'Fish guts can tell which species will survive climate change'
Washington: Scientists have discovered that the gastrointestinal system of fish is much more sensitive to temperature changes than previously thought, a finding they say could help predict which species would survive climate change and which would not.
"Our work is largely about trying to identify the physiological bottlenecks, in other words which parts of the body will fail first -- whether the heart or the gut is the most sensitive part of the system," study researcher Albin Grans, of the University of Gothenburg, in Sweden, was quoted as saying by LiveScience.
The scientists, who studied gut functions of various fish species to better understand what will happen to different species when the climate changes, found that the gut was actually the most temperature-sensitive organ in many fishes.
Grans said: "When the temperature of the water rises, the fish's body temperature climbs, activity in the gut increases, and more energy is needed to stay healthy.
"Since changes in body temperature affect virtually all of a fish's organs, it's surprising that we know so little about how temperature changes impact on their physiology."
For their study, the researchers studied guts of sculpin, sturgeon and rainbow trout in sea and freshwater environments in Sweden, California and Greenland.
As fish don't produce their own body heat, their body temperature is the same as that of their surroundings. When the water temperature changes, so does the temperature of the fish. Some species may find it harder to absorb nutrients as water temperatures rise, while others could profit from the new climate, Grans said.
"If the water temperature in the Arctic rises further, some sedentary species, such as various types of sculpin, will probably struggle to maintain blood flow in the gut during the summer months, which will affect their health," he noted.
Other fish, such as those currently living at the lower extremes (the coldest environments they can survive) of their possible spatial distribution, could instead benefit from a slightly higher temperature. The effects of a rise in water temperature will therefore vary between species, and many of the changes are difficult to predict, Grans said.