Dead in the Water

Years before the Deepwater Horizon disaster, before the underwater volcano of oil threatened to create a dead zone in the Gulf of Mexico, scientists recognized another dead zone in the Gulf. The New Orleans Times-Picayune won a Pulitzer in 1997 for documenting the devastation around the mouth of the Mississippi River. The 7,000-square-mile dead zone was caused by algae blooms, feeding on agricultural and sewer runoff, that deplete the oxygen in the water. Combine the existing problem with the still-leaking oil well, and you’ve got a recipe for a completely destroyed ecosystem.

The following is a summary (by Mark Schleifstein) of a Pulitzer-prize willing paper about the Dead Zone in the Gulf of Mexico, from 1996. It’s important to not that much of the problem here is coming from agriculture – fertilizer, pesticides, and CAFO runoff are literally killing the ocean. My husband can give you much more detailed information about soil fertility and the causes of runoff, but the basic fact is that the blanket applications of fertilizers, pesticieds, herbicides, antibiotics, steroids, etc. used in modern agriculture are ineffective, and mostly end up in the streams and aquifers near the farms. This water, in turn, reaches the Gulf of Mexico – killing it.


Is it possible to kill 7,000 square miles of the Gulf of Mexico? Alarmed scientists are beginning to think it is more than a possibility; it’s increasingly likely. Already, the dead zone, a seasonal area rendered almost lifeless byvast amounts of pollution pumped into the Gulf of Mexico from the Mississippi River, is expanding. Without action, it may become permanent.

Fertilizer, sewage brew dead zone

Biologist Nancy Rabalais fights nausea as she struggles into a wet suit and scuba gear on the pitching deck of the R.V. Acadiana about 15 miles off the Louisiana coast.

She is preparing to descend along the metal leg of an abandoned oil rig to the shallow bottom of the Gulf of Mexico, where she will replace a meter that measures the amount of oxygen in the water.

It’s not the most pleasant of chores for a marine biologist prone to seasickness. But Rabalais considers a little nausea a small price to pay to gain another clue to the Gulf of Mexico’s biggest, most alarming mystery:

How do we stop the dead zone?

A 7,000-square-mile swath of Gulf water stretching from the mouth of the Mississippi River to the Texas border, the zone becomes so devoid of oxygen each summer that it kills the clams, crabs, worms and other organisms that live on and in the sediment, destroying the food chain from the bottom up.

A death sentence for the region’s rich fish stocks if it becomes permanent, the zone already is changing the face of fishing in the Gulf.

Every year, fishing boats are forced to go farther and farther out, sometimes hundreds of miles from port, to find viable fishing grounds beyond the zone — using precious time and fuel that can mean the difference between profit and loss.

The dead zone also is encroaching on areas usually rich in menhaden, the small fish used for fish meal, which is used to feed farm-raised fish. Commercial menhaden fishers suspect it is reducing the Gulf catch — worth $91 million in 1994 — by killing young fish emerging from the marshes and forcing others into distant areas of the Gulf, far from their nets.

The sheer size of the zone traps fish, forcing them to flee or starve.

“We know where oxygen is low that fish and shrimp and the food they eat disappear or die,” said Gene Turner, interim director of the Coastal Ecology Institute at Louisiana State University. “We can’t yet say they don’t go somewhere else and get caught, but we’re talking about 7,000 square miles.”

It begins in the spring, when the Mississippi River is swollen by rains and melted snow that wash a rich mixture of agricultural fertilizers and municipal sewage from 40 states downstream into the Gulf.

The lighter fresh water floats on top of the denser salt water of the Gulf, creating layers. As spring turns to summer, the sun combines with the pollution from fertilizers and sewage to fuel huge blooms of algae.

The chemicals in the pollution are mostly nitrogen and phosphorous, and they are known as nutrients, because they make things grow. When it’s corn in Iowa or wheat in Kansas, nutrients are good. But when it’s too much algae in the ocean, nutrients can be deadly.

