Bluefin tuna born on opposite sides of the Atlantic spend their juvenile years together, before returning to natal waters in the Gulf of Mexico and the Mediterranean Sea to breed.

The findings could have implications for the management of what were once thought to be entirely distinct populations.

David Secor of the University of Maryland and colleagues looked at chemical signatures in the fish's inner ear to determine where each of the highly endangered fish came from.

Specifically, the team looked at a bone-like structure called the otolith, a calcium-carbonate deposit that is laid down after a fish hatches. These carry different concentrations of oxygen isotopes depending on whether the fish developed in cool Mediterranean waters - eastern bluefin - or warmer Gulf waters, which spawn western bluefin.

Eye colour and hair colour play a role in human partner choice, but visual stimuli can also determine mating preferences in the animal kingdom. In many species, the male's fortunes in the mating stakes are decided by a conspicuous breeding dress.

A study of brightly coloured fish has now demonstrated that this has less to do with aesthetics than with the sensitivity of female eyes, which varies as a result of adaptation to the environment. Females more attuned to blue will choose a metallic blue mate, while those better able to see red will prefer a bright red male. These mating preferences can be strong enough to drive the formation of new species - provided that habitat diversity is not reduced by human activities.

When a reactor in the Chernobyl nuclear power plant exploded in 1986 in what was then the Soviet republic of Ukraine, radioactive elements were released in the air and dispersed over the Soviet Union, Europe and even eastern portions of North America.

More than 20 years later, researchers from Case Western Reserve University traveled to Sweden and Poland to gain insight into the downward migration of Chernobyl-derived radionuclides in the soil. Among the team's findings was the fact that much more plutonium was found in the Swedish soil at a depth that corresponded with the nuclear explosion than that of Poland.

Radionuclides occur in soil both from natural processes and as fallout from nuclear testing.

Gerald Matisoff, chair of the department of geological sciences at Case Western Reserve University, Lauren Vitko, field assistant from Case Western Reserve, and others took soil samples in various locations in the two countries, measuring the presence and location of cesium (137Cs), plutonium (239, 240Pu), and lead (210Pbxs).

Thousands of feet below the bottom of the sea, off the shores of Santa Barbara, single-celled organisms are busy feasting on oil.

Until now, nobody knew how many oily compounds were being devoured by the microscopic creatures, but new research led by David Valentine of UC Santa Barbara and Chris Reddy of Woods Hole Oceanographic Institution in Massachusetts has shed new light on just how extensive their diet can be.

In a report to be published in the Oct. 1 edition of the journal Environmental Science & Technology, Valentine, Reddy, lead author George Wardlaw of UCSB, and three other co-authors detail how the microbes are dining on thousands of compounds that make up the oil seeping from the sea floor.

"It takes a special organism to live half a mile deep in the Earth and eat oil for a living," said Valentine, an associate professor of earth science at UCSB. "There's this incredibly complex diet for organisms down there eating the oil. It's like a buffet."

The latest findings of a University of Pittsburgh-based project to determine the environmental impact of routine pesticide use suggests that malathion - the most popular insecticide in the United States - can decimate tadpole populations by altering their food chain, according to research published in the Oct. 1 edition of Ecological Applications.

Gradual amounts of malathion that were too small to directly kill developing leopard frog tadpoles instead sparked a biological chain of events that deprived them of their primary food source. As a result, nearly half the tadpoles in the experiment did not reach maturity and would have died in nature.

The results build on a nine-year effort by study author Rick Relyea, an associate professor of biological sciences in Pitt's School of Arts and Sciences, to investigate whether there is a link between pesticides and the global decline in amphibians, which are considered an environmental indicator species because of their sensitivity to pollutants. Their deaths may foreshadow the poisoning of other, less environmentally sensitive species - including humans. Relyea published papers in 2005 in Ecological Applications suggesting that the popular weed-killer Roundup® is "extremely lethal" to amphibians in concentrations found in the environment.

