Coastal Zones

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Coastal Zones


Coastal regions are regions where water bodies, in particular oceans and lakes border land. As one progresses from land toward water, various coastal zones exist, each with particular ecological niches. In general, coastal zones include the splash zone, the high intertidal zone, the low intertidal zone, and the low tide zone.

Coastal zones are extremely sensitive to environmental perturbations. The various zones are defined by the physical components within the zone. Changes to these physical properties because of human activity affect the community structure within the zone. Human and natural threats to coastal zones include extreme weather, rising sea levels, agricultural runoff, invasive species, and overfishing.

Historical Background and Scientific Foundations

As one moves from land toward water along a coast, the habitat changes from one which is mostly terrestrial with occasional splashes of water to one which is mostly aquatic with rare events of exposure to air. This variability creates a multitude of habitats in which animals and plants with different ecological needs can exist. The animals and plants that live along coastlines have developed numerous adaptations to withstand the changing environment. For example, snails that require air might be found in the splash and the high tide zones where they are less often exposed to water. During those times they are exposed to water, they can close the trap door or operculum that seals them inside their shell to wait until conditions are more favorable. On the other hand, mollusks like clams and mussels extract dissolved oxygen from water and live beyond the high tide zone where they are often submerged. During events when the tide recedes, clams and mussels can seal the two sides of their shells together to withstand exposure to air.

The diversity of habitat that determines the coastal zones is due in large part to tidal action. The moon, and to a lesser extent the sun, exert a gravitational pull on water bodies. This pull results in high tides during which the water impinges greatly onto the land and low tides when the water recedes. In some places there is one high tide and one low tide per day. In other places there are two high tides and two low tides per day. In addition, the height on the land that the high tide reaches varies from day to day, as does the height of the low tide. The relative location of the moon and sun as well as the size of the water body and the topology of the coastline determine the size and timing of the tides. The part of the shore that is bounded by the high and low tides is sometimes called the littoral region.

The splash zone is the region of the shore farthest from the water. Wave action throws splashes of water into this region, but it only covered with water during extreme events such as an extreme tide or a flood. Compared to other coastal zones, the splash zone has few permanent inhabitants. Because the splash zone is usually dry and only occasionally wet, moisture and temperature can be variable. Salts that remain after water evaporates can make the soil or substrate in a splash zone extremely saline. Some beach grasses are particularly adapted to growing in saline soils and they are often found in splash zones. Inhabitants also include animals with tough coverings to protect against fluctuations in moisture and salinity such as crabs and snails.

The high intertidal zone is the region of the shore that is only completely covered with water during the higher high tides. This region is exposed to the air more often than it is covered with water. The organisms that live in this zone are subject to great pressures from waves and most of them have developed adaptations that allow them to hold on to substrates. Mussels excrete strong threadlike strands that fasten them to rocky surfaces. Sea anemones have extremely muscular feet that hold strongly to rocks and other hard surfaces. Mollusks called limpets have created a suction with their foot that holds them to the substrate. The dominant photosynthetic organism in high intertidal zones is usually kelp, which use strong rootlike holdfasts to secure themselves to the substrate.

The middle intertidal zone is the region of the shore between the location of the average high tide and the location of the average low tide. This zone is covered with water part of the time and exposed to air part of the time. More types of organisms live in the middle inter-tidal zone than in either of the zones that are farther from the water. The middle intertidal is the place where the most densely populated tide pools are found along rocky shores. Within tide pools there is often competition for space among animals and plants that are attached to rocks. Organisms that are often found in middle intertidal zones in marine environments include crabs, anemones, sea stars, barnacles, mussels, clams, and kelp.

The low intertidal zone is the region that is nearly always submerged except during extremely low tides. The nearly continuous flow of water over this zone brings nutrients to plants and algae. The movement of water also brings significant quantities of plankton to animals that filter food out of the water using tentacles or siphons. These animals include tube worms, anemones, soft corals, clams, and barnacles. Grazers, animals the consume plants and phytoplankton, also frequent this zone, feeding on the carpets of algae and kelp. Fish and other swimmers are part of the low intertidal community, consuming algae, filter feeders, and grazers. Low intertidal regions tend to be places of high biological diversity.

