"People tend to think of the lake as sort of there all the time," John Magnuson says of Lake Mendota. "One of the things I want to talk about is the time scales at which the lake changes, from seconds to thousands of years."
An authority on the long-term ecology of northern temperate lakes, the emeritus UW limnology professor has spent much of his career studying Lake Mendota - contributing to a body of knowledge that, since the late 19th century, has made it one of the world's most scrutinized and studied lakes. Around the clock and across the decades, he explains, it undergoes constant change on scales ranging from tiny to vast and from subtle to obvious.
Magnuson will present "A Changing Lake Mendota: Past, Present and Possible Futures," during the annual meeting of the Friends of the Lakeshore Nature Preserve. Scheduled for 7 p.m. Tuesday, April 10, at the UW Arboretum Visitor Center, the forum is an apt setting for the talk. The UW Lakeshore Nature Preserve helps to protect Lake Mendota, while its own lakeshore and the preserve itself are defined and affected by the lake.
"I think the lake is a bigger part of the lakeshore nature preserve than most people realize," says Magnuson, who hopes his perspective will help people view the preserve from offshore. Understanding the lake, he contends, is a prerequisite to knowing the preserve.
Any chance to hear Magnuson talk about Lake Mendota is an opportunity to understand it better. The recipient of a lifetime achievement award from the American Society of Limnology and Oceanography, the former director of the UW Center for Limnology continues to research topics in climate change and the ecology of fisheries. He sits on the Dane County Lakes and Watershed Commission, and is a nominee for election to the Friends of the Lakeshore Nature Preserve board.
On Tuesday, he intends to address a changing Lake Mendota in the context of its natural history - beginning with the geology of its formation, proceeding to the present and illustrating his presentation with examples of change that anyone can see.
He also anticipates talking about the feedback loop encompassing the human and lake environments. "People are starting to change their behaviors," he allows, "but these things don't happen fast. People need to have a more realistic view of that feedback loop."
When you know as much about Lake Mendota as Magnuson does, there are so many time scales you might discuss - such as the way wind can induce "a very strong wave dynamic with a very high amplitude. I'll try to use examples like that to illustrate the dynamics for what kinds of changes can happen day to night."
Then there is the subject of ice cover as a "miner's canary for global warming," he says. "If I get a chance, I'll also talk about how it's better to think ahead and prevent than wait and react. Working with the lake in this community is a continuous process. It's not a passive process. It takes patience."
Turning toward the future, Magnuson is not sure he will forecast any formalized scenarios for Lake Mendota. Threats to the lake posed by such exotic species as zebra mussels and Asian carp are well understood. So are the means to prevent their introduction. Even if the community acknowledges that it will cost more to fix such problems than to prevent them from happening in the first place, it remains an open question whether we will muster the social will to invest in the massive, even draconian efforts that would be required to protect Lake Mendota.
"I'm not going to talk so much about how bad things are or how bad things could get," Magnuson cautions, though "it's uninformed to assume Lake Mendota will stay the same." There are opportunities now, he says, to shift the way we think about such threats from cleanup mode to prevention mode. Those opportunities vanish once an exotic species infestation occurs.
"It's hard to get people to think ahead like that," he acknowledges. Still, "I wouldn't be inclined to be cynical. We're a pretty smart species, and this is a fairly progressive community."
The city, he points out, is ahead of the game in preserving its lakeshore, if not in allowing its shoreline trees to fall into the water and remain there as coarse woody habitat favorable to the lake's fishery.
"But I'm not going to talk about all the Bad News Bears," Magnuson emphasizes. "I'm not going to moralize. I'm going to talk about the scales of history."