When the algae dies, it sinks to the bottom, where its decay uses up oxygen in the saltier water. Oxygen from the surface can’t get past the freshwater layer at the top to replenish the water below. By midsummer, all the oxygen in a vast area of the Gulf may be gone.

“The effect can be akin to taking Saran Wrap and placing it over (an area the size of) Connecticut and Rhode Island, slowly pulling it down and suffocating everything beneath it,” said Melissa Samet, a lawyer and wildlife biologist with the Sierra Club Legal Defense Fund.

Mystery zone

Rabalais and other scientists want to learn the exact sources of the nutrients causing the algae blooms, determine the long-term effects of the low oxygen conditions — called hypoxia — on fish, and discover how to reduce the nutrients that reach the Gulf.

It’s already clear from the work of Rabalais and others that the dead zone’s expansion mirrors an increase in the use of chemical fertilizers by farmers in the Midwest and in manure runoff from livestock operations. Sewage from the heavy urbanization of land along the Mississippi and its tributaries is only a fraction of the problem, say officials of the U.S. Geological Survey.

Nitrogen, and to a lesser extent phosphorus, are thought to be the driving force behind the algae blooms. Both are used as fertilizers on millions of acres of farmland in the 30 states within the vast Mississippi River watershed. The chemicals also are found in animal and human wastes that are washed by rainfall into the river and its tributaries.

But scientists concede that much about the dead zone and its dynamics remains a mystery:

– Why, for instance, was the 1995 dead zone so large two years after a major flood of the Midwest, when the amount of water carried by the river was back to normal?

– Are the nutrients trapped in the sediment on the bottom of the Gulf of Mexico along Louisiana’s coast becoming remixed along the Gulf Coast in some unknown fashion years after major floods?

– And how will the repeated killing of bottom-dwelling organisms dependent on oxygen, and their replacement with sulfur-laced networks of non-oxygen-breathing bacteria, affect this most fertile area of the Gulf?

The answers found in dead zones in other parts of the world are not comforting.

Driven by the rapid pace of population growth and economic development, dead zones are a new and largely unstudied problem that is growing more quickly than governments and scientists can keep up with it.

Scientists say that in just the past few years, as many as a dozen dead zones have appeared in different areas of the world, all caused by the same combination of agricultural fertilizer and sewage runoff.

“No other parameter of such ecological importance has been changed so drastically in such a short period of time by human activities as dissolved oxygen contents in the world’s oceans,” said Robert J. Diaz, a researcher at the Virginia Institute of Marine Sciences and president of the Atlantic Estuarine Research Society.

Five of those zones have so little oxygen that they are on the verge of collapse. “It won’t take very much more to push them over the edge,” Diaz said.
One of the five is the area off the Louisiana coast.

The dead zone in the Gulf of Mexico waxes and wanes each year, but if it follows the pattern in similar areas, it could become permanent, bereft of oxygen-breathing life, including the valuable fish and shrimp along the coast.

Dead zones start as an infrequent occurrence, showing up every two or three years. Organisms on the sea floor are suffocated, but soon replaced when the zone breaks up.

Then the events become seasonal, as they have in the Gulf, and the ecology of the affected ocean becomes stressed over long periods of time, harming fish and driving fishing boats elsewhere.

Finally, the dead zone becomes permanent and a major change takes place: Fish, shellfish and crustaceans that need oxygen are replaced by forms of bacteria that thrive in a no-oxygen world.

The four other dead zones on the verge of collapse — all sandwiched between the highly developed Nordic nations and Germany — are seasonal.

“All you have to do in these systems is increase the exposure time at these concentrations (of low oxygen), or have a further decline of oxygen levels, and we are predicting permanent changes in the benthic (bottom-dwelling organisms) communities and the temporary or permanent collapse of fisheries stocks,” Diaz said.