Impacts and Issues

Coastal zones are extremely sensitive to environmental perturbations. The physical structure within each of the zones is extremely important, providing specific environmental niches for the community of organisms that reside in a zone. Changes to these physical properties necessarily affect the ecology. Some of the impacts that affect the physical structure of coastal zones include extreme weather, rising sea levels, and agricultural runoff. Similarly, changes to the biological structure, such as an invasive species establishing a population or overfishing, affect the ecological dynamics in coastal zones.

Weather is a major factor impacting all of the coastal zones. Storms enhance the already powerful pounding of waves against the shore. This can modify the physical structure by breaking rock down or redistributing sediments. Heavy rainfall can change the substrate by


ECOLOGICAL: Having to do with interactions among organisms.

NICHE: A term describing a species habitat, range of physical and biological conditions, and relationships within its ecosystem.

TIDE: The changing surface level of a large body of water such as the ocean or a lake that results from changes in the gravitational pull on the water by the Moon and the Sun.

depositing or removing sediments. Powerful wave action can also dislodge many sessile organisms from the substrate to which they are attached.

Extreme storms can lead to flooding, submerging the splash zone and high intertidal zone for long periods of time. Few organisms living in these zones can withstand extended periods of flood. Alternatively, droughts can cause lake waters to recede, exposing low intertidal areas to the air for extended periods of time. Organisms in these zones are unable to withstand such exposure.

Climate change is a significant threat to coastal zones. In the same way that extreme storms can inundate the splash zone and high intertidal zone with water for unusually long periods of time, climate change is expected to lead to a rising sea level. Coastal zones are obviously the area that will be most impacted by such a change. Splash zones will become intertidal zones and high intertidal zones will become submerged. This will cause a major disruption to coastal ecosystems throughout the world.

Farms use high concentrations of fertilizers to improve crop production. When rainwater carries these fertilizers into the oceans and lakes, they act as an overdose of nutrients, stimulating algal blooms and secondarily bacterial blooms. Bacterial metabolism removes oxygen from the water. Animals that require oxygen may be threatened or unable to live in these zones, known as dead zones. The largest dead zone in the world is an area of more than 22,000 square mi (56,980 square km) located where the Mississippi River empties into the Gulf of Mexico.

Invasive species can have significant impact on coastal zones. When exotic species become established in a coastal environment, the impacts can be enormous. One of the most disruptive invasive species affected coastal zones in the Great Lakes. The zebra mussel, a native of Russia, is thought to have been brought to the United States in ships’ ballast water. These fast-growing mussels displaced the native species of quagga mussel and changed the ecology of the Great Lakes’ coastal

zones. In addition, the zebra mussels caused economic damage to ships, harbors, and water treatment plants.

Overfishing is another negative environmental impact on coastal ecosystems. When fish populations decline because too many are removed by commercial and recreational fishermen, the ecosystem can become unstable. Just as when the species composition is changed because of habitat degradation, overfishing can change the structure of the food web and the balance of competition between species. In addition, it may open up habitat for invasive species.

The United States has enacted numerous policies and regulations that oversee development and use of the land and water affecting coastal zones. These include the Clean Water Act, the Coastal Zone Conservation Act, the Marine Mammal Protection Act, and the Endangered Species Act.

Primary Source Connection

Renewable energy is energy that can be obtained from almost inexhaustible sources such as ocean tides, wind harvesting, geothermal sources, and natural sunlight. The potential of these sources is a vast unlimited source of energy for future generations. Basic technology for this purpose already exists in the United States. Since the beginning of the new millennium, various individuals and companies in the United States have expressed willingness to explore unconventional means of generating energy. It is for these reasons that experts have been advocating the use of renewable energy as a source of electricity. In the past, the U.S. government has also thought in this direction.

The Coastal Zone Renewable Energy Act of 2003 is a bill that significantly explores this possibility. Originally tabled in the first session of the 108th Congress on March 11, 2003, it proposes to zone coastal areas for the production of energy from renewable resources. The bill also proposes the use of renewable energy sources such as wind, tidal, geo-thermal, hydropower, biomass energy, and the like. Unlike fossil fuels, the availability of these resources is virtually bottomless, but the amount of energy that can be obtained from these resources is restricted to their immediate availability.



1st Session

H. R. 1183

To promote the Sensible Development of Renewable Energy in the Waters of the Coastal Zone, and for other purposes.


