Study finds weedkiller causes frog mutations
SAN JOSE, Calif. — Male frogs are turning into hermaphrodites in ponds and ditches polluted with atrazine, the most widely used agricultural weedkiller in the United States, scientists at the University of California-Berkeley reported Thursday in the journal Nature.
Researchers said the new study could help explain why frogs are in decline. Worldwide, 58 amphibian species have gone missing or extinct over the past two decades; an additional 91 are
critically endangered.
A report last spring by scientists at Pennsylvania State University said pesticide exposure appears to make frogs more vulnerable to parasitic worms that cause deformed limbs.
But researchers cautioned that other groups must duplicate the Berkeley work before the results can be considered definitive.
In the United States, atrazine is used mostly on corn and sorghum crops. It’s the most commonly detected pesticide in ground and surface water. The Environmental Protection Agency allows up to 3 parts per billion of the chemical in drinking water; it is now drawing up standards for levels of atrazine in surface water.
— Glennda ÏChui, Knight
Ridder Newspapers (KRT)
More plant species face extinction than thought
ST. LOUIS — More of the world’s plant species are threatened with extinction than previously believed, new research shows.
A study co-authored by Peter M. Jorgensen, a biologist at the Missouri Botanical Garden, suggests that between 22 percent and 47 percent of plant species worldwide are threatened.
Scientists had previously considered 13 percent of the world’s plant species threatened.
But that figure does not include a majority of countries in tropical regions, where most of the world’s species grow, Jorgensen said.
In the report, published Friday in the journal Science, Jorgensen and Nigel C.A. Pitman of Duke University found that 83 percent of Ecuador’s more than 4,000 native plants were threatened with extinction.
Based on the Ecuadoran model, the researchers were able to estimate missing data on native species in other tropical countries.
Because there is debate about the total number of world plant species, the researchers made separate calculations on two recent estimates of the total species: 310,000 and 422,000.
“We’re probably going to lose things that haven’t even been named and for which we have no idea what their utility for mankind might be,” said George Schatz, a botanist at the Missouri Botanical Garden. Plants are “doing all kinds of things for us. They’re trapping carbon dioxide and slowing global warming. They’re cleaning water. Plants are the basis of all life.”
Scientists say the No. 1 reason so many plant species are threatened with extinction is human destruction of their habitats.
“We need to have a good understanding about the species we have and the habitats we depend on,” said Kathryn Kennedy, a botanist at the Center for Plant Conservation at the Missouri Botanical Garden.
“(We need) an integrated approach to make man’s activities fit in that area in a sustainable way,” she said. “If we can do that, we’ll be protecting ourselves and the sustainability of our economy at the same time.”
— Jodi Genshaft, St. Louis Post-Dispatch (KRT)
