The Gulf of Mexico oil spill is expected to strike the Louisiana coastline today, and officials are bracing for impacts to shorebirds, turtles, shellfish and other endangered wildlife. But many ocean scientists are now raising concerns that a powerful current could spread the still-bubbling slick from the Florida Keys all the way to Cape Hatteras off North Carolina.

These oceanographers are carefully watching the Gulf Loop Current, a clockwise swirl of warm water that sets up in the Gulf of Mexico each spring and summer. If the spill meets the loop — the disaster becomes a runaway.

“It could make it from Louisiana all the way to Miami in a week, maybe less.” said Eric Chassignet, director of the Center for Ocean Atmospheric Prediction Studies at Florida State University. “It is pretty fast.”

Right now, some computer models show the spill 30 to 50 miles north of the loop current. If the onshore winds turn around and push the oil further south: “That would be a nightmare,” said Yonggang Liu, research associate at the University of South Florida who models the current. “Hopefully we are lucky, but who knows. The winds are changing and difficult to predict.”

Imagine the loop current as an ocean-going highway, transporting tiny plankton, fish and other marine life along a watery conveyor belt. Sometimes it even picks up a slug of freshwater from the Mississippi River — sending it on a wandering journey up to North Carolina.

The Gulf Loop Current acts like jet of warm water that squirts in from the Caribbean basin and sloshes around the Gulf of Mexico before being squeezed out the Florida Strait, where it joins the larger and more powerful Gulf Stream current.

Fishermen follow the current as a harbinger of good catches. It has also transported algal blooms — toxic “red tides” — from the Gulf of Mexico to beaches and bays along the southeast Atlantic coast.

Oceanographer George Maul worries that the current could push the oil slick right through the Florida Keys and its 6,000 coral reefs.

“I looked at some recent satellite imagery and it looks like some of the oil may be shifted to the south,” said Maul, a professor at Florida Institute of Technology in Melbourne, Fla. “If it gets entrained in the loop, it could spread throughout much of the Atlantic.”

In fact, new animation from a consortium of Florida institutions and the National Oceanic and Atmospheric Administration, predicts a slight southward shift in the oil over the next few days.

Emergency responders are working to cap the oil spill at its undersea source, but admit it could be weeks before the well is shut down.

Scientists at the National Oceanic and Atmospheric Administration are expected to release their predictions of the spill and the loop current early this week. A spokeswoman for the agency did not respond to requests for comment by Discovery News.

-Eric Niiler is a freelance writer based in Washington, D.C.