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The Reason We’re Here
December 09, 2010 (posted December 10, 2010)
by Ken Kostel
This evening, Alvin brought up a piece of coral from the seafloor that, as Erik Cordes from Temple University put it, did not look the way it should. There was little healthy tissue covering the coral skeleton, and a dark substance covered much of the coral stem. Very quickly, scientists clustered around it, all trying to understand what happened to the coral.
The coral was sampled from a location near the Deepwater Horizon oil well and in the pathway where scientists think a plume of oil from Deepwater Horizon well flowed in the deep sea. But no one could say for sure just by looking at it whether the damage was caused by oil from the Deepwater Horizon spill, or even if it was caused directly by oil.
The fact is, many of the animals that live at the bottom of the Gulf of Mexico have to adapt to low levels of oil exposure, some caused by humans and some that occur naturally. Of course, Deepwater Horizon spilled a huge amount of oil, but one sad-looking piece of coral is not proof of widespread ecological damage. It’s a sign of something, but of what, is hard to say. Oil spills are very difficult things to study. This is an initial piece of evidence—one of many types of evidence across many locations—that scientists must find, collect, analyze, and assemble to determine the impacts of this unprecedented oil spill.
As I’ve heard many scientists say over the past six months, “Every oil spill is different.” Here’s a list of the main reasons why.
Oil is not a single substance, but a complex mixture of chemicals and compounds that differs depending on where in the world the oil comes from.
Oil released into one ecosystem, such as a marsh, will behave very differently than oil released into another, such as a rocky beach. And that oil will not remain the same as it was when it came out of the ground.
Oil is spilled into the environment all the time, and not just as a result of human activity. (In fact, less than half of the oil in the ocean comes from human activity, and only about 10 percent of that comes from spills.) Some sources of oil trickle, some gush; some are short, some spread out over years.
The Deepwater Horizon spill was special for many reasons. One was the amount of oil that spilled into the ocean in a short burst. By the time it was stopped, after about three months, some 152 million gallons of oil leaked from the ruptured well, one of the largest spills in history. The leak also occurred one mile beneath the surface of the ocean. No oil spill of this size has ever occurred at such a depth. Finally, the spill happened in a place that is home to a wide diversity of plants and animals. It’s also a place where many human activities go on—including oil drilling, fishing, and recreation—often competing with one another and with nature.
In one way, it was eye-opening to watch so many smart people be so excited and yet so stumped by one sickly branch of coral. But when you think of all the ways that an oil spill can affect ocean life, it’s not surprising at all.
Once oil enters the water, the different chemicals in the oil begin acting independently of one another. Some parts are soluble, meaning they can dissolve in water. Some parts are heavy and sink to the bottom. The parts in oil that float make a slick on the surface. Over time, the oil moves and changes and begins interacting with the environment in even more complex ways.
So no one knows yet exactly what happened to all the oil that was spilled.
And there are many more factors to figure in. Some animals can survive an oil spill better than others. And the Gulf is also not a single place; it had many different types of ecosystems. Some places will almost certainly be changed forever, but even these might one day be considered healthy ecosystems.
No one knows exactly how the oil has affected the Gulf or how long the effects will last.
There is no way to know from looking at one piece of coral. It will require many scientists putting together many pieces of the puzzle to begin to get a picture and learn the lessons of what happened here in the Gulf.
Read the new Hot Topic
Gulf of Mexico
If there is any lesson to take from the Gulf of Mexico it’s that even someplace as close to shore and as relatively well studied as this can still offer some surprises. The Gulf is easy for scientists to get to, but still very complex. Learn more »
Read the new Interview
Helen White: Microbes are an important and amazing part of the deep-sea ecosystem. They also play a key role in the ability of the deep ocean to respond to the oil spill. Helen White studied an oil spill that occurred in 1969 in Buzzards Bay and that still affects coastal ecosystems today. Read the interview »
Listen to the audio
You are clear to dive
Listen in as Alvin electronic technician Korey Verhein in Atlantis’ Top Lab communicates with pilot Mike and the many other people on the ship whose job it is to make sure the sub launches safely each day.
[NOTE: This audio is edited to remove long breaks between messages. These communications actually take place over about 30 minutes.]
Terms you’ll hear:
A-frame: The A-shaped crane on the stern of Atlantis that launches and recovers Alvin. Avon: The small boat used to carry support divers during launch and recovery of Alvin. Dampers: Large shock absorbers that keep Alvin from swinging side-to-side while suspended from the A-frame. Dog House: The area above the stern deck where the A-frame controls are located. Ducer (Transducer): A device used to communicate between Atlantis and Alvin while Alvin is submerged. Elevator: A device used to send instruments to the seafloor and retrieve them later. On this mission, Alvin dived to an elevator holding a time-lapse camera. Swimmers: The support divers who help launch and recover Alvin. UQC: Underwater communications system used to talk between Alvin and Atlantis.
