Millions Of Fish, Other Animals Die In Unprecedented Bolivian Cold Wave Lasting Most Of July - AFP

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Millions of aquatic animals in land-locked Bolivia's river systems have perished in unusually cold weather during the ongoing winter. The casualties include at least 6 million fish, thousands of alligators, turtles and river dolphins, scientific reports cited by Nature News said.

Losses of penguins were reported in Brazil and cattle deaths, affected by a cold snap from the Antarctic, hit farmers in Paraguay. The scientists' version of how the aquatic animals were decimated was hotly contested by visitors to Nature News Web site, while official Bolivian reports on the aquatic deaths were still awaited.

Bolivia is no stranger to extreme weather conditions as its geography interacts with humid tropical conditions but the aquatic deaths took scientists by surprise. Tens of thousands of Bolivians who depend on the river resources face a bleak future as officials try to work out how to deal with a developing ecological crisis and its impact on the communities and national economy.

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The trouble began after cold Antarctic air settled over the southern cone of South America for most of July. Water temperature in Bolivian rivers, normally about 59 degrees Fahrenheit, dropped to about 39 degrees Fahrenheit and was matched by the air temperature -- coldest since 36.5 degrees recorded in 1955. Other experts cited by Nature News said shock caused by extreme cold could cause the mass deaths among fish. "When fish die, it's usually not a single stressor, but multiple stressors interacting," said Steven Cooke, an aquatic ecologist at Carleton University in Ottawa. "So, if cold shock or cooler temperatures are being implicated in mortality, there's probably something else going on as well."

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http://www.terradaily.com/reports/Cold_snap_decimates_Amazon_aquatic_life_999.html