March 11, 2003

Mr. DELAHUNT (for himself and Mr.SAXTON) introduced the following bill; whichwas referred to the Committee on Resources


To promote the Sensible Development ofRenewable Energy in the Waters of the CoastalZone, and for other purposes.

Be it enacted by the Senate and House ofRepresentatives of the United States of Americain Congress assembled,


This Act may be cited as the “Coastal Zone Renewable Energy Promotion Act of 2003.”


(a) FINDINGS—The Congress finds that—

  1. There is an increasing need for the production of electricity from energy facilities that use renewable resources and some of these facilities may be located in waters under the jurisdiction of the United States, including the coastal zone;
  2. Energy companies have already sought to construct energy facilities in State and Federal waters that will use renewable wind energy resources;
  3. Nationwide there are more than 50 proposals to construct and operate ‘wind farms’ for producing electricity in State and Federal waters, and some of these proposals include anchoring more than five hundred wind towers to the ocean seabed within sight of land;
  4. Existing Federal and State law does not provide a process to address the unique issues raised by proposals to locate energy facilities for renewable resources in the marine environment, thereby hindering or jeopardizing sensible development of these renewable energy resources; and
  5. New Federal and State policies are needed to ensure the timely and sensible development of renewable energy resources that are accessible in the marine environment and to provide a mechanism to resolve the significant public trust issues involved in resource allocation and multiple uses in the marine environment.

(b) PURPOSES AND OBJECTIVES—The purposes and objectives of this Act are to—

  1. promote the sensible development of energy facilities that use renewable energy resources in the marine environment by authorizing the Secretary of Commerce to establish a licensing regime and permitting process to ensure due consideration of the public trust issues involved in resource allocation, multiple use, and impacts on the marine environment;
  2. direct the Secretary of Commerce, acting through the Administrator of the National Oceanic and Atmospheric Administration (NOAA), to use NOAA’s expertise about the marine environment and coastal zone to develop new Federal rules and regulations to authorize and govern the sensible development of renewable energy resources in a manner that provides for public safety, safe navigation, protection of the marine environment, prevention of waste, conservation of natural resources, access to important commercial and recreational fishing areas, the protection of correlative rights, protection of national security interests, and payments to the Federal Government for constructing and operating renewable energy facilities in waters under the jurisdiction of the United States seaward of the coastal zone; and
  3. encourage coastal States to amend their coastal zone management plans to include policies and procedures that address (A) issues arising from the location in the marine environment of energy facilities that utilize renewable energy sources; (B) conflicting and competing resource allocation and multiple use issues; and (C) any adverse impacts from such facilities on the marine environment, commercial and recreational fishing and other activities, the boating community and aesthetic, cultural and historic values.



Section 309 of the Coastal Zone Management Act of 1972 (16 U.S.C. 1456b) is amended—

(1) in subsection (a) by inserting at the end the following new paragraph—

(8) The procedures and enforceable policies adopted to facilitate the location of renewable energy facilities in the marine environment, including any wind energy facility, shall, among other things—

(A) identify priority locations for renewable energy facilities in the coastal zone;

(B) ensure continued access to commercial and recreational fishing areas, including shellfish beds;

(C) include an environmental review of the potential impacts on—(i) marine mammals and endangered species and their designated critical habitat; (ii) birds; (iii) the marine environment including the seabed; (iv) aesthetic, cultural and historical resource values; and (v) the cumulative impacts of multiple renewable energy facilities;

(D) evaluate navigational and public safety concerns, including but not limited to aviation safety, and ensure continued access to important traditional recreational boating areas;

(E) include obligations for the payment of funds necessary to pay for the decommissioning and removal of renewable energy facilities;

(F) include an assessment of the need for the energy produced by renewable energy facilities; and

(G) take into account national security interests.

(2) in subsection (c) by inserting at the end the following new sentence: ‘In making funding decisions, the Secretary shall give special consideration to those proposals for management program changes related to the implementation of the objectives identified in paragraph (a)(8) in States with pending renewable energy facility proposals.



The Coastal Zone Management Act of 1972 (16 U.S.C. 1451 et seq.) is amended by adding at the end the following new section—


(a) LICENSE REQUIREMENT—No person may construct or operate a renewable energy facility in waters under the jurisdiction of the United States seaward of the coastal zone except in accordance with a license issued pursuant to this section.

