There are at least 12 shark species that can be found in the Chesapeake Bay, but these species rarely pose a threat to human safety. Some—like the sandbar shark, sand tiger shark and smooth and spiny dogfish—are common, while others—like the bull shark, basking shark and bonnethead—are rare visitors.

People contribute pollution that can cloud the water and block sunlight from reaching bay grasses. This pollution comes from many sources, including farms, sewage, fertilizer and development.

A subwatershed is a small watershed contained within the larger Chesapeake Bay watershed. Each of the streams, creeks and rivers in the Bay watershed has its own watershed. For example, the Potomac River watershed is a subwatershed of the Chesapeake Bay watershed.

On average, the Chesapeake Bay is about 21 feet deep. However, most parts of the Bay are extremely shallow. A person who is 6 feet tall could wade through more than 700,000 acres of the Bay and barely get his or her hat wet. The Bay also has a few channels that are more than 100 feet deep, which provide important habitat for aquatic life and passageways for ships.

Some fish and crabs may be able to swim away from areas without enough oxygen. But other animals – such as oysters, clams and worms – are not able to swim away, and can die if there is not enough oxygen around them.

The Chesapeake Bay watershed stretches across more than 64,000 square miles.

Fish passage is the ability of fish to migrate up rivers, streams and other waterways, often to access spawning or rearing areas. Barriers to fish passage (which can include road culverts, dams, dikes and other obstructions) can reduce the distribution and habitat available to anadromous fish and, in some cases, eliminate fish populations altogether.

The Chesapeake Bay is the largest of more than 100 estuaries in the United States.

Epifauna and infauna are both types benthic, or bottom-dwelling, organisms. Epifauna live attached to a surface and infauna live within the Bay’s bottom sediments.

Just like any other plant, bay grasses go through photosynthesis, so they need sunlight to grow. This means that the water that bay grasses grow in must be clear enough for the sun’s rays to pass through.