Hurricanes’ full havoc hasn’t yet been felt storms, the concentration of algae rose to four to six times typical values and re- mained greater than normal more than a year later, Paerl says.

After the first bloom of algae died and sank, its decomposition sopped up much of the oxygen along the bottom of the sound for a month or so, significantly af- fecting all local life.

“The slower [the animals] were, the worse their predicament was,” says Paerl. At some sites, most ovsters and

Forget about a mere one-two punch. When Hurricanes Dennis, Floyd, and lrene pummeled North Carolina in the fall of 1999, they delivered a three-punch combination that for years to come may disturb coastal ecosystems there and disrupt fishing in the Atlantic Ocean.

The three hurricanes struck the east- ern United States within a 6-week period. Along their paths, they dumped a total of 1 meter of rainfall upon areas that drain into North Carolina’s Pamlico Sound. That body of water-a lagoon protected by the barrier islands rimming the state’s shore-is a major fish and shellfish nurs- ery for the entire Atlantic coast, says Hans W. Paerl, a marine ecologist at the University of North Carolina’s Institute of Marine Sciences in Morehead City. These spawning grounds ultimately are the source of more than 90 percent of the fish caught by North Carolina’s commer- cial fishers, he notes.

As sediment- and nutrient-rich flood- waters spilled from the North Carolina piedmont in the wake of the hurricanes, they radically altered the environment in Pamlico Sound, Paerl notes. More than 75 percent of the sound’s brackish water was flushed into the Atlantic Ocean as fresh water from Piedmont rivers filled the sound. The resulting spike of dis- solved nutrients in the sound fed algae blooms. In the months following the

Astronomers get the For all their mind-boggling effects on

geometry, warping the very fabric of space and time, black holes are governed by two just properties-mass and spin.

Although these superdense objects don’t emit light, their mass can be meas- ured with relative ease if they are partnered with a visible star. Astronomers simply record how much of a tug a black hole exerts on its companion. Determining whether a black hole rotates has proven much more of a challenge. Astronomers r e ported last week strong evidence that black holes spin like whirling dervishes, dragging

clams died and blue crab populations dropped by 90 percent. Paerl’s team re- ports its findings in the May 8 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES.

There were few fish kills in the sound because the initial pulse of fresh water from Hurricane Dennis drove the fish in- to the Atlantic Ocean-right into the nets of the waiting fishermen. This fish stampede led to some of the best catch- es in years, but these commercial suc- cesses don’t indicate the hurricanes’ ef- fects on upcoming generations of fish, notes coauthor Larry W. Ausley, a ma- rine biologist at the North Carolina De- partment of Environment and Natural Resources in Raleigh.

Although the ecosystems in Pamlico Sound are resilient, it may take years for them to fully recover, and it may be a decade or more before the full effects on fish populations are seen, notes Ausley.

spin on black holes the black hole, never to be seen again.

From the region around GRO 5165540, the satellite detected X rays that flicker 300 times per second. The observed ra- pidity is just what astronomers would ex- pect from a blob of hot gas orbiting 64 km from the black hole. The satellite, however, also recorded an even faster flickering-an X-ray signal winking on and off 450 times per second.

A radiating blob of gas orbiting a black hole is like a lighthouse beacon sweeping past Earth hundreds of times per second, suggests Strohmayer. The closer the blob

Sediment-rich floodwaters gushing from southern Pamlico Sound after Hurricane Floyd are swept northeast (arrow) by the Gulf Stream in this Sept. 23, 1999, image.

Other scientists in the region had been concerned that petroleum prod- ucts, pesticides, and agricultural cherni- cals flushed into Pamlico Sound would end up trapped in the sediments there. Damian Shea, a toxicologist at North Car- olina State University in Raleigh, says that the surge of floodwaters did, in fact, boost the concentrations of many such chemicals in the sound’s water for a cou- ple of weeks. However, a program that monitored the sediments in the sound during the 18 months following the hurri- canes showed that those increases didn’t translate into additional long-term con- tamination. -S. Perkins

gets to the black hole, the faster it orbits. The most rapid oscillation detected

by Rossi can best be explained by blobs of gas that are orbiting 15 km nearer to the hole than indicated by the slower flickering, he says. The material could maintain itself at this close distance only if the black hole spins, Strohmayer as- serts. He explains that a spinning black hole alters spacetime in such a way that matter can have a stable orbit at a clos- er distance than it could around a non- rotating black hole.

Strohmayer reported the findings at a meeting of the American Physical Society in Washington, D.C., and will present fur-

Goddard Space Flight Center in Greenbelt, % Md., and his colleagues examined the X- ray flashes emitted by stellar matter 4 plunging into a nearby black hole. Known as GRO 5165540, this system lies 10,000 L light-years from Earth and consists of an ordinary star orbiting a black hole about 6.3 times as massive as the sun. f

black holes spin,” says M. Cole& Miller of the University of Maryland in College Park

That’s not to say the finding comes as a surprise, A stellar black hole forms when a star at least 10 times the sun’s mass col- lapses to an infinitely dense cinder. Con- servation of angular momentum dictates that if the star was rotating. the resulting

A blob of gas circling a stationary black Simulation of a black hole sucking in hole this massive can’t maintain itself matter from an orbiting disk of gas {white in an orbit with a radius smaller than and blue rings]. Gap between the disk 64 kilometers. If the orbiting material ven- and the hole represents the smallest tures any nearer, it’s doomed to fall into stable orbit that the gas can haoe.

black hole should rotate even faster. Still, with so few clues available to

tease out the behavior of black holes, demonstrating the rotation “is big news,” Miller says. -R. Cowen

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MAY 12,2001 SCIENCE NEWS, VOL. 159 293