Warming lakes put biodiversity at risk

A warming climate is warming the world’s lakes — and it could spell trouble for tropical fish, animals and tiny organisms.

In tropical climates like in Africa, warming is taking a toll on fish populations along with pollution and over fishing.

“It’s a kind of triple whammy,” said FIU Institute of Environment ecology professor Evelyn Gaiser, who was among the 37 contributors from 16 countries who participated in the study. “These organisms may not have the habitat to survive.” 

Previous studies focused on the surface temperature of lakes, but by examining 32 million water temperature readings at various depths, researchers were able to develop a more comprehensive and nuanced look at how climate change is affecting life in 139 freshwater lakes that represent 70 percent of the world’s surface freshwater.

Researchers determined fish and other organisms in temperate climates react to warming temperatures by changing the depth where they live. Because warmer temperatures aren’t warming lakes to one constantly higher temperature, these life forms might be able to find a comfortable — though not perfect — zone deeper below the surface where water temperatures rise less quickly.

That might not be an option in tropical climates where lakes showed they were more sensitive to temperature changes. Lakes in tropical climates tend to be shallower and fish and organisms might find that depths farther from the surface are less likely to be comfortable. They might not survive. And the people who rely on fish and them for food might need to find alternate sources of sustenance.

Gaiser, who is also a classically trained vocalist, had previously converted her temperature studies on Florida’s Lake Annie into music. In 2010, Lake Annie experienced a major cold snap that sounded like a big groan, Gaiser said.

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