Fwd: [graffis-l] THE DEAD ZONE' GULF OF MEXICO

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>Experts worry about lack of progress in efforts to reduce lifeless z

>Posted by: " Mark Graffis " mgraffis mgraffis

>Mon Dec 31, 2007 5:46 pm (PST)

>http://sciencenews.org/articles/20071222/bob10.asp

>

>Science News Online

>Week of Dec. 22, 2007; Vol. 172, No. 25/26

>

>Dead Serious

>Experts worry about lack of progress in efforts to reduce lifeless zone in

>the Gulf of Mexico

>Sarah C. Williams

>

>The water that tumbles out of the Mississippi River into the salty Gulf of

>Mexico has traveled thousands of miles. From its source in Minnesota, the

>river winds through 10 states on its journey to the ocean, collecting

>runoff from the Rocky Mountains, the Appalachian Mountains, and everywhere

>in between. The river flows through the fields of the Corn Belt, gathering

>fertilizer, and through cities, where sewage leaches into its currents.

>

>MURKY WATERS. The latest map of the dead zone, created in summer 2007,

>shows the span of lifeless waters off the coast of Louisiana. Red and

>yellow highlight areas where oxygen levels are too low for fish and shrimp

>to survive.

>Nancy Rabalais, Louisiana Universities Marine Consortium

>

>By the time the Mississippi empties into the Gulf, along the shores of

>Louisiana, it carries more than just water. Nutrients from both

>agricultural and urban runoff convert the river's outflow into a rich

>broth. Every summer in the Gulf, this enriched water encourages algae to

>grow in massive quantities, using up the oxygen that fish and other marine

>species need to survive. The result of this process: an area the size of

>Massachusetts that supports almost no life beyond algae and bacteria.

>

>This 7,900-square-mile seasonal dead zone has been around since the 1970s,

>when scientists first began taking notice of the fish-depleted area. Now

>the Gulf of Mexico dead zone is the largest such zone in the United States

>and one of the largest in the world. In the summer of 2007, the dead zone

>covered the third-largest area since scientists started measuring it in

>the 1980s. But the problem was largely ignored until the '90s when 17

>environmental groups threatened to sue the U.S. Environmental Protection

>Agency for not taking action on the problem. In response, the National

>Science and Technology Council published an assessment of the dead zone in

>2000. The report outlined the problem and the steps lawmakers should take

>to reduce the size of the area. But the draft of a new action plan,

>released by the council in November, suggests that little progress has

>actually been made in the past 7 years.

>

>Now the years of inaction are exacting a toll, scientists say. New

>research hints that a nutrient that had been largely ignored in the dead

>zone may, in fact, be driving the problem past the point of no return.

>What's more, much of the runoff that causes the dead zone comes from

>cornfields. And an increasing demand for corn, used to make ethanol, could

>mean more runoff, and a worsening of the habitat destruction in the Gulf.

>

>Don Boesch, now president of the University of Maryland Center for

>Environmental Science in Cambridge, was among the first scientists to take

>notice of the dead zone. After hearing anecdotal accounts of poor fishing

>in once-thriving sections of the Gulf, he decided to map these areas in

>the late 1970s.

>

> " Contrary to what was thought at the time—that this dead zone area would

>be very patchy, would come and go—we found it was massive in size and

>pretty persistent over most of the summer, " he says.

>

>This means that every summer, numerous species' habitats disappear. It's

>been hard to quantify the effect on commercial fishing, though, says David

>Whitall of the National Oceanic and Atmospheric Administration in Silver

>Spring, Md.

>

>Whitall recently studied the impact of the dead zone on brown shrimp, the

>primary catch in the Gulf. In the April 2007 Marine Pollution Bulletin, he

>and his colleagues showed that shrimpers catch fewer brown shrimp during

>years when the dead zone is largest.

>

> " It's not so much a problem of shrimp dying as of shrimp moving " out of

>once-productive areas, he says.

>

>But any decline in shrimp numbers can't be pinned entirely on the dead

>zone, Whitall says, because there are so many factors influencing marine

>populations. Overfishing and climate changes affect the shrimp populations

>as well.

>

>In addition, relying on records from shrimpers to estimate whether shrimp

>are on the decline is inherently biased—any shrimper will quickly learn to

>avoid dead-zone areas, where he doesn't catch anything. And some

>scientists suggest that the " herding effect " of the dead zone may in fact

>help shrimpers.

>

> " There are some areas, like the edges of the dead zone, where you might

>actually have a larger catch because of that herding effect, " notes Boesch.

>

>Though it's hard to find quantitative evidence that shows the destruction

>caused by the dead zone, most experts agree that such an area isn't good

>for the long-term health of the oceans. So scientists are focusing their

>efforts on figuring out how to bring the dead zone back to life.

>

>That focus, over the past decade, was largely on monitoring and minimizing

>the nitrogen that runs into the Mississippi from fertilizer. Spread on

>fields, synthetic nitrogen fertilizers spur crop growth. But when they

>wash off the fields into water, fertilizers help algae bloom.

