· Rich Estuary
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· Looking Ahead

Global 200 Snapshot

The Chesapeake Bay is one of the world's largest and most productive temperate estuaries.  

Rich Estuary

Whether it floats, swims, digs, dives, flies, creeps, stays put or just plain tastes good, you can’t move an inch in the Chesapeake Bay without running into an animal. Jellyfish, sea turtles, fish, worms, birds, snails and oysters are only a few of the kinds of animals found in this ecoregion, along with plants like microscopic diatoms, large tufts of sea lettuce, marsh cordgrass, and underwater eelgrass. An example of an estuary, or area where salt water from the ocean mixes with freshwater from rivers and streams, the Chesapeake Bay has a mixture of freshwater and marine organisms and is teeming with life.

Special Features

From beaches to muddy flats to marshes, seagrass meadows and oyster reefs -- the Chesapeake Bay contains diverse habitats, each perfectly suited to different plants and animals. Large rivers feed the ecoregion, including the Susquehanna, James, Potomac, Patuxent, and Chester, each bringing nutrients that help make this bay one of the most productive areas on earth.

When Europeans first arrived in the Chesapeake Bay nearly 400 years ago, oysters were so plentiful that oyster reefs posed navigation problems for Captain John Smith’s boats. Oysters filter small microscopic organisms from the water, helping the water stay clean. In John Smith's day, the oysters could have filtered all the water in the Chesapeake Bay in just a few days, but today so few oysters remain that it takes months for today’s populations to filter that much water.

Wild Side

Blue crabs dig through the mud for clams and worms. Striped bass, American shad, and alewife migrate through salty water to reach freshwater regions where they lay their eggs. Sea horses and pipefish wrap their tails around seagrass blades and use their snouts to suck in small crustaceans that blunder too close. Brown pelicans fly high and then suddenly plunge into the rivers, catching unlucky menhaden and other plentiful fish. Sea slugs and flatworms crawl between fan worms, barnacles and sea squirts, all of which live on top of oyster shells. Northern diamondback terrapins, a kind of turtle, stretch out in the sun, while between the cordgrass stalks in salt marshes, male fiddler crabs wave one large claw to impress the females. And countless other birds, fish, dolphins and invertebrates eat, sleep, and grow in the Chesapeake Bay.

Cause for Concern

Runoff from urban, suburban, and agricultural areas carries fertilizing nutrients into the water, stimulating the growth of algae, an aquatic plant. When the algae eventually die and decay, oxygen needed by marine animals is used up, creating "dead zones" where many animals can’t live. Algae also prevent sunlight from reaching seagrasses, killing these critical plants that provide habitat for juvenile fish and blue crabs. Introduced species like the Rapa whelk, a large snail originally from Asia, threaten native species, and toxic algal blooms can harm fish and people. Overfishing and habitat destruction have also caused declines of important populations like oysters.

Looking Ahead

The Chesapeake Bay Program, a group of government agencies and representatives from states in the Chesapeake Bay area, is working to reduce nutrient inputs into the Chesapeake Bay and restore seagrasses, oysters and other important living resources.