Ecologists from Umeå University and the Norwegian University of
Science and Technology in Trondheim have studied fish
communities and fish habitat and reviewed the importance of
winter conditions for fish in streams and rivers in cold
regions. The findings are now being published in the journal
BioScience. It is well known that winter can be a stressful
season for plants and animals in streams and rivers. It is
reasonable to assume that more extreme weather conditions are
the most taxing, but the ecological significance of this is
poorly understood. The research team, headed by Professor
Christer Nilsson at Umeå University, describes how extreme
conditions – especially those associated with ice formation and
ice break-up – vary over time and affect both the non-living
river environment and its fish. For example, streams can fill up
with ice and kill all the fish that do not manage to flee to
backwaters or stretches with deep, quiet water that is not
filled with ice. Young fish are especially vulnerable. The r