>

>The 2000 report identified fertilizer, and specifically nitrogen, as the

>primary cause of the Gulf dead zone. But there's another nutrient that

>algae require: phosphorus. Only within the past few years, scientists say,

>has it become clear that phosphorus should be included in efforts to

>reduce nutrient runoff into the Mississippi.

>

>Don Scavia of the University of Michigan in Ann Arbor recently created a

>model to study the interplay between phosphorus and nitrogen in the dead

>zone. His simulation, published Dec. 1 in Environmental Science &

>Technology, showed that a dead zone can switch from being limited in size

>by how much nitrogen flows into it to being limited by its phosphorus

>content. He hypothesizes that such a switch is happening right now in the

>Gulf.

>

> " Over the past 30 to 40 years, " he says, " we've added so much nitrogen to

>the system that there's plenty of it around, and phosphorus is becoming

>limiting. "

>

>This doesn't mean that all efforts to monitor and control the dead zone

>should switch to phosphorus, he says, but that policy makers need to take

>both nitrogen and phosphorus into account. In many cases, the steps to

>control the nutrients are the same. About 75 percent of nitrogen and

>around 60 percent of phosphorus in the runoff comes from fertilizer, with

>the rest leaking into the rivers from urban sources.

>

>Scavia says that controlling phosphorus alone probably would not alleviate

>the dead zone, and might even make it worse. Reducing phosphorus, he says,

>would clear up algal blooms close to the shore. This would allow

>nitrogen-laden water to flow farther out into the Gulf, where phosphorus

>exists naturally. Here, the vastness of the Gulf and the mixture of

>nitrogen and phosphorus would allow for an even larger dead zone than the

>coastal area permits.

>

> " This has actually happened in the Neuse River in North Carolina and in

>the Pearl River in Hong Kong, where they controlled phosphorus and it made

>the problem move downstream and become worse, " says Scavia.

>

>While controlling only phosphorus would worsen the problem, controlling

>only nitrogen would be equally detrimental to the dead zone. Phosphorus,

>it turns out, is harder to get rid of than nitrogen once it's in the ocean.

>

>When algae and other phytoplankton die, their phosphorus- and

>nitrogen-rich corpses sink to the bottom of the ocean. Much of the

>nitrogen is removed from the water by microbes that convert nitrogen

>compounds, like nitrate and nitrite, into nitrogen gas which makes its way

>up through the water and into the atmosphere. Phosphorus, however,

>accumulates in the sediments and water column, feeding future algae growth.

>

>This means that high levels of phosphorus can lead to problems that remain

>long after phosphorus and nitrogen runoff is controlled. This struggle is

>playing out in the Baltic Sea right now, in an out-of-control dead zone.

>

> " You've gotten into a vicious cycle, " Boesch says. " The system there is so

>overloaded with phosphorus that there are tens of years of phosphorus

>available. "

>

>In addition to now being fingered for limiting the dead zone in the Gulf

>of Mexico, phosphorus has long been described as the limiting factor in

>freshwater systems, such as the Mississippi River itself. In rivers,

>cyanobacteria that get energy through photosynthesis, like plants, thrive.

>These bacteria process nitrogen from the atmosphere into the kind of

>nitrogen that feeds algal growth. Limiting phosphorus in these situations

>will improve not only the dead zone but the health of the Mississippi and

>the rivers that empty into it.

>

>Most researchers agree that reducing both nitrogen and phosphorus is what

>needs to happen to shrink the dead zone.

>

> " A lot of the management steps you would take to go after nitrogen would

>help with phosphorus too, " points out Robert Howarth of Cornell

>University. " It's not like it's twice as much work to go after both. "

>

>These management steps include limiting fertilizer use on fields and

>requiring buffer zones and wetlands between agricultural fields and

>rivers, to catch nutrients. These steps have been suggested before, in the

>2000 dead-zone assessment, but policy makers have not yet provided the

>money needed to put them into practice.

>

>In a recent book, Scavia and colleagues reported on recently surveyed Iowa

>farmers who were asked whether they'd be willing to implement such changes.

>

> " They would be happy, in fact they would prefer, to have a more diverse

>landscape with wetlands and conservation buffers, " he says. " They would do

>that if the government would pay them to do that rather than pay them to

>grow corn. As long as money is coming through. "

>

>But right now, the most money comes from growing corn. Scientists worry

>that a recent increase in corn production to support the ethanol industry

>will soon be reflected in the size of the dead zone.

>

>Corn, says Scavia, is grown in soil with tile drains. More nitrogen seeps

>into the river from cornfields than from fields growing other crops.

>

> " Corn is really the leaky crop that causes most of the nitrogen problems

>in the Gulf, " Scavia says. And this year, farmers grew 14 million more

>acres of corn than ever before. A report on the impact of biofuel

>production on U.S. water quality issued by the National Research Council

>raises concerns that this increase will lead to more nitrogen flowing down

>the Mississippi as well as to numerous other water-quality problems.

