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Coastal Waters Management

Coastal Waters Management

Americans love the seashore and the water. Nearly half of all the construction in the United States since the 1970s has been on the seacoast. By the year 2000, 80 percent of Americans lived an hour's drive or less from the seashore. The National Oceanic and Atmospheric Administration, the primary federal agency responsible for managing the oceans, has projected that by 2010 half of all Americans will be living in coastal counties. Globally almost two-thirds of the world's largest cities are coastal. Sixty percent of people on Earth live within 97 kilometers (60 miles) of the sea.

The reasons why so many humans are coastal dwellers are that coastal areas and oceans have provided a large part of the food that people eat, and have served as the major transportation highways long before there were adequate roads, railroads, or airplanes. The coasts are desirable places to live, offering recreational opportunities such as swimming, boating, fishing, snorkeling, and diving. Coastal areas also are home to marine mammals and other sea life, and can be rich in minerals and other energy sources.

The Need for Coastal Management

This massive habitation at and growing migration to the ocean's edge has brought with it serious side effects. More people have increased the need for infrastructure such as roads, sewers, sewage treatment facilities, bridges, fresh-water sources, and solid waste (garbage) disposal. The increased human activity has strained the ability of nature to replenish and clean itself. Therefore, Americans have gradually established regulations to guide how the seashore is developed and how coastal waters are managed. The three major water resources to examine are (1) the ocean itself, (2) brackish waters, and (3) fresh waters.


The ocean itself is often considered the planet's most vital ecosystem for making life possible. Oceans comprise 97 percent by volume of all the Earth's living space for plants, animals, and humans. The oceans contain vast living and nonliving resources. Reefs, beaches, and other areas are among the ocean environments directly affected by the quality and temperature of the water. Moreover, coastal areas have served as the entry and exit point for what has always been and still is the major mode of commercial transportation: marine shipping.

Ocean temperatures and the flow of currents are vitally important in regulating climate. Many scientists have shown that the rising temperature of the oceans could be contributing to global warming . In addition, warming temperatures may cause polar ice to melt, which would raise the level of the oceans and cause vast flooding in the heavily populated seaside areas.

The ground under oceans, especially near coastal areas, contains enormous oil and gas resources. As easy and ample supplies of these hydrocarbons so necessary for an energy-intensive economy and society such as the United States become scarce, pressure increases to commercialize these suboceanic sources of energy.

Drilling for, pumping, and transporting ocean-based oil and gas resources to onshore refineries without creating serious damage to the water and marine life is a delicate process. Both federal and state laws regulating offshore drilling are constantly being reexamined. The interests of oil companies, electric power-generating plants, consumers who enjoy affordable energy, and environmentalists can sometimes collide.

Brackish Waters.

Rivers and their coastal estuaries supply coastal areas with brackish water. Estuaries are extremely important habitats for a wide variety of animal and plant life. Turtles, fish, crabs, clams, mussels, and other sea life (including coastal mammals) all benefit from healthy estuaries and other coastal wetlands that often are the nurseries for young animals.

Coastal wetlands and marshes also act as sponges and filters, retaining water and slowing or preventing it from rushing uncontrollably downstream, which would produce erosion. These wetlands also slowly filter out sediments and chemical contaminants that otherwise would reach the ocean.

Development as well as contamination from pesticides and herbicides, industrial pollutants, sewage spills, and other sources of pollution are degrading the quality of coastal ecosystems. For example, in the 1990s a huge area deemed the "Dead Zone" was discovered in the Gulf of Mexico at the mouth of the Mississippi River. This area, covering 12,800 square kilometers (5,000 square miles), is almost devoid of any life as a result of runoff containing nitrates (a component of some fertilizers), pesticides, herbicides, and other chemicals from farms and industries upriver. The Dead Zone threatens fish, shrimp, and other commercial seafood, as well as recreational fishing, and is a potential risk to tourism.

Fresh Waters.

Construction and intensive development are threatening fresh groundwater that is especially vulnerable at sea level. Streams, springs, and aquifers easily can be contaminated by runoff from streets and parking lots. Fresh-water issues also include proper management of the Great Lakes, which are considered part of the coastal zones of the United States because of their vast sizes.

One of the most serious fresh-water problems is infiltration by sea (salt) water, often known as salt-water intrusion. Fresh water is in short supply in most areas of the United States, but it is especially precious in coastal zones because of the demand for fresh water for drinking, cooking, bathing, irrigation of crops and lawns, and industrial uses. In April 2001, for example, the state of Florida asked for a waiver of federal law, which would allow the state to pump untreated rainwater into underground aquifers that were being depleted at rates much faster than natural seepage could replace them.

