The ecological effects of the 2010 Deepwater Horizon oil spill are still largely unknown. From today until early July, senior writer Josh Fischman will be on the research vessel Endeavor in the Gulf of Mexico, with a team of university scientists seeking answers. During the next two weeks he will file a series of reports from the ship about their findings. This first dispatch comes from land, as the ship prepares to embark.

The Deepwater Horizon rig on fire after the blowout. (U.S. Coast Guard / Creative Commons)

The Gulf Coast is clean, the tourism ads say. Oil has been dispersed, wildlife has been scrubbed, the beaches show white sand and blue water. And tourists have been flocking back to the Mississippi, Alabama, and Florida coasts; hotel room bookings are way up over last year. That megafauna, at least, has made a hearty recovery from the nearly 5 million barrels of oil that the Deepwater Horizon rig dumped into the region in 2010.

When it comes to organisms that can’t be seen with the naked eye–but which form the foundation of Gulf of Mexico ecology–it’s a much different, and potentially much messier story. “Micro-organisms like algae are the giants of the world’s biological productivity,” says Samantha (Mandy) Joye, a biogeochemist from the University of Georgia. “In the ocean, for instance, they produce half of the oxygen. And in the Gulf, we don’t really know  what’s happened to them. It’s almost criminal that we don’t know this.”

Joye is one of a group of scientists bent on finding out. She’s part of a multi-year, multi-institution project to map the impact of oil and gas in the Gulf, called ECOGIG. It means going hundreds of miles in research ships and sampling the ocean from the top to the sea floor. Literally, says Ray Highsmith, a marine scientist at the University of Mississippi and director of the project, “we have to get to the bottom of this.”

Oil and water mix quite often in the Gulf. And most of the time people have nothing to do with that. Small, slow bubblers in the seafloor, known as seeps, have been releasing oil for millions of years. Indeed, organisms like algae and water-borne bacteria have evolved in balance with that regular bubbling.

In April of 2010 the mixture was sudden and much much bigger. The Deepwater Horizon oil rig spill dumped 4.9-million barrels of oil into the Gulf before the wellhead was capped in July, according to a federal science panel, the Flow Rate Technical Group. The seepage that the Gulf gets naturally is about 3 percent of what poured out of the busted wellhead everyday. And that’s not even counting gasses, like methane, that flowed from the pipe. Joye has estimated they were equivalent to an additional 1.5 million to 3 million barrels of oil.

Of the oil itself, about 800,000 barrels, or 17 percent, were captured by containment efforts. The remaining 4.1 million barrels hit the Gulf: Some of it was burned, some skimmed, some floated around, some washed up as tar balls on beaches, some sank to the sea floor, and some was taken up by these tiny creatures. No one is sure how much went where. But when it comes to the microscopic world, “there is a very delicate balance among these organisms and when you inject millions of gallons of oil, you upset that balance big time,” says Joye.

A carbon signature from the Deepwater Horizon spill has been found in Gulf plankton, indicating that the oil has been taken up by the microscopic animals. But to what effect? People have argued that because the Gulf is filled with natural seeps, the organism can handle oil and even live off it. But the ECOGIG researchers have already found that an abundance of oil does not mean a bloom of oil-eating microbes. In fact, growth of the microbes is limited by the amount of other food sources, like nitrogen and trace metals such as copper. Add hydrocarbons like oil and you do get a bloom–followed by a population crash when those other nutrients run out. The cycle of “bloom and bust” could limit the Gulf’s natural ability to clean up the man-made mess.

The RV Endeavor is a 185-foot long floating laboratory. (Image courtesy URI)

To get a handle on that cycle, and see what’s happening on the surface and below it, the research vessel Endeavor, operated by the University of Rhode Island and shared with research scientists at institutions across the country, will leave Gulfport, Mississippi, to cruise around the spill site in the Gulf of Mexico during the next several weeks. Scientists will be digging into the ocean floor, and towing nets just below the surface, collecting microbes from seeps, a “mud volcano,” and from sites around the spill, comparing the natural world to the disaster.

Sites where Endeavor will take samples. The Deepwater Horizon rig was in the top right cluster of markers.

One of the first stops will be a seep with an unremarkable name–GC600–that doesn’t begin to capture its significance. “It’s one of the largest, if not the largest, seep in the Gulf of Mexico,” says the chief scientist on the ship, Joseph Montoya, a biogeochemist from the Georgia Institute of Technology. “In calm weather, you can see oil bubbling up to the surface and forming persistent slicks.”  And that makes it a great place to study the effect of oil as it moves up and down in the water. You can follow the ship’s journey to other sites in the Gulf by clicking on this map, which shows the vessel’s current location.