What do higher temperatures mean for the lakes inhabitants?
"That's sort of the $64,000 question for the lake," Austin said. "How does this trickle down for the ecology and the fisheries in the lake? I don't think any of us have a really good feel for how different things are going to be."
"Fish have a specific range of temperatures in which they like to spawn," Austin said. "It may be that for some fish this very warm year is going to be great for them, but for others, like trout which are a very cold-adapted fish, it's not going to be great."
Fish migrations may change, because fish follow temperature boundaries, agreed Randall Hicks, an aquatic microbiologist, also of the University of Minnesota, Duluth, but not a part of Austin's work.
"Temperature is only one of the factors," Hicks said, speaking of the lake's smallest inhabitants. "Microorganisms grow much faster in warming temperatures, but the lake has relatively few nutrients, so there is a limit to how much they can grow."
Changes in microorganism populations can cascade through the ecosystem, since they form the base of the food chain. Blooms of microorganisms can deplete the oxygen in water, killing or driving away other aquatic life. Lake Superior's characteristics make it unlikely to suffer such problems, even as it warms, Hicks said.