Chesapeake Bay Watershed Habitat and Ecosystem

The Largest Estuary a Complex and Troubled Environment

Sep 15, 2008

The estuary ecosystem, where ocean saltwater and inland freshwater meet, is large but shallow. A heavy load of nutrients are washing into the bay and fouling the habitat.

The 64,000 square mile Chesapeake Bay watershed drains all of the water that falls from the sky and springs from the earth and rolls downhill along streams, creeks, and rivers and flow through parts of New York, Pennsylvania, Delaware, Maryland, Virginia, and the District of Columbia on its way to the Atlantic Ocean. The complexities of soil and air add to the web of interdependencies that make up the ecological system. Humans play an important role in its health.

By the Numbers

About 100,000 streams and rivers flow into the largest estuary in the United States along its 200-mile length. The Bay is 3.4 miles across at its narrowest point in Aberdeen, Maryland, and 35 miles across near its mouth in southeastern Virginia. It has 11,600 miles of shoreline encircling 15 trillion gallons of water. The Bay's average depth is 21 feet.

The shoreline and wetlands are perhaps the most attractive feature to the more than 15 million people who call the watershed home. The Chesapeake Bay watershed population is expected to climb to 18 million people by the year 2020.

But approximately 3,600 other species also make their home in and around the Bay. Of these, 265 species are fish and 29 species are waterfowl.

What’s the Matter with the Bay?

Unfortunately, the Chesapeake Bay is in trouble. The living resource has been impacted by human activity. Centuries of overharvesting of fish and shellfish have upset the system of checks and balances that once ensured a health place for all to live. When species were brought in to the Chesapeake Bay from other parts of the world to provide for the seafood industry, problems arose because the new species had no natural enemies to keep them in check. Disease resulted and oysters, in particular, suffered steep declines from which they have not recovered.

The human population explosion around the Bay and increased industrial, urban, and recreational activities are filling the waterways with pollution from chemicals, sewage, and just plain dirt. Erosion sends sediment into the Bay and this is a huge concern. Sunlight cannot penetrate the murkiness and little can grow in the cloudy water.

Nutrient Pollution

Of key concern to scientists is the impact of nutrient pollution. This occurs when nitrogen and phosphorus from human and pet waste, farms, fertilizer, household chemicals, and more is pumped into the Bay from sewage treatment plants or washes off of fields, lawns, and pavement. The nutrients cause algae to grow just as nutrients in fertilizer help crops and lawns grow. The abundant alga dies, of course, and sinks to the bottom of waterways where it uses oxygen in its decomposition process. When plants use most of the oxygen, there is little left for animals like the Chesapeake Bay’s signature Blue Crabs.

The oxygen-starved areas are called dead zones. Scientists have noted that dead zones in the Chesapeake Bay, the Gulf of Mexico, and other coastal areas are growing and that this is an ecological time bomb.

Why Should We Care about the Chesapeake Bay?

Many people don’t see themselves as part of the natural ecosystem because they live inside building, don’t grow their own food, and are insulated from nature by heating and air conditioning systems. When asked to consider that they are intricately linked to the well being of living and non-living things, most realize that ecosystem health in places like the Chesapeake Bay is related to their own physical and social fitness.

The Chesapeake Bay is a resource that touches on the economic and emotional health of many in the region. The challenge presented by the current condition of the Bay is a challenge that cannot be ignored. The Chesapeake Bay's troubles are not unfamiliar to those who live in coastal environments worldwide.