Coastal Zone Management Act

In order to protect the salt-water and fresh-water resources of the American coastal areas described above, numerous federal laws have been enacted. The most important is the Coastal Zone Management Act (CZMA) of 1972. This law resulted from several studies that showed extensive pollution of the nation's estuaries and that recommended action to clean these up. The legislation also was the result of a growing awareness of environmental problems in the United States, and active pressure from environmental groups such as the Sierra Club, the Audubon Society, and groups such as the Friends of the Earth and the Natural Resources Defense Council.

The CZMA provides for a wide range of programs and regulations of which the following are the most significant:

  • Protection of the estuaries and coastal wetlands;
  • Protection of beaches, dunes, bluffs, and rocky shores;
  • Regulation of seaport development; and
  • Redevelopment of urban ports.

Today over 97 percent of the U.S. shoreline is under the CZMA program.

Over the years, the CZMA has been strengthened and expanded. Moreover, additional specialized laws and regulations have been enacted that extend the management of water and coastal resources. The objective of these laws directed at the waters and lands along the seacoast is to lay out a strategic land-use policy that will protect coastal water resources and beaches. The objective of land-use policy is to achieve sustainable development of these coastal resources; that is, using them so that they do not deteriorate but instead have a chance to replenish themselves for future generations.

Clearly, coastal water management is a vitally important process for the future prosperity, continued enjoyment, and effective economic use of oceans, beaches, seashores, and coastal waters.

see also Artificial Recharge; Balancing Diverse Interests; Coastal Ocean; Estuaries; Land-Use Planning; Mineral Resources from the Ocean; National Oceanic and Atmospheric Administration; Ocean Health, Assessing; Petroleum from the Ocean; Pollution of Groundwater; Pollution of Lakes and Streams; Pollution of the Ocean by Plastic and Trash; Ports and Harbors; Transportation.

Steffen W. Schmidt


Barker, Rodney. And the Waters Turned to Blood: The Ultimate Biological Threat. New York: Simon & Schuster, 1997.

Cicin-Sain, Biliana, and Robert W. Knecht The Future of U.S. Ocean Policy: Choices for the New Century. Washington, D.C.: Island Press, 2000.

Dean, Cornelia. Against the Tide. New York: Columbia University Press, 1999.

Internet Resources

Celebrating 30 Years of the Coastal Zone Management Act. Office of Ocean and Coastal Resource Management, National Ocean Service, National Oceanic and Atmospheric Administration. <>.

EPA Action Plan for Beaches and Recreational Waters. U.S. Environmental Protection Agency. <>.

Gulf of Mexico Hypoxia Assessment. National Ocean Service. <>.

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Coastal Ecosystems

Coastal Ecosystems

An ecosystem is an interacting community of organisms and their non-living physical environment occupying a certain place and time. Coastal ecosystems occupy the margins of the land and the sea. There are many different types: salt marshes, mangrove swamps, sand dunes, seagrass meadows, coral reefs, kelp forests, tidal flats, rocky intertidal , maritime forests, and coastal heathlands. All are heavily influenced by some combination of saltwater, ocean waves, currents, and ocean breezes, though not necessarily all of these.

Components of Coastal Ecosystems

The major interactions of organisms and their environment in coastal ecosystems include energy transfer and cycling of materials. These involve several functional groups of organisms. Plants and algae are the major primary producers, that is, organisms that produce their own food through the process of photosynthesis. They use the energy from the sun and the nutrients washed down to the coast from the surrounding land or brought to the coast by the ocean.

The plants living in constant or periodic contact with ocean water are called halophytes ("salt plants"). They must have special adaptations to be able to thrive because saltwater is toxic to most plants.

Plants and algae are the bases of the coastal food chain. They may be consumed by herbivores , such as insects or geese that feed on salt marsh grasses, snails that consume seaweeds on rocky shores, or fish that graze on tropical seagrass beds. Except for the intertidal marshes and mangrove swamps, the place of insects in coastal ecosystems is minor, their ecological role being replaced by crustaceans (such as crabs, shrimp, lobsters, and beach fleas) and mollusks (snails, clams, mussels, etc.) All these, in turn, may become food for carnivores, such as birds (shorebirds, waterfowl, hawks, etc.) or fish. Many animals living in coastal ecosystems do not feed directly on plants or other animals but feed on detritus , nonliving plant material that may contain a large amount of bacteria and fungi. The bacteria and fungi that colonize particles of detritus act to break down this material to simple chemical compounds that can be recycled.

Coastal versus Terrestrial Ecosystems

Coastal ecosystems differ from terrestrial ones in several significant ways. The ocean contributes to the exchange of materials, bringing nutrients and removing waste products. In terrestrial ecosystems, the exchange of materials between organisms and their environment does not involve this major mediating agent.

