Absolutely swimming in bacteria.

Absolutely swimming in bacteria

With all its power and immensity, the ocean has been regarded as a wonderful dump site for human wastes. The wastes are treated before they reach the ocean, after all; and the idea is that any pathogens that survive are doomed in the vast and inhospitable sea. But according to an ongoing study developed for the Office of Technology Assessment (OTA), bacteria may survive quite nicely. They may be swimming alongside you the next time you take a dip in coastal waters.

Previous studies have concluded that seawater is deadly to bacteria, because after exposures as brief as a few hours they won't grow in normally supportive media. But according to Jay Grimes of the University of Maryland in College Park, a more sensitive laboratory technique now shows that some bacterial survivors have merely become dormant.

Grimes and his colleagues collected samples of coastal waters and incubated them with a food source and an antibiotic. Since the antibiotic prevented any bacteria surviving in the samples from dividing, bacteria that ate even small amounts were marked by their aberrant size, even if they were so quiescent as to appear dead. Grimes found that several species of human pathogens--including bacteria that cause cholera and dysentery--can survive for days in seawater. "And when we recover them, they're still capable of causing disease in experimental animals,' he says, adding that he believes the bacteria would have the same capability in humans. The bacteria return to normal levels of activity after passing through the experimental animals.

"It's of concern because the [sewage] treatment doesn't kill all the pathogens,' Grimes says. "We're slowly but surely building up a reservoir of these pathogens in coastal waters.'