Do you have a question about the Chesapeake Bay? Explore our list of frequently asked questions to learn more about the Bay and its watershed, habitats and wildlife. You can browse the FAQ by category, or explore the answers to some of our most common questions below.
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Underwater grasses, or submerged aquatic vegetation (SAV), have a growing season that typically runs from April through October.
Poor water clarity does not allow sunlight to reach bay grasses growing at the bottom of shallow waters. These underwater grasses provide food and habitat for many animals, including fish, crabs and birds. Without bay grasses, these animals may not have the food and habitat they need to survive.
Underwater grasses, also known as submerged aquatic vegetation or SAV, are plants that grow in the shallows of the Chesapeake Bay.
Underwater grasses are a critical part of the Chesapeake Bay ecosystem because they provide food and habitat for countless species. They also help keep the water clear and healthy by absorbing nutrients, trapping sediments, reducing erosion and adding oxygen.
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.
People contribute pollution that can cloud the water and block sunlight from reaching underwater grasses. This pollution comes from many sources, including farms, sewage, fertilizer and development.
Just like any other plant, underwater grasses go through photosynthesis, so they need sunlight to grow. This means that the water that these grasses grow in must be clear enough for the sun’s rays to pass through.
Underwater grass beds form communities that provide food and shelter for many species. Fish, crabs and other animals visit grass beds to seek out food and find shelter from larger predators. Underwater grasses are also an important source of food for waterfowl such as ducks and geese.
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.
About 20 species of underwater grasses grow in the Chesapeake Bay and in lakes, streams, reservoirs and other bodies of water throughout the Bay watershed.
Underwater grasses are a critical part of the Chesapeake Bay ecosystem. Without them, underwater creatures such as fish and blue crabs do not have the shelter they need to survive, and migratory waterfowl do not have enough food to eat.
Another important role of underwater grasses is to hold bottom sediments in place. If they are gone, waves can stir up bottom sediments and make the water cloudy. This can affect grass beds growing in other areas, because they need clear water to survive.
People can help save underwater grasses by reducing the amount of pollution they contribute to the Chesapeake Bay and its rivers. Three ways you can pollute less are: fertilize your lawn less, plant a buffer of trees and shrubs around your property, and maintain your septic system (if you have one). Also, when boating, make sure you don’t disturb grass beds in shallow areas.
SAV stands for submerged aquatic vegetation. SAV is more commonly known as bay grasses.
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