Photo credit: The Institute for Marine Remote Sensing (IMaRS at USF).

WHERE’S THE OIL NOW? A month after the Deepwater Horizon drilling platform explosion, a heavy blanket of crude oil has hit the Louisiana wetlands, and the National Oceanic and Atmospheric Administration confirms that a small portion of the slick has reached the Loop Current that slings water around Florida and into the Atlantic, further increasing the possibility that the disaster won’t be confined to the Gulf of Mexico.

WHERE’S IT GOING? Dr. Hu Chuanmin, executive director of the Institute for Marine Remote Sensing (IMaRS) at the University of South Florida, is convinced that the Florida Keys are now in danger. Hu is an expert in optical oceanography — using light from remote imaging sources (such as satellites) to understand what is going on in the ocean. “It may be one week, or two or even more, but there is no doubt that (oil) will reach the Florida Keys,” Hu said in an interview.

In the image above, generated from satellite data on Tuesday, it’s easy to track the Gulf Loop Current as it flows into the Florida Straits, the body of water between Florida and Cuba. Water in the current flows at speeds approaching 100 miles a day, and it produces eddies that spin off and move in a counter-clockwise motion. “By tracking flood waters from the Mississippi River, we know that whatever flows from there comes through the Florida Straits and will impact the Keys,” Hu says.

Hu wrote a journal article about this pattern, tracking flood waters as they flowed from the Mississippi delta in July 2004. By August 4, 2004, a dark plume 6 to 15 miles wide was clearly visible (image right) flowing through the Florida Straits and over portions of the barrier reef tract.

WHAT’S AT RISK? If oil reaches the Florida Keys, it could cause major damage to the only coral reefs off the coast of the continental United States. Reefs are a vital part of the marine ecosystem, providing shelter, food and breeding sites for many plants and animals and providing natural storm protection for the coast. The reefs are also important to southeast Florida’s economy, according to the state’s Department of Environmental Protection, bringing in millions of dollars annually from recreational and commercial fishing.

Even before hitting the Keys, the millions of gallons of oil that have already leaked from the seafloor will have a profound effect on life in the Gulf of Mexico for “years, potentially decades,” said Rowan Gould, the acting director of the U.S. Fish and Wildlife Service, at a press conference on Tuesday.

The potential threat to Bluefin tuna is a particularly stark example of the dangers to marine life. Bluefin populations are already devastated by overfishing, and the oil currently spilling into the Gulf poses a direct threat to the tuna larvae currently hatching in their spawning grounds, which are near the oil’s source.

If oil enters the Florida Straits, no one knows for sure how much damage it will do in the Keys or on Cuba’s northern coastline, which is also likely to be hit. The longer that the oil floats, the more likely it is that volatile substances in it will evaporate — a positive side effect of getting caught in the eddies. Of course, that merely puts the compounds into the air, where they can also do damage.

If the oil flows over the coral reef, the damage will depend in large part on whether it stays at the surface. “Under no circumstances should dispersants be used on an oil slick in the vicinity of a coral reef,” says Eugene Shinn, who recently retired from the U.S. Geologic Service, where he specialized in reef ecology. Dispersants would cause oil droplets to sink, he says, which could prove fatal to the tiny coral polyps. 
 

Special thanks to Osha Davidson