(b) Letter of Intent, Public Notice and Request for Proposals—

(1) Any person who seeks to apply for a license under this section shall notify the Secretary in writing of their intent to apply for a license under this section. A letter of intent shall include, at a minimum, a description of the proposed renewable energy facility, the specific location where the applicant proposes to construct the facility, the proposed timeframe for construction and operation of the facility and the names of the applicant, owners and operators of the proposed facility.

(2) Within 30 days of receipt of a letter of intent, the Secretary shall publish in the Federal Register notice containing the requirements for a license application in the area identified in the notice issued under paragraph (2), and a request for proposals from all persons who seek a license to construct and operate a renewable energy facility in the same location. The Secretary shall determine the time within which proposals must be submitted, but shall not set the submission date less than 60 days from the date notice is published in the Federal Register.

(c) PUBLIC INTEREST EVALUATION—In evaluating applications received under this section, the Secretary shall consider the amount of energy the proposed project will produce, the economic impact to the region where the facility will be located, the environmental impacts of the proposed facility, the displacement of competing uses of the proposed site and other relevant factors to determine which proposed project best serves the public interest.

(d) LICENSE ISSUANCE PREREQUISITES— The Secretary may only issue a license under this section after the Secretary determines that—

  1. based on recommendations from the Secretary of Defense, the facility will be consistent with national security needs;
  2. based on recommendations from the Corps of Engineers and the Coast Guard, the facility will not create an obstruction to navigation;
  3. the application is consistent with the approved management programs of affected states;
  4. construction or operation of the facility will not unduly restrict access to commercial and recreational fishing areas, including shellfish beds, and recreational boating areas;
  5. the facility will not adversely affect marine mammals, threatened or endangered species, migratory birds, or designated critical habitat;
  6. construction or operation of the facility will not adversely affect aesthetic, cultural, or historical resources recognized or protected under Federal law or the laws of the affected coastal States;
  7. after consultation with the Secretary of Transportation, that the renewable energy facility does not pose a threat to aviation safety;
  8. as a result of the Environmental Impact Statement, the facility can be constructed or operated in a manner that minimizes any adverse impact on the
  9. marine environment, including the seabed and any other natural resources;
  10. after consultation with the Secretary of Energy, that the electricity that will be produced by the facility is needed;
  11. the location of the facility is not within the boundaries of a National Marine Sanctuary or Marine Protected Area;
  12. the applicant will pay the fees required in the application; and
  13. the application was determined by the Secretary under subsection (c) to best serve the public interest.


(a) PRIORITY SITE IDENTIFICATION AND EVALUATION—To accelerate the sensible development of renewable energy facilities in the marine environment, the Secretary shall immediately begin to identify, list, and evaluate those locations within the marine waters under the jurisdiction of the United States seaward of the coastal zone that have the greatest potential, consistent with this Act and section 309(a)(8) of the Coastal Zone Management Act of 1972, as added by section 101 of this Act, for producing energy from renewable energy facilities. In identifying and listing these priority areas the Secretary shall consult with the Secretary of Energy, the Coast Guard, the Administrator of the Environmental Protection Agency, affected coastal states and other public and private institutions and companies with relevant expertise. In evaluating potential sites to be listed, the Secretary shall, to the maximum extent possible, consult with the Office of Energy Efficiency and Renewable Energy and the National Renewable Energy Laboratory of the Department of Energy.

William D. Delahunt


See Also Bays and Estuaries; Coastal Ecosystems; Freshwater and Freshwater Ecosystems; Global Warming; Irrigation; Oceans and Coastlines; Recreational Use and Environmental Destruction; Red Tide; Sea Level Rise; Tides; Tsunami Impacts; Wetlands



Garrison, Tom. Oceanography: An Invitation to Marine Science, 5th ed. Stamford, CT: Thompson/Brooks Cole, 2004.

Web Sites

Great Lakes Information Network. “Coastal Zone in the Great Lakes Region.” November 1, 2006. (accessed February 8, 2008).

Tulane University. “Coastal Zones.” April 9, 2007. (accessed February 8, 2008).

U.S. Environmental Protection Agency. “Coastal Zones and Sea Level Rise.” December 20, 2007. (accessed February 8, 2008).

Juli Berwald

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Coastal Zones

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