Sometimes, perversely, a dead zone can temporarily produce more fish, slowing efforts to fix the problem.
In the 80-mile-wide Kattegat Channel between Denmark and Sweden, annual bouts of low oxygen began in 1980. By 1984, fishers were catching record amounts at the same time low oxygen levels were being recorded, Diaz said.

The catch, however, was the Norway lobster, which normally burrows into the ocean floor.

What was happening, Diaz said, was that the lobsters were trying to swim higher in the water to find oxygen, and were more vulnerable to being scooped up by trawls. In the Gulf of Mexico, biologist Don Harper of Texas A&M University’s marine laboratory has observed a similar behavior pattern in worms that burrow beneath the ocean floor, but in hypoxic waters climb over each other to form balls in search of oxygen.

In 1988, 3,000 square kilometers of the Kattegat Channel’s bottom was affected by hypoxia. Fisheries collapsed and bottom-living organisms were killed.

“The Norwegian lobster fishery still has not recovered,” Diaz said.

We’re way behind

The growth of the Gulf of Mexico’s dead zone has far outpaced efforts to pin down its specific causes and behavior, let alone come up with a policy to solve the problem. Like many other ecological problems related to fish habitats, it was discovered years ago, but its significance wasn’t realized until money was made available to study it.

And today, the responsibility for fixing it is mired in a complex mishmash of overlapping agencies and jurisdictions, a problem that afflicts much of fisheries management.

Although the National Marine Fisheries Service has the authority to deal with issues affecting ocean fisheries, including pollutants coming from inland sources, the farm runoff problems also fall under the auspices of the Environmental Protection Agency, the Department of Agriculture and the Fish & Wildlife Service, as well as a variety of state agencies. The U.S. Geological Survey already is involved in a separate investigation of fertilizer runoff problems — the contamination by nitrogen of ground water that is used for drinking water across the Midwest.

Answers available

The solutions, in theory, are simple. But they may be politically impossible. Basically, they require changes in land use throughout the Midwest:

* Creating a buffer of grass between fields and streams that will filter much of the nutrients before they reach the water.
* Using farming methods that rely less on chemical fertilizers and pesticides, either through no-till farming or with new satellite-based computerized crop systems that measure the need for fertilizer more accurately.
* Building wetlands at strategic locations along the paths of agricultural runoff ditches to capture and treat the fertilizer runoff.
* Creating similar wetlands to treat sewage-tainted water washing from suburbs and cities.
* Improving enforcement of sanitary codes to force the replacement of inadequate septic tanks and sewage systems in urban and suburban areas.
* Forcing replacement of inadequate sewage-treatment ponds and drainage fields at pig, chicken, cattle and dairy farms.

The problem is persuading farmers and city-dwellers alike to shoulder the cost of such improvements for the benefit of people hundreds or thousands of miles away, and then finding money to pay for the improvements. That would be a massive undertaking requiring unprecedented cooperation between local, state and federal governments, and perhaps billions of dollars.

Those trying to solve the dead zone problem are going to have to deal with hard political realities, said Clyde Walker of the Natural Resources Conservation Service.

“The Environmental Protection Agency is faced with dramatic cuts to its budget and an apparently unsympathetic Congress,” he said.

And John Burt, special assistant to the chief of the federal Natural Resources Conservation Service, said that with the world’s grain supply low and prices for wheat, cotton and corn high, for the first time in a number of years there is pressure on farmers to increase production, which could mean they will increase their use of fertilizers.

Burt also complained that environmental groups have hurt the chances of finding the political clout to reduce agricultural runoff by focusing so much of their criticism on farmers, without targeting poor pollution practices of city sewage-treatment plants and residents who use too much fertilizer on their lawns and backyard gardens.

“When the floods of 1993 covered the Midwest, it wasn’t just agricultural land that was flooded, but sewage-treatment plants and urban streets,” Burt said. “All these loads made their way down to the Gulf,” he said.

© 1996, Times-Picayune ”


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