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Top big-lake researchers converge on Duluth

Giant leaping carp are heading toward the Great Lakes. Quagga mussels have overtaken lakes Huron and Michigan. Lake Superior is warming faster than nearby areas on land. What's next? The myriad issues facing the world's biggest lakes -- from Baik...

Research project
Stephanie Guildford, an aquatic ecologist at the University of Minnesota Duluth's Large Lakes Observatory, watches as graduate student Rozhan Zakaria prepares a device to measure algae and phosphorus in Lake Superior. The researchers, who are studying the vertical movement of critters in the lake, were aboard UMD's Blue Heron research boat. Guildford is among many local researchers presenting her findings at this week's International Conference on Great Lakes Research in Duluth. (Photo courtesy of UMD)

Giant leaping carp are heading toward the Great Lakes. Quagga mussels have

overtaken lakes Huron and Michigan. Lake Superior is warming faster than nearby areas on land.

What's next?

The myriad issues facing the world's biggest lakes -- from Baikal in Russia, to Victoria in Africa, to the Great Lakes here at home -- will be the topic this week at the 54th International Conference on Great Lakes Research. The event will draw more than 600 scientists from around the world to the Duluth Entertainment Convention Center.

The event, for the first time held in Duluth, will include dozens of newly completed research projects presented for the first time.

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"This is our opportunity to compare notes and learn from each other," said

Randall Hicks, conference organizer, UMD professor and an expert in the field of determining the origin of bacteria in fresh water.

Featured presenters include Marianne Moore, aquatic ecologist from Wellesley College, who co-leads a team of Russian and American scientists studying 60 years of data from Lake Baikal -- the oldest, deepest, and most ecologically diverse lake in the world.

Sally MacIntyre, oceanographer from the University of California-Santa Barbara, will talk about climate-related changes in Africa's biggest lakes.

John Goss, the Obama administration's Asian carp czar, will talk about his team of federal, state and local agencies working together to prevent Asian carp from establishing populations in the Great Lakes.

There's no shortage of local experts who will present their findings as well.

Anett Trebitz, an ecologist at the Environmental Protection Agency's Duluth laboratory, is working hard on the "what's next?" question. She and her colleagues are conducting trials in the Duluth-Superior harbor to figure out ways to detect small numbers of invasive species before they become so abundant that they cause problems.

So, how many critters does it take to start an invasion? UMD researcher Don Branstrator, a leading expert on spiny water fleas, is studying the degree of perfection needed in efforts to kill invasive species in ballast water. If it's impossible to kill 100 percent of every tiny, invading creature, then what percent must be killed to prevent a new population from taking hold?

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And while much of the event will focus on emerging ecological problems in many of the world's largest lakes, several Twin Ports researchers will talk about ongoing improvements to Lake Superior's deepwater ecosystem. Those researchers say the big lake is doing so well it may become a model for restoration of other big lakes that have lost their natural systems.

As invading sea lamprey populations have been held in check over the last 50 years, thanks to chemical treatment of their spawning rivers, native lake trout are rebounding. So are ciscoes, commonly called herring.

The recovery of those bigger fish at the top of the food chain is now known to be part of a renewal of what scientists are calling the Lake Superior "nutrient elevator."

It's a phenomenon well-studied in fertile oceans but which few people understood in Lake Superior: Every night at dusk a potpourri of species -- from tiny shrimplike critters to fat lake trout -- swim toward the surface from 150 yards or more below.

"It's as if they're working night shift on the 35th floor of a high-rise," said Tom Hrabik, UMD researcher. "Hundreds of tons of fish and zooplankton make this huge vertical migration every day" through the summer.

At dawn, they ride the elevator back down. But they leave behind waste, namely phosphorous, near the surface. And that little bit of phosphorous is enough to spur the growth of phytoplankton, which make up the basis of the entire food web of the lake. Phytoplanktons are the food for another, slightly larger critter called the opossum shrimp (Mysis relicta), which in turn is food for small fish.

If any piece of the system is missing, the chain breaks down. Hrabik, along with EPA ecologists Jack Kelly and Mike Sierszen and UMD's Stephanie Guildford, are generating some new thoughts about how the native food webs of all Great Lakes functioned before they were upset by humans and foreign species.

"We're hypothesizing that the lake's whole food web may be dependant on this vertical migration. And that, because we have a healthy lake now, this may have been how the lake functioned for centuries before humans," Guildford said. "It's still a very cold, fragile, infertile lake. But because of this movement, the system works. And this may be the model for other lakes on what a healthy system should like."

Related Topics: ENVIRONMENTLAKE SUPERIOR
John Myers reports on the outdoors, natural resources and the environment for the Duluth News Tribune. You can reach him at jmyers@duluthnews.com.
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