Microbes consuming oil from the Gulf of Mexico's BP spill deplete oxygen levels when they die, raising the threat of an expanded "dead zone," which endangers some marine life. Now scientists are using years of dead-zone data to determine whether the dangerous region grew after the spill.
© 2010 National Geographic; partially funded by NSF; field producing and videography by Fritz Faerber
WHEN THE BP OIL SPILL IN THE GULF OF MEXICO BEGAN IN APRIL, NATURALLY OCCURRING MICROBES BEGAN THEIR WORK, GOBBLING UP SOME OF THE OIL WHEN THE MICROBES DIE, OXYGEN IN THE WATER IS USED UP AS THEY DECOMPOSE.
SCIENTISTS HAVE BEEN CONCERNED THAT, IF THIS OCCURED IN MASS QUANTITIES AS A SERIOUS CONSEQUENCE OF THE OIL SPILL, IT COULD CREATE HYPOXIC OR ‘DEAD ZONES’ OF LOW OXYGEN IN THE WATER.
SOUNDBITE: MIKE ROMAN, LAB DIRECTOR, UNIVERSITY OF MARYLAND CENTER FOR ENVIRONMENTAL SCIENCE
“What happens when you have no oxygen on the bottom, first of all it kills all the critters that can’t swim away: Worms, crabs in the sediment. But it also makes the habitat unavailable, it’s like a false bottom. So they can’t swim down to the bottom to avoid predators. They can’t get down to cooler waters, so they’re up in the surface waters, where it’s lighter, so they’re more susceptible to predators, but it’s also warmer so their metabolism is higher and they require more foods.”
MIKE ROMAN AND HIS COLLEAGUES AT THE UNIVERSITY OF MARYLAND’S HORN POINT LABORATORY STUDY THE DEAD ZONE IN THE GULF OF MEXICO THAT HAS OCCURED EVERY SUMMER FOR OVER 20 YEARS AND EXTENDS ALONG THE COAST FROM THE MOUTH OF THE MISSISSIPPI RIVER TO TEXAS.
THIS DEAD ZONE IS CAUSED BY FERTILIZERS AND OTHER CHEMICALS BEING WASHED INTO THE RIVER. THEY HAVE DATA GOING BACK TO THEIR FIRST STUDY IN 2003.
THIS YEAR, THEY LOOKED FOR ANY CHANGES DUE TO THE SPILL.
SOUNDBITE: “We measured these plants and plankton and fish, and the distribution looked about the same as they would have in these other years. There was low oxygen in the water in the bottom. They avoided it. The area wasn’t particularly large compared to what was predicted, we had sensors that detected oil. We didn’t see any oil.”
ROMAN AND HIS COLLEAGUES USE AN ARRAY OF SENSITIVE DEVICES TO MEASURE OXYGEN LEVELS, SALINITY, TEMPERATURE, AND POPULATION DENSITY OF FLORA AND FAUNA.
MANY OF THE MEASUREMENTS COME FROM A DEVICE CALLED A SCANFISH, TOWED BEHIND A VESSEL.
“this is the chlorophyll fluorescent sensor… “
ONE DEVICE THE SCIENTISTS ADDED TO THE SCANFISH CAN COUNT ZOOPLANKTON – A KEY INDICATOR OF SEA HEALTH.
SOUNDBITE: JAMIE PIERSON – ASST. RESEARCH PROFESSOR, UMD CENTER FOR ENVIRONMENTAL SCIENCE
“As a zooplankton ecologist, I am biased, but I also feel like it’s an integral part of the food web. It’s directly between the primary producers, like the algae that uses the sun for energy and the fish, which are commercially and ecologically important for various reasons. So the zooplankton sort of mediate the flow of energy and flow of materials from primary producers up to the larger animals.”
PIERSON SAYS EARLY DATA DOESN’T INDICATE ANY DRAMATIC CHANGE DUE TO THE OIL.
SOUNDBITE: “At first glance it was a lot of happy healthy copepods out there.”
ROMAN, PIERSON AND THEIR FELLOW RESEARCHERS STILL HAVE A LOT OF DATA TO ANALYZE TO DETERMINE IF THE OIL AFFECTED THE HYPOXIC ZONE THEY’VE BEEN STUDYING FOR YEARS. HOWEVER, THEIR STUDY CAN’T ANSWER QUESTIONS ABOUT THE REST OF THE GULF.
SOUNDBITE , ROMAN “We were fortunate to have this five years of baseline data. It’s too bad they didn’t have the 5 years of baseline data for where a lot of the oil went. So if you are going to have all of this exploration for oil in the Gulf, you should have a monitoring program in place.”
ROMAN THINKS IT’S UNLIKELY THERE IS A VERY SERIOUS DEAD ZONE IN ANOTHER PART OF THE GULF DUE TO THE BP SPILL BECAUSE HE FEELS SCIENTISTS WOULD HAVE FOUND IT BY NOW.
HE DOES HAVE CONCERNS ABOUT THE EFFECT OF THE OIL SPILL ON THE FOOD WEB.
ROMAN SOUNDBITE: “The thing that I worry about is the little things that eat the bacteria, that get eaten by bigger things, get eaten by bigger things, some of those oil compounds will be around the food web for awhile and may affect the reproduction behavior and those are the things that should be studied now. “