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.

Bay 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.

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.

An oyster reef is an example of a benthic community.

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.

The Chesapeake Bay is about 200 miles long, stretching from Havre de Grace, Maryland, to Norfolk, Virginia. The Bay’s width varies from its narrowest point (3.4 miles across near Aberdeen, Maryland) to its widest point (35 miles across near the mouth of the Potomac River).

There are many low-impact development techniques that can be installed around homes and buildings. Rain gardens, porous pavement and green roofs are a few techniques that will help reduce pollution from developed areas.

The Chesapeake Bay is saltiest at its mouth, near Hampton Roads, Virginia. This is where salty ocean water comes into the Bay. The Bay’s salinity decreases as you move north.

Poor water clarity is usually caused by a combination of suspended sediments, organic matter and excess nutrients that fuel the growth of water-clouding algae. Weather also plays a large role in water clarity. Rain storms can wash dirt and pollutants into the Bay and cause the water to look muddy. During drier conditions, the water is usually clearer.

Scientists generally agree that the Bay’s creatures need dissolved oxygen concentrations of 5.0 mg/L or more to live and thrive. However, the amount of oxygen an animal needs varies depending on how large or complex the animal is and where it lives.