Estuaries are found in coastal environments around the world. They are partially enclosed bodies of water that are open to the sea, often forming at the tidal mouth of a river. Usually, they contain what is known as “brackish” water, a combination of salt water from the ocean and fresh water from the river. Two examples of large estuaries are Chesapeake Bay and Puget Sound.
The brackish water of an estuary is a unique environment. It gathers nutrients from the land and ocean, and contains an abundant variety of life. Estuaries provide the habitat for over 75 percent of the commercial fish catch for the United States. They are homes for shore and sea birds, crabs and lobsters, clams and other shellfish, raccoons, opossums and many reptiles. Many species of fish lay their eggs in estuaries. Marine mammals that usually live in the ocean, such as beluga whales, use estuaries for calving during the summer.
While they are an important habitat for fish, animals and birds, estuaries also play another important role in the environment. They help to control pollution. Water from upland areas often carries pollutants and sediment. Marshes and plant life in estuaries act as a filter to remove these pollutants from the water. Estuaries also help to control erosion and reduce flooding of the mainland. They soak up heavy rain and storm surges and reduce the impact of high winds that move in from the ocean.
But estuaries are in danger. The development of coastal land for human use creates many problems for the estuarine ecosystem. Since legal restrictions on wetland development are fairly recent, many estuaries have already been destroyed by human activity. In a Restore America’s Estuaries (RAE) newsletter, Harry Lester talks about the loss of his favorite oysters, the Lynnhavens, also the favorites of New York tycoons and British royalty. The oysters, which nearly became extinct, were victims of pollution, over-harvesting, sewage and development along the Lynnhaven River. Lester, a prominent Virginia Beach commercial real estate developer, says, “I realize I was part of the problem.”
Global warming, which causes sea levels to rise, also threatens estuaries. Along with storms, global warming causes North Carolina wetlands to erode at a rate of about 800 acres per year. Estuaries can also suffer from an excess of nutrients such as nitrogen and phosphorus. These nutrients are deposited in estuaries from sewage treatment plants, fertilizers, septic systems and polluted air. When the levels of the nutrients become too elevated, overgrowths of algae can occur, known as algal blooms. One example of this is the pfiesteria outbreaks in Chesapeake Bay. This potentially toxic microorganism can cause massive fish kills along the coasts.
Because of the many benefits that are provided to mankind by estuaries, they are well worth preserving and restoring. Estuaries are important to the food supply. A healthy estuary produces more food per acre than the richest Midwestern farmland. Estuaries are important for quality of life. They provide scenic beauty and recreational opportunities. They are important to the economy because they benefit tourism.
Congress created the National Estuarine Research Reserve System (NERRS) in 1972 to protect a system of estuaries that represents the range of coastal estuarine habitats in the United States and its territories. This system protects more than one million acres of estuarine land and water in 17 states and in Puerto Rico. But all estuaries, whether or not they are in the NERR system, are protected under every U.S. state’s coastal zone management program.
In addition to legislation for the protection of estuaries, there are also laws and organizations to promote their restoration. The Estuary Restoration Act (ERA) was passed into law in 2000 and modified in 2007 to promote a coordinated federal approach to estuary habitat restoration. The National Oceanic and Atmospheric Administration (NOAA) is one of the member agencies creating protocols and conducting monitoring for the Act to track the progress of the restoration. One of the goals of the ERA was to restore one million acres of estuarine habitat by the year 2010.
Like the Grand Canyon and Yellowstone National Park, estuaries are among America’s national treasures. They are places where humans can go to reconnect with nature: to fish, swim, relax and experience the balance and intelligence of a natural environment. They are nurseries for wildlife and for human souls.