>

>In an upcoming paper, Howarth and colleagues estimate that the conversion

>of soybean fields to cornfields to support the biofuel industry will mean

>an extra 117 million kilograms of nitrogen entering rivers across the

>country. Many of these rivers flow into the Mississippi. This 37 percent

>increase in nitrogen runoff, scientists hypothesize, will lead to an

>increase in the size of the Gulf's dead zone.

>

>Howarth says action to reduce nitrogen and phosphorus pollution must be

>taken now, before the dead zone gets out of control.

>

> " It may be, " he says, " that once we have the political will to reduce the

>nutrients in the Gulf of Mexico, it will be harder to backtrack than it

>would have been to stop the nutrient flow in the first place. "

>

>With this urgency in mind, environmental lobbyists are pushing—so far, in

>vain—to get conservation measures into the next farm bill, the U.S.

>legislation that governs agricultural policy and is rewritten every few

>years. The next version of the bill, environmental groups hope, could set

>new guidelines for fertilizer use and allocate money to farmers who set

>aside land for wetlands and river buffer zones.

>

>Boesch, who has followed the dead-zone research for decades, echoes the

>message of urgency, and says the new draft action plan is disappointingly

>timid.

>

> " They're kind of backsliding on it rather than being more aggressive about

>it, " he says. " I think we're not yet serious about making the commitments

>to deal with the problem. "

>

>-------------------------

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>References:

>

>Committee on Environment and Natural Resources. 2000. An Integrated

>Assessment: Hypoxia in the Northern Gulf of Mexico. Washington, D.C.:

>National Science and Technology Council.

>

>Committee on Water Implications of Biofuels Production in the United

>States, National Research Council. 2007. Water Implications of Biofuels

>Production in the United States. Washington, D.C.: National Academies

>Press. Available at http://books.nap.edu/catalog.php?record_id=12039.

>

>Environmental Protection Agency. 2007. Gulf Hypoxia Action Plan 2008.

>Available at http://www.epa.gov/msbasin/taskforce/pdf/2008draft_actionplan.pdf.

>

>O'Connor, T., and D. Whitall. 2007. Linking hypoxia to shrimp catch in the

>northern Gulf of Mexico. Marine Pollution Bulletin 54(April):460-463.

>Abstract available at http://dx.doi.org/10.1016/j.marpolbul.2007.01.017.

>

>Scavia, D., and K.A. Donnelly. 2007. Reassessing hypoxia forecasts for the

>Gulf of Mexico. Environmental Science & Technology 41(Dec. 1):8111­8117.

>Abstract available at http://dx.doi.org/10.1021/es0714235.

>

>Further Readings:

>

>Rabalais, N.N., R.E. Turner, and D. Scavia. 2002. Beyond science into

>policy: Gulf of Mexico hypoxia and the Mississippi River. BioScience

>52(February):129-.

>

>Rabalais, N.N., R.E. Turner, and W.J. Wiseman Jr. 2002. Gulf of Mexico

>hypoxia A.K.A. " The Dead Zone. " Annual Review of Ecology Evolution and

>Systematics 33(August):235-263.

>

>Raloff, J. 2004. Limiting dead zones. Science News 165(June 12):378-380.

>Available at http://www.sciencenews.org/articles/20040612/bob9.asp.

>

>______. 2004. Dead waters. Science News 165(June 5):360-362. Available at

>http://www.sciencenews.org/articles/20040605/bob9.asp.

>

>Scavia, D., N.N. Rabalais, et. al. 2003. Predicting the response of Gulf

>of Mexico hypoxia to variations in Mississippi River nitrogen load.

>Limnology and Oceanography 48(May):951-956.

>

>Sources:

>

>Donald F. Boesch

>University of Maryland, Cambridge

>Center for Environmental Science

>P.O. Box 775

>Cambridge, MD 21613

>

>Robert W. Howarth

>Department of Ecology and Evolutionary Biology

>Cornell University

>E311 Corson Hall

>Ithaca, NY 14853

>

>Nancy Rabalais

>Louisiana Universities Marine Consortium

>Defelice Center

>8124 Highway 56

>Chauvin, LA 70344

>

>Don Scavia

>University of Michigan, Ann Arbor

>School of Natural Resources and Environment

>Dana Building, 440 Church Street

>Ann Arbor, MI 48109-1041

>

>David Whitall

>National Centers for Coastal Ocean Science

>National Ocean Service

>National Oceanic and Atmospheric Administration

>N/SCI 1, SSMC 4

>1305 East West Highway

>Silver Spring, MD 20910

>

>http://www.sciencenews.org/articles/20071222/bob10.asp

>

> From Science News, Vol. 172, No. 25/26, Dec. 22, 2007, p. 395.

 

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