A cat-eating lizard native to Africa is being targeted by Florida state wildlife officials who say the creatures, known as Nile monitors, could be dangerous to pets and people.

The Florida Fish and Wildlife Service said Friday it is "increasing efforts to locate and remove them," particularly along canals in Palm Beach County, north of Miami.

Inbreeding is generally considered dangerous, but for endangered mountain gorillas in central Africa the practice has helped them survive by reducing harmful genetic mutations, researchers said Thursday.

Habitat destruction and hunting have seriously cut down on the population of gorillas in the mountains of Rwanda, Uganda and the Democratic Republic of Congo. By 1981 there were just 253 left.

Ocean acidification was a key driver of the greatest mass extinction on Earth some 250 million years ago, scientists said Thursday.

The changes to the Earth's waters were caused by a rash of volcanic activity, wiping out more than 90 percent of life in the oceans and two-thirds of land animals, said the authors of the study in the journal Science.

Rescuers were forced to abandon efforts to save around 150 melon-headed whales that stranded on a beach in Japan on Friday, after frantically trying all day to save them.

As darkness fell, local officials in Hokota, about 100 kilometers (60 miles) northeast of Tokyo, said they had been able to save only three of the 149 animals that had beached and that the rescue effort had been called off.

North and South America joined together between 13 and 15 million years ago -- some 10 million years earlier than scientists previously thought, a new study said Thursday.

The two continents were once separated by a deep strait called the Central American Seaway that at some point morphed into a land bridge -- the Panama arc.

Fifteen Turkish ecological activists could face up to seven-and-a-half years in jail after prosecutors charged them with public order offences over protests against the construction of a mosque in Istanbul last year, judicial sources said Thursday.

The activists have been charged in the indictment by prosecutors with breaking the law on protests and throwing bottles and stones at the security forces.

Scientists are working to pinpoint the source of a giant mass of methane hanging over the southwestern U.S., which a study found to be the country's largest concentration of the greenhouse gas.

The report that revealed the methane hot spot over the Four Corners region — where Colorado, New Mexico, Utah and Arizona meet — was released last year.

Japan will promise to cut its greenhouse gas emissions by 20 percent from 2013 levels ahead of a global summit on climate change this year, a report said Thursday, despite uncertainty over post-Fukushima energy policy.

The government will likely announce the new target at the Group of Seven (G7) summit in June in Germany, the leading business daily Nikkei reported, citing unnamed government sources.

Vietnamese authorities are searching for a lead box containing hazardous radioactive material which has gone missing from a steel factory, an official said Wednesday.

The box of cobalt-60, which has a wide range of uses including for radiotherapy and in industry, has disappeared from the Vietnamese-owned Pomina steel mill in the south of the country.

Oil giant Shell filed a legal complaint Tuesday against Greenpeace protestors who have boarded an Arctic-bound oil rig in the middle of the Pacific Ocean, a spokeswoman said.

The six activists are camping out on the 38,000-ton Polar Pioneer platform, which they boarded 750 miles northwest of Hawaii using inflatable boats from the Greenpeace vessel "Esperanza."