Leading Florida-based scientific researchers released two new studies today, including a Florida State University report finding that climate change will cause significant impacts on Florida's coastlines and economy due to increased sea level rise.

A second study by researchers at Florida Atlantic University recommends that the state of Florida adopt a series of policy programs aimed at adapting to these large coastal and other impacts as a result of climate change. Key findings of the FAU report were included just this week by Florida Gov. Charlie Crist's Climate and Energy Action Team when it adopted the "Adaptation" section of its final report.

"The impacts of climate change on Florida's coasts and on our economy will be substantial, persistent and long-term, even under our conservative estimates," said Julie Harrington, director of the Center for Economic Forecasting and Analysis at FSU. "Should, as many models predict, sea level rise, and hurricane strength and other factors become more extreme, much greater economic impacts will occur along many parts of Florida's coast in this century."

The second new study, by researchers at FAU, focused on state adaptation policies needed as Florida faces the impacts of climate change.

"The goal of our study is to help the state of Florida adapt, in the most effective way possible, to climate change impacts that are now inevitable," said Jim Murley, director of Florida Atlantic University's Center for Urban and Environmental Solutions and leader of the study. "These approaches must be comprehensive and strategic, not piecemeal and episodic. Governor Crist and other leaders have rightly identified adapting to climate change as one of the state's greatest challenges -- we look forward to working with the state to protect our people, natural splendor, and economic livelihood. There is real work to be done."

Three more bodies were discovered over the weekend in areas of Texas ravaged by Hurricane Ike, increasing the storm's toll to 67 deaths nationally.

Gail Ettenger made her last phone call at 10:10 p.m. She was trapped in her Bolivar Peninsula bungalow with her Great Dane, Reba. A drowning cat cried outside. Her Jeep bobbed in the seawater surging around her home.

Black bears that live around urban areas weigh more, get pregnant at a younger age, and are more likely to die violent deaths, according to a study by the Wildlife Conservation Society (WCS).

The study, published in the Fall 2008 issue of the journal Human-Wildlife Conflicts, tracked 12 bears over a 10-year period living in urban areas around Lake Tahoe, Nevada and compared them to 10 "wildland" bears that lived in outlying wild areas. The authors found that bears in urbanized areas weighed an average of 30 percent more than bears in wild areas due to a diet heavily supplemented by garbage.

The authors believe that because the bears weigh more they are giving birth at an earlier age - on average when they are between 4-5 years old, as compared to 7-8 years for bears in wild areas. Some urban bears even reproduced as early as 2-3 years of age around Lake Tahoe.

Urban bears also tend to die much younger due mostly to collisions with vehicles, according to the study. All 12 urban bears tracked by the researcher were dead by age 10 due to vehicle collisions, while six of the wildland bears still survived. Bear cubs in urban areas also had dramatically higher mortality rates due mainly to vehicle collisions.

Cancun, Mexico - Dainty blue fish dart around coral shaped like moose antlers near the Mexican resort of Cancun, but sickly brown spots are appearing where pollution threatens one of the world's largest reefs.

Parts of the reef, nestled in turquoise waters, have died and algae -- which feed on sewage residues flowing out of the fast-growing resort city -- has taken over.

Coral reefs like Chitales, near the northern tip of a Caribbean reef chain stretching from Mexico to Honduras, are dying around the world as people and cities put more stress on the environment.

Climate change alone could trigger a global coral die-off by 2100 because carbon emissions warm oceans and make them more acidic, according to a study published in December.

But local environmental problems like sewage, farm runoff and overfishing could kill off much of the world's reefs decades before global warming does, said Roberto Iglesias, a biologist from UNAM university's marine sciences station near Cancun.

"The net effect of pollution is as bad or maybe worse than the effects of global warming," said Iglesias, a co-author of the study in the journal Science on how climate change affects reefs.

Human waste like that from Cancun's hotels and night spots aggravates threats to coral worldwide like overzealous fishing which hurts stocks of fish that eat reef-damaging algae.