NEWS NATURE|Vol 437|22 September 2005

462

After Katrina: tracking the toxic floodBATON ROUGEThree weeks after Hurricane Katrina ravagedthe coasts of Mississippi and Louisiana,marine researchers are starting to assess thesafety of fish and shellfish exposed to toxicflood waters in the Gulf of Mexico.

The flood waters are teeming withEscherichia coli bacteria and a wide range ofchemicals (see Nature 437, 301; 2005). Andengineers are pumping the toxic mix out of thecity towards the Gulf coast. With its shrimp,oyster, crab and flat-fish stocks valued ataround $3.1 billion, the coast is one of the rich-est fishing grounds in the United States.

Shailer Cummings of the National Oceanicand Atmospheric Administration led a food-safety team into the Gulf last week for a three-day expedition on board the research vesselNancy Foster. Until then the boat was beingused to check the safety of the region’s majorports, doing soundings to check for obstruc-tions under the water, among other tasks.

Cummings had just two days to organize theexpedition — a huge challenge under normalcircumstances and more so as personnel werein such short supply. “When you try to get aresearch team from a distressed area they arehungry, stressed and looking for their familylike everyone else,” he says. So he recruited ateam from the Northwest Fisheries ScienceCenter in Seattle, Washington.

His team of some 15 scientists collectedshrimp, oysters and Atlantic croakers — a

common ground fish — and sent them to aSeattle laboratory to be tested for bacterialcontamination and pollutants. Aware of therisk of a second public-health disaster in thewake of the hurricane, the researchers workedaround the clock. “Nobody sleeps,” Cummingstold Nature after three tough days aboard theNancy Foster. “We’re doing this to make surethe food supply is safe.”

On their tour through the Gulf, the crewtook samples from the muddy plume that hasspread from the Louisiana coast over hun-dreds of square kilometres. Katrina muddiedthe water by washing sedimentsfrom the Mississippi into the sea,explains Cummings. And thefresh water is sitting on top of thesalty water, spreading “like tea on a tabletop”.

So far, the team has seen no evidence of thealgal bloom that might result from the fresh-water influx, and the circulation pattern of thewater seems normal. But “we don’t knowwhat’s in the water”, says Cummings.

As well as sampling water and sediment forpathogens and chemicals, the researchers dissected, prepared and labelled fish samplesfor storage until they could be tested back inSeattle. It was close, feverish and smelly work.The liver and bile will be tested for fat-basedcontaminants such as polyaromatic hydro-carbons. The gut and gill will be tested forpathogens, and the muscle will be tested

for mercury and other contaminants. “It’s an unprecedented situation,” says Tracy

Collier, head of the ship’s wet lab and directorof Environmental Conservation at the North-west Fisheries Science Center. “We’re trying tosample as broadly as we can,” he explains, todetect anything that might harm people.

The results will not be ready until the end ofSeptember. But it is unlikely anyone will get illin the meantime, says Bo Boehringer of theLouisiana Department of Wildlife and Fish-eries, because no fishing is likely to take placefor many weeks. Katrina has brought the

fishing community in the regionto a standstill. Boats and piers have been destroyed, ice housessmashed and fish-processing cen-tres damaged. US authorities esti-mate that about 4,800 fishermen

in the area are now out of work.Although serious attention is being paid to

food safety, there is also concern that Katrinahas damaged fish and shellfish stocks. Floodwater has covered oyster beds along a stretchof inland bays with up to a metre of mud, andthe oysters have suffocated.

Some wildlife seems to be bouncing back,however. Biologist Melody Baron was onboard the Nancy Foster to watch for marinemammals in distress. On her third 12-hourshift she said she had seen turtles and dolphinsbehaving normally. ■

Adrianne Appel

The research vessel Nancy Foster has beensampling the Gulf ofMexico to gauge flood pollution.

NO

AA

“We’re makingsure the foodsupply is safe.”

22.9 News 462-463 MH 20/9/05 2:25 PM Page 462

Nature Publishing Group© 2005