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Fish fry.

[ILLUSTRATION OMITTED]

Fishermen wouldn't have much trouble catching their fill in this Brazilian lake. The only problem is, all of these fish are dead.

What has caused Rey Lake to become jam-packed with belly-up fish? In the Amazon region, where Brazil is situated, the sun shines a lot. This causes the water in lakes and rivers to evaporate, or change from liquid to a gaseous water vapor. Usually, lots of water evaporates each day, but at the same time, there is plenty of rain to replace it, so the lakes stay full. In recent years, however, the Amazon region has been experiencing severe drought conditions, says James Eisner, a geography professor at Florida State University. With less-than-normal rainfall, there is not enough precipitation to replace the evaporating water. Result: Rey Lake is drying up. After a while, what little water remains becomes too muddy for the fish to get the oxygen they need to survive. The dead fish die and float to the lake's surface.

According to Elsner, the lack of rain may be due to a shifting of wind patterns caused by the warming of waters in the northern Atlantic Ocean. Normally, north-blowing winds and south-blowing winds meet in an area called the intertropical convergence zone, or ITCZ. Where these winds join, they produce rain and create thunderstorms. This zone used to be located above Brazil. Now, the ITCZ has moved northward to the Caribbean Sea.

Global warming, or the increase in Earth's average temperature, may be to blame for the warmer waters, says Elsner. If that's the case, more droughts are likely in the future. But there could be other explanations too, he says. For instance, warmer waters could be a normal part of the thermohaline circulation cycle, or a period of 20 to 30 years in which the Atlantic Ocean naturally warms and cools. If that's the case, residents of the Amazon simply need to wait for the balance of rain and evaporation to be restored.

With two or three good rainy seasons, the fish could be swimming in Rey Lake again, says Eisner.
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Title Annotation:GROSS OUT
Author:Moser, Jennifer
Publication:Science World
Date:Jan 14, 2008
Words:347
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