More rejection of natural selection in this scare about trout being denied their “pecan pie”?
The Minneapolis Star-Tribune reports,
A flying insect that thrives in midwinter might seem like a creature from a frightening fictional Minnesota.
But Diamesa mendotae, a cold-hardy but delicate insect also known as a midge, is very real and may provide a measure of how the state’s climate is warming, and what effect that might have.
Researchers from the University of Minnesota are working to understand more about the relationship between these unusual freeze-resistant insects and the fish that eat them in streams in the southeastern part of the state. The three-year project is primarily about brown trout, a popular target for anglers. “We’re thinking that a changing climate and increasing air temperatures will affect water temperatures, and that could reduce [fish] populations,” said entomology professor Len Ferrington, principal investigator on the project.
Midges are also at the heart of the study because of their unusual ability to thrive in the winter, when they serve as trout food. When most other insects are idling, with eggs and larvae hidden away from the cold, midges, armed with a sort of internal antifreeze, produce several generations of offspring. Stream anglers, skiers and others who might poke into the deeper recesses of southeastern Minnesota during winter see them flying in clouds above the water or speckling the streamside snow.
Jane Mazack, a graduate research assistant in the Water Resources Science program at the U, said Diamesa can remain active down to about 6 degrees below zero, which this winter would be the second-lowest temperature recorded in the Twin Cities.
The midges are also high in calories and nutrients — “like pecan pie” for trout, Ferrington said. But their cold-hardiness is balanced by an intolerance for warmth. An increase of as little as 1.8 degrees in the average water temperature in a stream could wipe out an entire winter reproductive cycle for them, Mazack said. That could mean less food for trout during winter, or at least less nutritious food in the form of other bugs…