articlehighlights

Dead zones, or areas that cannot support life, are increasing along the coast due to:

• agricultural runoff and fertilizers
• industrial waste
• acid rain, which is produced by the burning of fossil fuels

September 2000

Areas in the Gulf of Mexico turn into dead zones at certain times of the year. Source: Gulf of Mexico Foundation.

It’s springtime, and everything seems to be blooming. Unfortunately, this isn’t good news for the Gulf of Mexico, just off the Louisiana and Texas coasts. Each spring, the area turns into a “dead zone.”

What is a “dead zone”?

• Excessive amounts of nitrogen and phosphorus — which make their way to the Gulf from the atmosphere and via rivers polluted with agricultural runoff and municipal and industrial waste — trigger algal blooms.

• The algae use up available oxygen, killing bottom-dwellers such as oysters, clams, and snails, and driving away fish, shrimp, and crabs.

• Excess nitrogen is particularly harmful for marine ecosystems, and can be linked to everything from increased outbreaks of red tides to the deaths of marine mammals and the loss of biodiversity.

And it isn’t just the Gulf area that is affected by an overabundance of nitrogen and phosphorus. All of our coasts are being damaged. Of 139 U.S. coastal areas assessed recently, 44 were identified as severely affected by high levels of these nutrients. What’s more, many scientists predict that the problem will worsen in the coming decades unless action is taken now to reduce nutrient excesses in U.S. waters.

Who or what is responsible?

State and local governments often are responsible for identifying and dealing with nutrient pollution, and their efforts can significantly improve coastal environmental quality. But state and local agencies can’t do it all, and they certainly can’t do it alone. To truly protect our coasts, rivers, and lakes, our nation needs a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways. Nutrient pollution is a complex problem that is taking on ever-larger proportions.

• For example, human activities have more than doubled the amount of nitrogen globally from 1960 to 1990, with the use of synthetic fertilizers accounting for the majority of that growth.

• More than half of all synthetic fertilizers ever produced has been used in the past 15 years.

• In the United States, approximately 20 percent of the nitrogen in these fertilizers seeps into ground water, rivers, and streams, gradually making its way into coastal waters.

• Other sources of nitrogen include animal wastes, waste-water treatment plants, and the combustion of fossil fuels.

• When these fuels burn, nitrogen compounds are released into the atmosphere, and then fall in acid rain, adding significant amounts of nitrogen to some coastal waters.

• Nutrient pollution often crosses local and state boundaries, making it difficult for various government agencies to act cohesively.

• Rivers can carry pollution for long distances. One of the many sources of excess nitrogen in the Gulf, for instance, might be runoff from a farm in Iowa.

• And nitrogen from the atmosphere is a nationwide problem.

How can we address the problem?

Large watersheds that cut across several states need uniform protection. Much needs to be done to help state and local authorities address this problem.

• The federal government should take the lead on issues that span multiple jurisdictions or threaten federally protected natural resources.

• The government also should continue to set clear guidelines for the maximum allowable amounts of nutrients that are released in waterways and address overlaps in existing and proposed federal legislation.

• Developing accurate estimates of nutrients in waterways that lead to the coast is essential for forming effective strategies to curb excesses.

• Federal, state, and local agencies should form partnerships with academic and research institutions to create a national monitoring program.

• And every 10 years, a nationwide assessment should be conducted to determine the extent of nutrient problems and the effectiveness of efforts to combat them.

• But just as importantly, the federal government should be more effective in providing data, information, and technical assistance to state and local coastal authorities.

• A national information clearinghouse that provides assistance on request, or a complete database on the Internet with links to information could go a long way toward helping regional authorities make more informed decisions.

Putting these practices into place, along with strengthening state and local efforts, could realistically reduce the number of severely damaged coastal areas by at least 25 percent in the next 20 years and ensure that no other healthy coastal areas become affected. By developing a systematic, nationwide plan to attack nutrient pollution at its many sources, the government will make huge strides in protecting the many precious natural resources in and around our waterways. It’s time to put an end to coastal “dead zones” and bring marine ecosystems back to life.

© 2000, Robert Howarth. Originally published as an opinion column in HMS Beagle magazine, Issue 80, June 9, 2000 and posted on BioMedNet. Reprinted with permission. See reprint policy.

Bringing Coastal Dead Zones Back to Life

• Check out a list of BioScience articles about sustainability and our future.
• Check out a list of evolution-education-related articles from the pages of BioScience.
• Check out some thematically grouped articles, hand picked by the editors of BioScience, at the AIBS webstore.

BioScience Article

“Dead Zones Spreading in World Oceans.”
In the July 2005, BioScience article, Cheryl Lyn Dybas states, the phrase “dead zone”—coastal waters too low in oxygen to sustain life—is almost synonymous with the Gulf of Mexico. But a similar situation now exists in many other places, says Donald Boesch, president of the University of Maryland Center for Environmental Studies in Cambridge, Maryland. “There’s a dead zone right outside my office window every summer in the Chesapeake Bay,” says Boesch. “Since the 1970s, this lifeless zone has become a yearly phenomenon, sometimes affecting 40% or more of the bay.” Read the citation, or log in to purchase the full article.
http://caliber.ucpress.net/doi/abs/10.1641/0006-3568%282005%29055%5B0552%3ADZSIWO%5D2.0.CO%3B2

Dead zone woes

A short news article on how dead zones affect coastal economy and fisheries.
http://www.lubbockonline.com/news/092997/deadzone.htm

Gulf of Mexico Hypoxia Assessment

Read the full report by the National Centers for Coastal Ocean Science (1999). Other links will take you to more information about hypoxia in the Gulf of Mexico.
http://www.nos.noaa.gov/products/pubs_hypox.html

The Aquatic Net

This site has news and science information on oceans and fisheries.
http://www.aquanet.com/

Scorecard: your community’s pollution

“Enter your [U.S.] zip code and find out what pollutants are being released into your community — and who is responsible.” Part of the Environmental Defense Network, the second link below.
http://www.scorecard.org/
http://www.environmentaldefense.org/home.cfm

Read a book

Song for the Blue Ocean: Encounters Along the World’s Coasts and Beneath the Seas. Marine scientist Carl Safina encourages readers to take a wider interest in the oceans, especially because so much of that great blue expanse is now threatened by human progress. Henry Holt & Company, Inc., Jan. 1999.

Protect the oceans and marine life

The Ocean Conservancy offers a variety of advocacy campaigns, listed right on their home page, for your participation.
http://www.oceanconservancy.org/

Reef Relief

“A nonprofit membership organization dedicated to preserving and protecting living coral reef ecosystems through local, regional and global efforts.” Includes tips for boaters and divers.
http://www.reefrelief.org/main.html

The Surfrider Foundation

“A non-profit environmental organization dedicated to the protection and enjoyment of the world’s oceans, waves and beaches, for all people, through conservation, activism, research and education.” The second link takes you to their current campaigns.
http://surfrider.org/
http://www.surfrider.org/campaigns

How to reduce water pollution

There are many ways to directly and indirectly protect your area’s waters, using these tips when “in your household, in your backyard, on the road, or on the water.”
http://www.chesapeakebay.net/info/helpbay.cfm

Helping coral reefs

The Nature Conservancy offers tips on how to help protect coral reefs.
http://nature.org/magazine/fall2002/coralreefs/explore/