Florida agriculture could have caused the dead water discovered by fishermen in January. Nitrogen-rich waters may have flowed from the Shark River after a recent period of above-average rainfall. South Florida had extremely heavy rain by early December, almost two and half times normal.
Larry Brand, a marine biology professor at the University of Miami, says, ?The nitrogen is coming off the sugar cane fields.? Farmers don?t put the chemical directly on their crops; instead, it would have come from the peat on which they grow the sugarcane.
Barbara Miedema, spokeswoman for Sugar Cane Growers Cooperative of Florida, says growers have worked to control nutrient releases and have substantially cut back on the amount of phosphorus that ends up in the waters off South Florida.
Researchers looking at the satellite data also note that the black water seems to have a offshore source as well. Fresh water from the area reaches the bay through what some divers call the Shark River hole. Diver Chris Sizemore of Bonita Springs says a natural spring is near the center of the black water. ?It is active and pours out a lot of water,? he says.
Scientists are meeting in St. Petersburg to try to determine the causes of the dead zone of black water. No fish can be found there, but there are no dead fish either. Instead, it looks as if all marine life has fled the area.
Fishermen were the first to spot the black water. They said it had large gelatinous globs floating in it and spider web-like filaments running through it. They also noted an absence of game fish in the normally rich fishing waters, and they are reporting the worst season for fish in many years.
Satellite imagery from January and February shows that the black water mass began as early as November. Dr. Frank Muller-Karger and Dr. Chuanmin Hu say satellite pictures don?t tell the whole story, but they might give clues about the source of the water.
Other scientists with the Florida Marine Research Institute in St. Petersburg and the Mote Marine Laboratory in Sarasota are testing samples of the water to see if the chemicals, dissolved matter and organisms in it might point to a source.
Erich Mueller, director of the Center for Tropical Research in the Keys, says, ?[River runoff] sounds right now like the most logical explanation, but it?s certainly not a done deal.?
To learn more,click here. A zone of dying sponges and coral off Key West has suddenly changed the the black water dead zone mystery to a major environmental concern.
In the first reliable underwater assessment of the dead zone?s impact on marine life, a commercial diver has documented that there is enough damage to raise fears that the baffling blob may have left an area of unseen destruction in its wake as it?s slowly drifted from the Gulf of Mexico across Florida Bay over the last few months. ?This certainly sounds like it?s the effects of something very nasty going on,? says Billy Causey, superintendent of the Florida Keys National Marine Sanctuary.
The devastated sponges were observed over the weekend in the northwest channel off Key West by Ken Nedimyer, a member of the sanctuary?s advisory council who collects specimens for the aquarium trade. ?The water was a creepy green at the surface and by the time I got to the bottom, it was really creepy and dark,? he says. He noted that six species of rope sponge were the hardest hit, with 50 to 75 percent wiped out, as well as a number of other sponges dead or dying. Brain coral and starfish also seemed to be suffering. Fish in the area seemed healthy, though curiously unhungry.
?There?s a real meltdown occurring down there right now,? Nedimyer says. Before his report, scientists had not confirmed any toxic effects from the black water but Nedimyer?s observations are serious enough to cause the sanctuary to make plans to send its own divers to survey for more widespread damage.
While the mass described as the color of sewer water is now breaking up and shrinking, at one point it spanned several hundred miles. Scientists are still sorting through water samples, satellite images, weather reports and historical studies and observations. The sponge dieoff is a strong indication that the cause of the dead zone was an explosion of some sort of microscopic plankton, says Brian Keller, the sanctuary?s science coordinator.
During a series of algae blooms that plagued Florida Bay in the mid-1990s, sponges, which feed by filtering water, were among the first organisms to go, in vast acres, followed by seagrass beds. Those blooms did not kill fish, like red tide does, but fish avoid the areas during outbreaks and lose forage and shelter until the areas recover, which can take years.
?It?s a phenomenon about which we are uncertain,? says Beverly Roberts, research administrator at the Florida Marine Research Institute in St. Petersburg. She believes it could be caused by anything from pollution to some sort of decaying plant material, perhaps washed into the sea from the land.
Water samples studied so far have shown medium to high levels of two types of phytoplanktons, tiny plants so essential to the marine food chain that they?re called ?the grass of the sea,? Roberts says. ?It?s eaten by a lot of smaller stages of the fishes. They?re normal in sea water but plankton or a variety of them can cause problems in high concentrations.?
Keller says, ?The fact that it appears to be a fairly selective mortality indicates to me that it?s not like some general toxin in the water column that would kill everything.?
See news story, ?Dead Zone Discovered in Ocean?, click here.
To find how ocean current will effect our future, read ?The Coming Global Superstorm? by Whitley Strieber and Art Bell, now only $9.95 for an autographed hardcover, click here.
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