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USF scientists comparing Deepwater Horizon oil spill and a Mexican disaster in 1979 (w/video)

For 40 days, scientists aboard a Florida-based research vessel trolled the Gulf of Mexico for signs of the past, hoping to discover hints of the future.

Now their ship has landed back in St. Petersburg, full of sediment samples and slivers of fish. They think those items will help them predict the long-term effects of the 2010 Deepwater Horizon disaster.

The scientists expect to take months analyzing all of the specimens now stored in freezers at the University of South Florida College of Marine Sciences in St. Petersburg. But they have some preliminary findings that came from just keeping their eyes open.

Along the Mexican coastline, in an area where in 1979 a similar oil-drilling disaster occurred with a rig called Ixtoc 1, they found tar balls and other oil residue a few inches below the surface of the shoreline.

"Sometimes you'd break these tar balls open and there'd still be liquid oil inside," said one of the USF scientists, Patrick Schwing. "It's not even degraded yet, 37 years later."

They also found stretches where mangroves should be growing, yet are not, he said. More slabs of weathered oil, looking like tarry asphalt, appeared to be to blame.

"There are patches that are just barren," Schwing said. "In those areas we found those large asphalt coatings underneath about 2 or 3 inches of sand."

The voyage of the R/V Weatherbird, a 118-foot research vessel, took 13 scientists from USF and other institutions and seven crew members all over the gulf to collect thousands of samples from both spill sites. The frozen samples represent what Schwing called "the largest collection of Gulf of Mexico sediment and fish tissue samples in one place."

Scientists used 5-mile-long nets with thousands of hooks to catch fish for examination. This fishing was anything but fun.

"During the day, the temperature got to be over 100 degrees, and you're standing on a steel deck out in the middle of the ocean, just wishing for a breeze," said Susan Snyder, a Ph.D. candidate. "You work really long hours, and your feet are almost always wet."

There were other perils, as well. "You spend all day cutting up fish, and you don't want to eat seafood for dinner," she said.

Scientists jokingly call a trip like this a "mud and blood cruise," because they collect blood and various organs from the fish they catch, as well as dig up muddy soil samples from the sea bottom. The layers show what has happened to the bottom over time, just like in an archaeological dig.

The parallels between the Mexican disaster and Deepwater Horizon (the subject of a movie opening next weekend) are what attracted the USF consortium to investigate the earlier spill, using part of a $20.2 million grant.

The Ixtoc 1 spill occurred in a section of the gulf called the Bay of Campeche, just north of the Mexican coast. Problems with drilling muds led to a blowout at the government-owned rig, which caught fire and collapsed, just like BP's Deepwater Horizon rig off the coast of Louisiana six years ago. Deepwater Horizon blew up because of a pipe that buckled under pressure and a blowout preventer that failed.

The fire and scattered debris from Ixtoc 1 made capping the well so difficult that it continued spewing for nearly a year, dumping more than 3 million barrels of oil into the gulf. The spill spread out along the gulf coast, reaching up to Texas and Louisiana.

In BP's case, the depth of the well at 5,000 feet below the surface left the company unable to cap the well for three months, during which the rig spewed 4.2 million barrels of oil from the wellhead. Oil spread across the Gulf Coast, tainting not just Louisiana but also Mississippi, Alabama and Florida Panhandle coastlines.

After the Ixtoc spill, a Texas scientist who studies coral, Wes Tunnell Jr., began documenting where the oil washed ashore. He got a research grant, but then a tropical storm hit Texas, pushing the oil away from shore, and the money dried up.

But Tunnell kept taking student groups back for years afterward, and kept an eye on those spots, watching as oil mats that started out 210 feet long and 12 to 15 inches thick weathered down to about 10 percent of that size. He was able to guide the USF group right to those same spots.

"We didn't learn much at all about Ixtoc because it wasn't funded," Tunnell said. "But we're learning a lot from Deepwater Horizon, and not just about the oil spill but about the Gulf of Mexico as a whole."

While there's no proof yet that the oil they found is from Ixtoc, the circumstantial evidence seems strong to Schwing and the others. They expect to run laboratory analyses on the samples they collected to get the final proof, even as they search the fish samples for signs they are still being affected by the spill.

Before Deepwater Horizon, much of the gulf was a mystery to scientists. Now, by comparing Deepwater Horizon with Ixtoc, the scientists believe they can plot out a course for dealing with what's going to happen next, especially if there's another offshore oil disaster.

"Our goal here," Schwing said, "is to establish what is the new normal."

Times photographer Lara Cerri contributed to this report. Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.

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