Oil spill science: The jellyfish graveyard

[depakid]

Science journalist Mark Schrope is aboard the research vessel Pelican, which is spending the week studying the Deepwater Horizon oil spill in the Gulf of Mexico.
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As I write, the Pelican is about 15km from the spill site, which we can see now in the dark lit up like a small town in the distance.

We started the day near South Pass, the beginning of a channel that winds through the marshes all the way to New Orleans. It's an area scattered all around with the smaller oil platforms used in shallow waters. The National Institute for Undersea Science and Technology team chose this site for study last week based on early reports of oil washing ashore nearby, though the water is clear here for now.

After taking water samples and prepping some of the other equipment we were underway again. A few kilometres out I began to see the first signs of oil in the thin, light brown form it takes after treatment with surfactants. The response team has pumped and sprayed more than a million litres of these chemical brews into the water to react with and breaks up the oil into a form that sinks more easily. What impacts these surfactants may have on marine organisms is one of many open questions.

At our second stop, the team took its first sample of the soft, exceedingly sticky sediment below using a box core lowered by cable. This spring-loaded steel contraption, about the height of a refrigerator, brings up a cube of the seafloor 50 cm square and 60 cm high. There were jokes about whether a moray eel might be hidden in the core waiting to latch onto someone's hand, as happened with a small one last week. But alas, there would be no such entertainment today.

From the main sample the team took smaller circular cores for later analyses. Some, for instance, will go to a group that will study the DNA of organisms found in the sediment, not likely affected by oil yet, as a baseline for studies of eventual oil impacts.

By the afternoon we had made it to a site called Mississippi Canyon Block 118, or MS118, our current location. This is a research site that NIUST and others have been working at for about 10 years, studying the geology and biology of methane hydrates. Hydrates are ice formations common on and below certain parts of the deep sea floor that form within a specific band of high pressure, low temperature conditions, trapping methane and other gases in the process.

One of the key goals for the long-term research at MS118 has been better understanding of conditions that can lead to hydrate destabilization and rapid release of methane, which may have caused the well blowout that instigated the big spill. Hydrate formation is what caused the containment device lowered onto the well leaks to clog.

Here at MS118 we found much more of the dispersed oil and occasional clumps of thick, gooey, intact oil. Beyond that the most striking thing is the presence of countless small dead jellyfishes known as by-the-wind sailors, or Velella vellela, and known to be susceptible to oil. Normally these animals, about the size of two fingers together, are blue and float on the surface with a triangular sail rising above the water t. But those we see here are transparent and floating upside down, many stained with oil.

After finishing here late tonight, we'll move nearby to drop a device called the high-frequency acoustic recording package, or HARP, to the seafloor, about 1600metres below. There it will sit and record marine mammal sounds in the region before retrieval by other researchers a few months from now.

More: http://blogs.nature.com/news/thegreatbeyond/2010/05/oil_spill_science_the_jellyfis.html

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[voteearlyvoteoften]

1. Scientists on the spot

Thank you for your work. Good luck out there.

[chill_wind]

2. K & R. n/t