Graphic showing an interaction of various ecosystems

The mixing of freshwater with saltwater from the Atlantic Ocean in the Chesapeake Bay creates the nation's largest estuary, home to more than 3,700 species of plants and animals. Estuaries are highly productive environments because they provide a variety of habitats, which in turn support a great diversity of life.

About half of the Chesapeake's water volume comes from the saltwater of the Atlantic Ocean. The other half comes from freshwater rivers and streams that drain into the Bay from its 64,000-square-mile watershed. The Chesapeake estuary, the surrounding watershed, and the variety of organisms that live in this environment make up the Chesapeake ecosystem. All elements of this ecosystem interact with each other in some way, depending directly or indirectly on each other for survival.

We can see this interconnectedness in the decline of some of the important species that live in the Chesapeake ecosystem. Although a combination of natural and human factors may be responsible for the decline, the most common cause is the loss of habitat.

In the following sections, explore the key habitats of the Chesapeake Bay ecosystem and some of the challenges they face.

Healthy habitats are the key to healthy plants and animals. Each species has particular habitat needs that must be met for survival. There are six types of habitats in the Chesapeake Bay watershed. Explore them below.


The Chesapeake Bay watershed has a wide variety of complex ecosystems including: Navigation



A forest is an area that is mainly covered by woody plants and trees.

Forests are critical to the health of the Chesapeake Bay. Large areas of trees perform important ecological functions such as cleaning our water and air.

Forests provide clean water:

  • Forests are like giant sponges, trapping pollutants and nutrients from flowing into our rivers and streams
  • Streamside forests, also known as riparian buffers, can reduce the amount of nutrients running into waterways by as much as 30% to 90%
    • Forests currently buffer about 60% of the streams and rivers that flow into the Bay
  • Mature trees have deep root systems that hold soil in place, helping to stabilize streambanks and reduce erosion

Forests protect clean air:

  • Through a process known as attenuation, tree roots, leaves, and forest soils can absorb and trap pollutants in the air
  • Forests can capture more than 85% of the nitrogen that falls on them from the air, keeping it from running into our waterways
    • Excess nitrogen in our water can fuel the growth of algae blooms, which block light from reaching submerged aquatic vegetation and decrease oxygen levels. Low or no oxygen creates "dead zones" where marine life cannot survive
  • Most importantly, trees produce the oxygen we breathe

Forests create habitat:

  • Forests provide food, shelter, nesting sites, and safe migration paths for critters in the water and on land
  • "Interior" forests, or those that are not near any forest edge or other land use provide dwelling spaces with moderate temperatures and light levels
    • Only 40% of Chesapeake forests are considered interior habitat
  • Streamside forests shade the waters that run beneath their leafy canopies, maintaining cooler water temperatures and reducing stress on sensitive fish
    • The leaves and other plant materials that fall into the water create a nice habitat for underwater critters
  • Standing dead trees provide habitat to owls, woodpeckers, squirrels, and other animals that nest in tree cavities
    • Many insects, small mammals, and birds can be found foraging and living among the decomposing logs, stumps, and leaves on the forest floor


Rivers & Streams

Streams and rivers not only provide the Chesapeake Bay with its fresh water, they also provide many aquatic species with a critical habitat. Fish, invertebratesm amphibians, and other wildlife species all depend on the Bay's tributaries for survival.

When the Chesapeake's streams and rivers are in poor health, so is the Bay, and the wide array of wildlife it harbors is put in danger.

There are hundreds of thousands of streams, creeks, and rivers throughout the Chesapeake Bay watershed that eventually flow to the Bay. These freshwater tributaries provide critical habitat for many plants and animals.

Fish that spend their entire lives in freshwater:

  • Catfish
  • Sunfish
  • Brook trout

Fish that travel from the Bay to the ocean to freshwater streams to spawn:

  • Shad
  • Atlantic sturgeon
  • Striped Bass

Fish are not the only creatures that live in rivers and streams. There are many invertebrates such as worms, clams, and other shellfish. There are also many plant and amphibian species.

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Aquatic Reefs & Pilings

  • Aquatic reefs are complex and diverse communities made up of densely packed oysters

    • Hundreds of aquatic animals find food and shelter in oyster reefs. They have many nooks and crannies that provide a safe haven for small fish and invertebrates to hide from predators

    • Larger species, including white perch, striped bass, and blue crabs, visit reefs to breed and find food

  • Reefs are the largest source of hard surface on the Bay's bottom, which is usually covered with soft sediment

    • Oyster larve, sponges, and barnaclesa are just a few of the many invertebrates that live attached to hard surfaces

  • The other hard surfaces in the Bay are piers, rocks, jetties, and pilings

    • These surfaces provide hard surfaces for invertabrates


Beaches & Tidal Flats

  • Sandy beaches and tidal mud flats line thousands of miles of Chesapeake Bay shoreline

    • Beaches are usually found along the lower Bay

    • Mud flats are more common in the upper Bay

  • Beaches are harsh environments where wildlife are subject to wind, waves, and heat

  • Beaches and tidal flats support a wide variety of plants and animals, including birds, mammals, insects, and invertebrates

    • Sandpipers and small crabs scurry along the water's edge

    • Gulls and terns fly above

    • Underneath the sand and mud, worms, clams, and crabs burrow to avoid predators

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Marshes & Wetlands

  • Wetlands are transitional areas between land and water

  • Marshes are a type of tidal wetland along the shoreline where aquatic grasses and sedges grow

  • Hundreds of species of fish, birds, mammals, reptiles, and invertebrates depend on marshes and wetlands for food

    • Thousands of aquatic species-- including worms, periwinkles, insects and ribbed mussels thrive in wetlands

    • In turn, larger animals eat these smaller species

  • Marshes and wetlands provide shelter for a variety of animals

  • 2/3 of the nations commercial fish and shellfish depend on wetlands as nursery or spawning areas

  • Large flocks of waterfowl visit wetlands during their winter migrations to feed and rest

  • Mammals such as muskrats and beavers build their homes in wetlands


Open & Shallow Waters

  • Shallows

    • Along the shores of the Chesapeake Bay is an area of incredible biological activity: the shallows

      • The shallows extend from the shore to about 10 feet deep

      • Beyond the shoreline are the open waters of the Bay - with channels up to 100 feet deep

    • Many small fish seek refuge from predators in shallow waters

      • Larger fish and birds hunt for prey there

    • Bay grass beds are a critically important part of the shallows

      • They provide shelter for blue crabs, young fish, and sharks to hide from predators

  • Open waters

    • Provide a haven for migratory fish such as blue fish, cobia, and mackerels

      • Migratory fish visit the Bay in the summer to feast on menhaden, anchovies, and other small fish and invertebrates

    • Microscopic plankton float through open waters, forming the base of the Bay's food web

  • In summer, both the shallows and open waters become very warm, making them susceptible to algae blooms

    • Algae blooms can lead to low-oxygen "dead zones" that suffocate underwater life

  • In winter, animals that dwell in the shallows generally retreate to deeper, warmer waters

    • Hundreds of thousands of migratory birds stop on the Chesapeake's open waters to rest and feed

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Last updated: December 14, 2018

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