits and no-wake laws, and steer clear of any grasses growing in shallow waters.
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