OSLO
(Reuters) — 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, scientists said. The researchers in Germany and Canada said
that studies of the physical characteristics of animals showed that all have
widely differing "thermal windows" — a range of temperatures in which
they best feed, grow and reproduce.
That
meant that climate change would not affect all equally.
"Climate
change will favor species with wide thermal windows, short life spans, and a
large pool amongst its population," the journal said of the findings. Big
fish such as cod, which have narrow thermal windows, were moving north in the
Atlantic, for instance, partly because the food chain was disrupted by a shift
to smaller plankton, reducing the amount of prey on which large fish can feed.
A shift to smaller plankton meant that juvenile cod in the Atlantic had 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," Hans Poertner, of the Alfred Wegener Institute for
Polar and Marine Research, who was one of the authors, told Reuters. Knowledge
of the differences could help predict the 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 and thin species that grows up to about 500 grammes (1 lb), suffered more quickly than smaller specimens when summer temperatures rose above normal.
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