By Josh Fischman

The ecological effects of the 2010 Deepwater Horizon oil spill are still largely unknown. Senior writer Josh Fischman is on the research vessel Endeavor in the Gulf of Mexico with a team of university scientists seeking answers. He is filing reports from the ship.

One hundred and twenty miles south of the Mississippi Delta—The Endeavor is moving at 1 knot through a thin but wide slick of oil. The sheen glints in the water for a hundred yards or more around the ship. “It’s a little disturbing when you see fish swimming underneath it,” says Nigel D’Souza, a postdoctoral researcher at Lamont-Doherty Earth Observatory, part of Columbia University. “I was on deck earlier collecting some of the oil with a bucket, and some mahi-mahi swam by. It makes you wonder how much of this stuff is in the food chain, and in what form.”

When I pointed out that he was on the ship to help answer that question, he said, “Yes, well, this makes it seem more urgent.”

Urgency is never lacking on the Endeavor, where science is a mixture of precision and controlled frenzy. Ship time is staggeringly expensive, so the 17 scientists and technicians on board have crammed round-the-clock experiments and sample-collecting into fewer than 10 days at sea. On July 5 they are off the ship because other researchers are waiting to use it.

But the rush to get everything done doesn’t negate the need to get it right. Sampling bottles are sent 1,200 meters down to the bottom of the gulf, and temperature, oxygen levels, and the pigment chlorophyll (derived from phytoplankton) are measured every moment. The bottles are opened remotely at very specific depths. Back on the surface, in the ship’s main lab, recovered water is filtered for gases like methane and the chemicals that reveal the presence of microorganisms. A highly specialized instrument called a flow cytometer can count the number of single-celled creatures in a droplet of water. All of this, and more, is done over and over again, to compare different locations at different depths at different times of day.

“We have to push pretty hard,” says Chief Scientist Joseph Montoya, a biogeochemist from the Georgia Institute of Technology. Every day, Montoya figures out how many nets, drift traps, sampling bottles, and bottom-sediment cores can be taken from each site, and posts a plan that has scientists and crew members lowering equipment over the side and recovering it at all hours of the day and night. He and I share a cabin, and I’m sure he slept for five hours at a stretch—once. “If you snap a picture of Joe cat-napping,” says one of his students in the science contingent, “you win a prize.”

Everyone was awake as last Monday night ticked into Tuesday morning and the Endeavor arrived at the Deepwater Horizon site. The ruined wellhead that blew apart in April 2010 was some 1,600 meters below us. From the starboard side of the boat, as Captain John Wilder held the 185-foot ship steady in the currents and wind, scientists paid out a wire that held a cluster of sampling bottles called a CTD. Then Montoya and Patrick Quigley, the botswain, headed for the fantail, at the back of the ship, crowded with so much scientific equipment it was hard to walk. As Quigley attached shackles and lines and directed hydraulic hoists and heavy-powered winches, two sediment traps went over the side and down to the bottom, where they will collect samples for a year, anchored by big iron train wheels. An underwater camera went over next, followed by a “robotic” CTD that dives and samples free of the ship; we will collect it—if its radio beacon works—on our way back to port.

“Look at all this room!” called Quigley, standing in the middle of the now-empty fantail.

The Endeavor then turned southwest and farther into the Gulf, toward the site the scientists called GC 600, where oil and methane seep from the ocean bottom naturally—a good comparison with the unnatural Deepwater Horizon. The ship arrived at 10:30 Tuesday evening and the routine began again.

Well, it was the routine plus, which meant minus more sleep. Melitza Crespo-Medina, a microbiologist, postdoctoral researcher, and leader of what has been dubbed “the mud people” from the University of Georgia, had to find active gas or oil plumes on the sea floor, so Montoya and the other scientists would know where to focus their sampling. That meant a fine-grained sonar survey starting at 4 in the morning; the sound waves can reveal streams of bubbles from mud that’s more than 1,000 meters below the ship. That evening, Crespo-Medina sent a device to the bottom to bring back tubes of mud and sediment. These meter-long cores need to be extracted from the machine, cut into sections, and looked at for hydrocarbon content and signs of bacterial activity. Crespo-Medina was up for 24 hours straight, slept for three hours, then went at it again.

Thursday began with a problem. The sonar survey hadn’t homed in on a plume, and then Joy Battles, a graduate student who works with Crespo-Medina, announced that levels of methane in the water were on the low side. Seeps flow irregularly, and we seem to have caught this one napping. Bad news for a project aimed at measuring the effects of natural seeps. Montoya is worried that further experiments where we’ve been working are a waste of time.

And we’ve been working that area, around the edges of GC 600, because the middle—which had been bubbling nicely on previous visits—is now in a “no go” zone, a box on the map indicating we can’t sample there. Another scientist has a package of instruments at the bottom, and is afraid our coring might disturb it.

The solution is, of course, more work and less sleep. Getting permission to edge into the “no go” box, the scientists begin redoing surveys done yesterday. Crespo-Medina does another painstaking sonar pass over the bottom, and Battles combs new water samples for signs of gas. Another cost of doing this extra work is the team gives up a planned trip to a nearby site that could hold a new seep. But better the devil you know is the consensus aboard ship.

The gamble pays off. Just after midnight Thursday, as the ship was completing another 1,200-meter surface-to-bottom probe, Battles bursts into the main lab to announce methane levels at the new target shot way up. They were, in fact, about 15 times higher than the levels we were seeing yesterday. And oil slicks began drifting by. Montoya put down his laptop and clapped.

This was not a medical miracle, no cure for cancer, but it meant the central premise of the project, comparing the natural to the unnatural, would work. A delicately placed core even returned some oil-impregnated mud from the bottom, droplets that winked back at Crespo-Medina as she illuminated them with a flashlight.

“I found the methane,” she sang softly and repeatedly, as she worked on deck drawing water from the sample bottles her colleagues had sent into the deep.