Tropical fish adapt to warmer waters

Some tropical fish can adapt quickly to living in warmer waters, and have a greater capacity to survive rising sea temperatures than previously thought.

Scientists at the government-backed Coral Reef Studies Centre of Excellence in Australia found that fish adjusted over several generations to a warmer habitat designed to reflect global warming. Researcher Jennifer Donelson said when damselfish were exposed to water temperatures 1.5 and 3 C higher than current levels, there was a marked decline in their aerobic capacity, affecting their ability to swim fast.

“The first generation really struggled with the increases in temperature,” she said.

“But with two generations maintained at these temperatures we saw that aerobic capacity was improved and increased to normal levels.”

Dr Donelson said the research showed some species could adjust faster than the rate of climate change – a damselfish reaches maturity within two years.

“The surprise was really how quickly it happened, that it only took two generations. I think everyone assumes that species will be able to adapt but how long it will actually take has been sort of unknown,” she said.

The study was designed to look at how fish would cope with the elevated sea temperatures expected by 2050 and 2100. Scientists used likely tropical ocean temperatures based on current trends in man-made carbon dioxide emissions.