EVEN when they tiptoe discreetly through the undergrowth, nature lovers and ecotourists may be having an unexpectedly damaging impact on wildlife. A study of protected Californian forest has shown that hiking, wildlife-watching and similar low-impact activities are linked to a sharp drop in numbers of carnivores such as bobcats and coyotes.

As athletes from around the world compete in the Beijing Olympics, many are on alert for respiratory problems caused by air pollution. They should also be concerned about its toxic effects on the heart and cardiovascular system, mounting research shows.

Rare trees in the Amazon basin are more likely to
go extinct than common species, according to scenarios based on neutral
theory.
Common tree species in the Amazon will survive even grim scenarios of deforestation and road-building, but rare trees could suffer extinction rates of up to 50 percent, predict Smithsonian scientists and colleagues in the Aug. 12 issue of the journal Proceedings of the National Academy of Science.

Seeing disease-fighting white blood cells vanish from the blood usually signals a weakened immune system.

Jeremy Jackson, Scripps Professor of Oceanography. Human activities are cumulatively driving the health of the world's oceans down a rapid spiral, and only prompt and wholesale changes will slow or perhaps ultimately reverse the catastrophic problems they are facing.

"Flesh-eating" or "Strep" bacteria are able to survive and spread in the body by degrading a key immune defense molecule, according to researchers at the University of California, San Diego, School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences. The finding, which could aid in development of new treatments for serious infections in human patients, will be reported in the August 14 issue of the journal Cell Host & Microbe.