LAKE MEAD, Nev. — On this brisk, glittering morning, a flat-bottomed boat glides across the massive reservoir that provides Las Vegas its drinking water. An ominous rumble growls beneath the craft as its two long, electrified claws extend into the depths.
Moments later, dozens of stunned fish float to the surface.
Federal scientists scoop them up and transfer them into 50-quart Coleman ice chests for transport to a makeshift lab on the dusty lakeshore. Within the hour, the researchers will club the seven-pound common carp to death, draw their blood, snip out their gonads and pack them in aluminum foil and dry ice.
The specimens will be flown across the country to laboratories where aquatic toxicologists are studying what happens to fish that live in water contaminated with at least 13 different medications — from over-the-counter pain killers to prescription antibiotics and mood stabilizers.
More often than not these days, the laboratory tests bring unwelcome results.
But people aren't the only ones who consume that water. There is more and more evidence that some animals that live in or drink from streams and lakes are seriously affected.
Pharmaceuticals in the water are being blamed for severe reproductive problems in many types of fish: The endangered razorback sucker and male fathead minnow have been found with lower sperm counts and damaged sperm; some walleyes and male carp have become what are called feminized fish, producing egg yolk proteins typically made only by females.
Meanwhile, female fish have developed male genital organs. Also, there are skewed sex ratios in some aquatic populations, and sexually abnormal bass that produce cells for both sperm and eggs.
There are problems with other wildlife as well: kidney failure in vultures, impaired reproduction in mussels, inhibited growth in algae.
"We have no reason to think that this is a unique situation," says Erik Orsak, an environmental contaminants specialist with the U.S. Fish and Wildlife Service, pulling off rubber gloves splattered with fish blood at Lake Mead. "We find pretty much anywhere we look, these compounds are ubiquitous."
* In a broad study still underway, fish collected in waterways near or in Chicago; West Chester, Pa.; Orlando, Fla.; Dallas; and Phoenix have tested positive for an array of pharmaceuticals — analgesics, antibiotics, antidepressants, antihistamines, anti-hypertension drugs and anti-seizure medications.
* That research follows a 2003 study in northern Texas where every bluegill, black crappie and channel catfish researchers caught living downstream of a wastewater treatment plant tested positive for the active ingredients in two widely used antidepressants — one of the first times the residues of such drugs were detected in wildlife.
* In several recent studies of soil fertilized with livestock manure or with the sludge product from wastewater treatment plants, American scientists found earthworms had accumulated those same compounds, while vegetables — including corn, lettuce and potatoes — had absorbed antibiotics. "These results raise potential human health concerns," wrote researchers.
* Blood and liver samples of bull sharks in Florida's Caloosahatchee River, a nursery area for juvenile bullsharks and home to six wastewater treatment plants, are being tested for the presence of an array of medications this winter. Of the first 10 sharks sampled, nine tested positive for the active ingredient in an antidepressant.
* In Colorado's Boulder Creek, 50 of the 60 white suckers collected downstream of Boulder's wastewater treatment plant were female, compared to about half of them upstream.
Elsewhere in the world — from the icy streams of England to the wild game reserves of South Africa — snails, fish, even antelope, are showing signs of possible pharmaceutical contamination. For example, fish and prawns in China exposed to treated wastewater had shortened life spans, Pacific oysters off the coast of Singapore had inhibited growth, and in Norway, Atlantic salmon exposed to levels of estrogen similar to those found in the North Sea had severe reproductive problems.
More than 100 different pharmaceuticals have been detected in surface waters throughout the world.
"It's inescapable," said Sudeep Chandra, an assistant professor at University of Nevada, Reno who studies inland waters and aquatic life. "There's enough global information now to confirm these contaminants are affecting organisms and wildlife."
Scientists have been finding pharmaceuticals in hundreds of other public waterways across the nation and throughout the world — almost always without public fanfare, as documented in the AP investigation.
At the same time, scientists are looking for remedies. In Las Vegas, just off the Strip at the Desert Research Institute, microbial biologist Duane Moser optimistically held a tray of increasingly murky test tubes.
"We put a little bit of estrogen in here, and then we added a particular bacteria, and guess what? The bacteria are consuming the estrogen," he said. Someday, perhaps, scientists will be able to use these special bacteria to clean estrogen out of contaminated water.
"It's early, but it's promising," he said.