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Below the depths

By Alex Piazza
apiazza@umich.edu

Some people dip their toes in Lake Superior to cool off on hot summer days.

Others stock their tackle boxes and head out to Lake Michigan to reel in salmon.

And a handful board freighters to transport raw materials along Lake Huron.

The Great Lakes are considered the most precious natural resource in the Midwest.

“What we have in the Great Lakes is a system that provides Michigan and the surrounding states and provinces economic and cultural vitality,” said Jennifer Read, director of the University of Michigan Water Center, part of the Graham Sustainability Institute that’s funded 37 research projects since its inception in 2012. “But these aren’t just a great state or regional asset—the Great Lakes are global in scale.”

"The integrity of the Great Lakes has been compromised over time, so we want to make sure that we do everything possible to restore, protect and maintain our most valuable resources."

Yet lakes Superior, Michigan, Huron, Erie and Ontario are routinely exposed to environmental influences that have potential to sour both the economy and public health.

Invasive species, such as zebra mussels, have reduced fish populations in Lake Huron. Toxic algal blooms in Lake Erie shut down the drinking water supply to more than 400,000 Toledo residents last summer. And erosion caused by rising water levels along stretches of Lake Michigan has forced some coastal community residents to vacate their homes.

About 40 miles separate Ann Arbor from its closest Great Lake—Lake Erie—but the work of about 70 U-M water researchers has a profound impact on the health and vitality of all five lakes.

“The integrity of the Great Lakes has been compromised over time, so we want to make sure that we do everything possible to restore, protect and maintain our most valuable resources,” Read said.

Unwelcome guests

Chalk it up as another day on the lake.

For the past 40 years, Tom Nalepa has conducted research on the Great Lakes. And for the past 27 years, he has focused his efforts on two notoriously unwelcome guests—zebra mussels and quagga mussels.

These mussels feed on algae, limiting a primary food source for many invertebrates, which fish eat. They also clog water intake structures and the infrastructure of power plants, leading to added costs. And for anyone whosever sliced their foot on a zebra mussel, they can be real nuisance.

“There are a lot of things happening in the Great Lakes these days—not all of which are good—that have been initiated by these mussels,” said Nalepa, a research scientist at U-M’s Water Center. “In fact, of the 180-some invasive species in the Great Lakes, there has never been any that has caused such widespread impact as these two mussel species.”

Nalepa has tracked invasive mussel populations in lakes Huron, Michigan and Ontario for decades, and his latest mission transpired last month aboard the Lake Guardian, a massive 180-foot research vessel owned by the U.S. Environmental Protection Agency. There, he and other scientists collected sediment samples from 160 sites across Lake Michigan.

“We used a grab scooper to basically take a bite out of the bottom of the lake,” he said.

"There are a lot of things happening in the Great Lakes these days—not all of which are good—that have been initiated by these mussels."

Back in the laboratory, all of the collected mussels will be counted and then compared to numbers from previous surveys.

Nalepa, who previously spent 35 years with the National Oceanic and Atmospheric Administration (NOAA), has conducted surveys at similar sites every five years for the past two decades to assess trends in invasive mussel populations.

Preliminary research shows that zebra mussels, which arrived in the late 1980s through ballast water from ships, are disappearing. Meanwhile, quagga mussels, which dwell in much deeper water, are increasing in some parts. Environmental changes below the surface likely spurred the population shift.

“That’s the big problem with invasive mussels,” he said. “There’s not a whole lot you can do to stop them from increasing. Once they’re settled, the scenario is going to play itself out. The key is to prevent invasive species from arriving here in the first place.”

Toxic menace

Toledo residents received the warning around 2 a.m. on August 2, 2014.

“Do not drink the water.”

Toxic algal blooms had developed along the western basin of Lake Erie and contaminated the drinking water supply of more than 400,000 residents.

Over the next 72 hours, Ohioans flocked to grocery stores for bottled water, as scientists and government leaders tried to track and understand how to better monitor and control the harmful green scum that, if consumed, can cause nausea, vomiting and liver damage.

Municipal managers eventually cleared the system and Toledo residents could safely drink water from their faucets. But the city again faces a similar dilemma, as predictions based on U-M research show an even-more severe algal bloom is set to develop in September along Lake Erie.

A primary culprit for these harmful algal blooms is fertilizer. Farmers spread fertilizer containing nitrogen and phosphorus across their fields to yield healthy crops.

But not all fertilizer is absorbed into the plants, and some of the nutrients can make their way into nearby waterways, particularly during heavy rain in the spring.

The Maumee River, which runs through Toledo, is surrounded by farms. So when nutrients enter the river, excess amounts of phosphorus in Lake Erie cause harmful algal blooms.

The toxic algae float on the surface, but strong winds and waves can push it downward into deep-water intakes serving treatment plants, said Don Scavia, Graham Professor of Sustainability at U-M whose research focuses on algal blooms.

Phosphorus-driven algae also cause problems in Lake Erie’s central basin. These excess algae eventually settle to the lake bottom and decompose, creating a “dead zone” in which oxygen levels are nearly depleted.

“Nothing can survive in these dead zones,” Scavia said. “It’s hard for people to appreciate dead zones because it’s simply a layer of cold water along the bottom of the lake, but its presence poses serious harm to fish. So toxic algae not only harm your drinking water—excess algae also can reduce the fish population in the Great Lakes. We can no longer cross our fingers and hope for the best. We need to look for ways to reduce nutrient runoff so we can protect the health and vitality of our lakes.”

Changing tide

The docks are noticeably shorter along the beaches of Lake Huron in Tawas City.

And boaters with skiers in tow can hug the shoreline a bit closer during afternoon cruises.

It’s all because the water levels along lakes Huron and Michigan are the highest on record since 1998, according to the NOAA Great Lakes Water Level Dashboard.

“We were experiencing historic lows just two years ago, but all that’s changed over the past 18 months,” said John Callewaert, Integrated Assessment director at the Graham Sustainability Institute.

Since September 2014, all five Great Lakes have been above their monthly average levels for the first time since the late 1990s.

But rising water levels aren’t always good. Consider the family who built their cottage along the shoreline. Coastal erosion and flooding caused by rising lake levels could result in serious property damage.

On the flip side, low lake levels also can pose problems, like interfering with commercial shipping operations, not to mention how it hinders recreational boating and tourism.

Shoreline communities across Michigan face a litany of challenges resulting solely from variable water levels, so researchers from 16 U.S. and Canadian universities, supported by grants from U-M, have identified solutions that will help residents and businesses cope with ongoing fluctuations in the Great Lakes.

“This is what the Great Lakes do—they go up, they go down,” Callewaert said. “We’re working to identify ways to live with a dynamic system.”

"This is what the Great Lakes do—they go up, they go down. We’re working to identify ways to live with a dynamic system."

U-M awarded $10,000 grants last year to seven research teams, so they could work with communities across the region, including Michigan. Their mission was to identify local problems that stem from water level fluctuations.

In November, some of those research teams will receive an additional $50,000 to embark on an 18-month integrated assessment in which they will identify and analyze practical, localized options to minimize negative impacts of Great Lakes water fluctuations, like improved shoreline planning.

“The purpose of this project is to equip communities with a robust set of strategies that allow them to adapt to water level changes, while protecting ecological integrity, economic stability and cultural values,” Callewaert said. “This research will then help community leaders decide how to best move forward.”

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