The dominant types of producer organisms in terrestrial ecosystems are plants. In coastal ecosystems they include plants, macroalgae (seaweeds), and phytoplankton (unicellular algae). Seaweeds reach their greatest level of diversity and productivity in coastal ecosystems.


An estuary is a semienclosed body of water where freshwater meets the sea. Typically located at the mouth of rivers, estuaries have characteristics of both fresh and marine habitats and serve as a vital ecological link between the two realms. One of the major factors that determines the place where different organisms can live within an estuary is the gradient of salt concentration, that is, the salinity. The upper reaches of the estuary are most influenced by the river and therefore may be almost completely freshwater. As one moves downstream the influence of the sea becomes increasingly dominant. The salinity of the water gradually increases until at the mouth of the estuary, it is similar to that of the surrounding coastal ocean.

There are daily changes in the movement of water and the salinity profile within an estuary. At high tide the estuary is flooded with higher salinity seawater, and at low tide the river water may dominate and the flow is in a downstream direction. Seasonal changes in response to times when greater rainfall and snowmelt wash down the rivers also strongly influence the estuary.

Another characteristic of estuaries is the salt wedge. Since saltwater is more dense than freshwater, the saltwater tends to underlie the river water where the two meet. Thus the surface water of the estuary is usually much fresher than that at the bottom.

These changes in salt concentration within the estuary present a real challenge to plants and animals. They not only have to be salt tolerant, but they also have to be able to tolerate changes in salinity, thus estuaries have their own unique species that differ from those of wholly freshwater or marine habitats. Those few plants that have been able to adapt to life in the estuaries, such as seagrasses, salt marsh plants, and different types of algae, are often extremely productive because having adapted to tolerate the stresses of changing salinities, growing conditions are ideal. Intertidal plants, such as salt marsh grasses and mangrove trees, submerged sea grasses, and algae, are constantly moist with a steady supply of nutrients coming from the sea or the river. As a result, estuaries are among the most productive ecosystems on Earth in terms of the amount of organic matter produced by plants and algae. Estuaries are home to abundant fish, bird, and invertebrate populations, which take advantage of this tremendous plant and algal productivity. Many species of ocean fishes, including a number that are commercially important, spend their juvenile stages in the relative safety of estuaries where the abundance of life sustains their growth to adulthood.

Located at the end points of watersheds, estuaries are often sites where pollutants accumulate and thus the estuaries are very sensitive to human activities. Pollutants generated in the watershed and transported downstream by rivers tend to settle out once they reach estuaries. Thus estuaries serve as barometers of the health of entire watersheds.

Coastal Dunes

Coastal dunes are an unstable, shifting habitat whose very structure is a product of ocean currents, winds, and storms. Currents and waves along the shore deposit sand on the beach, then winds shape the sand into series of small hills that often gradually migrate inland to be constantly replaced at the beachfront by new dunes. Winter storms may completely reshape the landscape, blowing holes in the dunes closest to the ocean and starting the process over.

Sand is unstable, which is why dunes can achieve a maximum stature of only several hundred feet. Dune plants have to be able to tolerate life in shifting sands where water rapidly percolates through the soil and out of the reach of plant roots. Plants that grow on sand dunes must be able to tolerate harsh, desert-like conditions where, as any beachgoer who has walked barefoot on hot sand will attest, there is no shade and daytime temperatures can be extremely hot. Dune plants have a lot in common with desert plants, in which fresh water loss and overheating are real problems. Thus many are succulent or have thick cuticles on their leaves and deeply sunken stomata to prevent water loss. These same kind of adaptations are found in cacti and other desert plants.

The roots of some dune plants play a role in stabilizing sand dunes, helping to shape the nature of this ecosystem. Beach grass is particularly notable in this regard and is often planted deliberately by people to keep dunes in place. The rapidly growing network of roots produced by beach grass penetrates deep into the dune, lending structural support that can keep the dune in place except under the most severe coastal storms. Beach naupaka, a shrub, is valued the same way on Hawaii and other Pacific islands. A dune initially covered by these stabilizing plants is ripe for colonization by other plants, thus the original plant colonizers set the stage for a successional cycle.

see also Aquatic Ecosystems; Halophytes.

Robert Buchsbaum


Bertness, Mark. The Ecology of Atlantic Shorelines. Sunderland, MA: Sinauer Associates, 1999.

Carson, Rachel. The Edge of the Sea. Boston: Houghton-Mifflin, 1979.

Teal, John, and Mildred Teal. Life and Death of the Salt Marsh. Boston: Little Brown, 1969.

Valiela, Ivan. Marine Ecological Processes, 2nd ed. New York: Springer-Verlag, 1995.

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