The dead zone in the Gulf of Mexico is expected to grow this year to between 7,400 and 8,400 square miles, a size roughly equivalent to the state of New Jersey, according to researchers at the University of Michigan.

That means the zone will be among the top three largest on record; the largest oxygen-starved zone reached 8,484 square miles in 2002.

The dead zones are inadvertently man made: In a sort of reverse circle of life, fertilizer and livestock waste runoff from farms and lawns across the United States overfeeds the Mississippi and other rivers with nitrogen, which prompts massive algae growth in the Gulf of Mexico. The algae sinks and is consumed by bacteria, a process that depletes oxygen supplies along the bottom and lower water levels, choking off aquatic plants and animals. Fish, shellfish and other plants die for lack of oxygen (hypoxia).

The phenomenon has been underway for decades, but has reached its largest proportions in recent years.
“The growth of these dead zones is an ecological time bomb,” said Donald Scavia, a professor at the U-M School of Natural Resources and Environment and director of the U-M Graham Environmental Sustainability Institute. “Without determined local, regional and national efforts to control them, we are putting major fisheries at risk.”

Scavia’s forecasts also include annual dead zone predictions for the Chesapeake Bay, which this year is expected to see a decrease in the size of the dead zone, though it is due to declining runoff resulting from less area precipitation and not pollution reduction.

The Gulf hypoxia research team is supported by the U.S. National Oceanic and Atmospheric Administration’s Center for Sponsored Coastal Ocean Research and includes scientists from Louisiana State University and the Louisiana Universities Marine Consortium.

See an animation of how dead zones are created at National Oceanic and Atmospheric Administration website.

Copyright © 2009 Green Right Now | Distributed by Noofangle Media

In yet another indictment of industrial farming methods and another threat to fish, researchers are reporting vast growth of ocean “dead zones.” Once rare, dead zones are multiplying and now total more than 400 around the world’s coastal waters, putting stresses on marine life by upsetting the underwater food chain, according to an August article in the journal Science.

Worse, these dead areas, created mainly by the dumping of agricultural fertilizers, have grown faster than ever in the last 12 years, increasing by one-third since 1995, according to the study by Professor Robert Diaz of the Virginia Institute of Marine Science.

“Dead zones were once rare. Now they’re commonplace,” Diaz says.

The dead zones form when excess nutrients, mainly fertilizers, cause the overgrowth of algae, which then dies and sinks to the bottom. Bacteria feed on the algae and the decomposition depletes the dissolved oxygen in the waters, leaving them unfit for fish and other marine life.

The largest dead zone in the United States has grown to an enormous 8,500 square miles at the mouth of the Mississippi River. Another dead zone is at the bottom of the main channel of Chesapeake Bay, each summer occupying about 40 percent of its area and up to five percent of its volume, according to researchers.

The situation is causing a decline in fishery production around the world, and can only be improved if farmers can avoid inadvertently adding so much nitrogen-rich fertilizers into runoff waters, say Diaz and collaborating researcher Rutger Rosenberg of the University of Gothenburg in Sweden (who is based near another huge dead zone in the Baltic Sea).

“Scientists and farmers need to continue working together to develop farming methods that minimize the transfer of nutrients from land to sea,” Diaz said, noting that many farmers would be amenable to helping because they could lower their costs for nitrogen fertilizers.

Copyright © 2008 | Distributed by Noofangle Media

While polar bear populations face the challenge of habitat melting beneath their feet, organisms that call water home appear to be grappling with a stranger difficulty: More and more areas of the ocean have oxygen levels too low to sustain them. A report just published in the journal Science asserts that, as tropical oceans warm, regions of low oxygen content are expanding. While researchers make no specific predictions of the ways this will affect individual species, they describe the changes as having potential for wide ecosystem disruptions, with shifts in populations (increased presence of tiny organisms that don’t need much oxygen; fewer predatory fish) affecting animals up and down the food chain.

The scientists analyzed a database of readings taken over the last 50 years, and focused on the most dramatic changes at depths between 300 and 700 meters. According to a statement by team leader Lothar Stramma, of Germany’s Leibniz Institute of Marine Sciences, “whether or not these observed changes in oxygen can be attributed to global warming alone is still unresolved. The reduction in oxygen may also be caused by natural processes on shorter time scales.”

It’s certainly something that has happened cyclically in the past: Stramma points to trends 250 million years ago that caused massive extinctions for Permian-period marine life.

Copyright © 2008 | Distributed by Noofangle Media