London, Nov 1 : A new research has determined that climate change is likely to disrupt food chains by favoring animals with short lifespans over often bigger rivals that are worse at tolerating temperature swings.
According to a report in New Scientist, researchers in Germany and Canada said that animals have widely differing "thermal windows" - a range of temperatures in which they best feed, grow and reproduce.
That means that climate change will not affect all equally.
"Climate change will favour species with wide thermal windows, short lifespans and a large gene pool amongst its population," according to an article in the journal Science.
Big fish such as cod, which have narrow thermal windows, are moving north in the Atlantic, for instance, partly because the food chain has been disrupted by a shift to smaller plankton, reducing the amount of prey on which large fish can feed.
A shift to smaller plankton means that juvenile cod in the Atlantic have to use more energy to feed, slowing their growth.
Female cod tolerate only a narrow "thermal window" when they produce eggs, part of a strategy evolved to cut energy use.
The study focused on the oceans, but the scientists said the findings may also apply to land creatures.
"Each species covers a certain range. The ranges overlap, but their (thermal) windows are not the same," said Hans-Otto Portner of the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven, Germany, one of the authors.
Knowledge of such differences could help predict reactions to climate change, widely blamed on human emissions of greenhouse gases from burning fossil fuels.
In the German Wadden Sea, larger eelpout fish - a long, thin species that grows to about 500 grams - suffered more quickly than smaller fish when summer temperatures rose above normal.
"In the Japan Sea, different thermal windows between sardines and anchovies caused a regime shift to anchovies in the late 1990s," the researchers said.