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Watching our lakes

Limnologist Reavie may be based in Ely, but his research is wide-ranging

Terry Jackson
Posted 2/26/13

ELY- Nestled in a corner of the basement at Vermilion Community College in Ely is a small laboratory with a global reputation.  Dr. Euan Reavie is director of the Ely Field Station for the Center …

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Watching our lakes

Limnologist Reavie may be based in Ely, but his research is wide-ranging


ELY- Nestled in a corner of the basement at Vermilion Community College in Ely is a small laboratory with a global reputation.  Dr. Euan Reavie is director of the Ely Field Station for the Center for Water and Environment, part of the University of Minnesota-Duluth’s Natural Resources Research Institute.

While his laboratory is at the end of the road, Reavie is internationally known as an expert in paleolimnology, a study of the histories of inland waters and specifically the changes associated with events such as climate change, pollution and other human impacts. And his research is wide-ranging, starting as close to home as the White Iron chain of lakes and extending all the way to Lake Michigan.

Reavie obtained his doctorate degree in biology from Queens University in Kingston, Ontario, Canada after completing his dissertation on the St. Lawrence River.  “The purpose was to describe the human history of the river in terms of its ecology,” said Reavie.  The study resulted in the first report of its kind on rivers, showing both periods of degradation and remediation.  Reavie began research of the Great Lakes during postdoctoral studies at the University of Toronto.     

As a paleolimnologist, Reavie spends a lot of time looking at different forms of algae, particularly diatoms, through a microscope.  “The algae, being at the bottom of the food chain, are the first thing to respond to environmental changes like pollution or increases in turbidity, erosion or climate shifts,” said Reavie.   

Diatoms are a kind of algae that are used extensively as indicators of water quality. “Diatoms remain preserved in sediment, so they provide excellent opportunities to reconstruct historical information of a site,” said Reavie, “and we are able to determine water quality conditions of 20, 50, 100 or 1,000 years ago based on the species of diatoms found buried in lake bottoms.”  

WICOL study

Such changes in the makeup of diatom species may give Reavie and some Ely area residents greater insights into the effects of human activity on the White Iron chain, which Reavie is currently studying with help from the Minnesota Legacy Fund as well as private donations. Unlike most other lake studies, which are typically driven by specific problems, the WICOL study is more of an open-ended exploratory study providing background information on Garden, White Iron, Fall, Farm and Birch lakes.  

“The major thing we want to get from the WICOL study is to determine the sensitivity of these lakes to human activities,” said Reavie.  Analysis of the core sediments collected in each lake will provide information on how much change has taken place in the past 150 years due to human intervention. “Typically a study such as this doesn’t occur until a serious problem has been recognized, but these are by no means heavily-impacted lakes,” said Reavie.  

“We are likely to see changes due to logging, whether that had a persistent or very short term impact,” said Reavie.  More recent changes will also be evaluated, including changes due to nutrient inputs, invasive species, increased erosion, climate changes and human development.  

Border waters

While the White Iron chain lies close to the headwaters of the Hudson Bay drainage system, Reavie is also examining changes occurring a bit downstream. The international waters of the Rainy River and Lake of the Woods provide some of the best walleye fishing in the world and border communities rely heavily on the fishing industry to support their economy. 

“We are seeing massive blue-green algal blooms in the lake and that is never a good thing, said Reavie.   ‘It results in anoxia, the depletion of oxygen in the lake.”  Occasional algae blooms have occurred in the past, but in the last few years they have become much larger blooms that are visible from space.  

Algal blooms develop during the warmer months of the year when the water temperature is higher and there is increased light.  The longer ice-out period increases the potential for larger blooms.

“We are also seeing toxic algae, especially in more stagnant water bodies in Minnesota,” says Reavie, “and there have been reported pet deaths from dogs drinking the water.”  This has become a concern for resorts.  

Reavie will be presenting results from sediment cores he has analyzed at the Lake of the Woods Water Quality Forum in March.  

Great Lakes research

Of all the lake systems studied by Reavie, the Great Lakes have experienced the most significant impacts from human activities.

“We have seen dramatic changes in the Great Lakes in the past ten years,” said Reavie.  He attributes much of the change to invasive species being introduced to the Great Lakes by ocean-going ships when they release their ballast water at a port when taking on cargo.  “It is this ballast water being discharged into the Great Lakes that has been responsible for the introduction of many invasive species that have caused environmental and economic damage,” said Reavie. “We are now much better educated on the causes, but are still dealing with the legacy of problem species introduced years ago.”

The impact on Lake Michigan by the zebra and quagga mussels is a compelling example of the devastation caused by invasive species.  “The invasion of the quagga mussel, which followed the zebra mussel, has completely coated the entire basin of Lake Michigan,” said Reavie.  “We cannot collect a sediment sample anywhere in Lake Michigan without pulling up several kilograms of quaggas.  They are everywhere, feeding on tiny organisms that would normally feed other species, and they deposit their feces on the lake bottom preventing the recycling of nutrients in the system.”   

Reavie anticipated by now the quagga mussel would have extirpated itself in the lake as the zebra mussel did.  “I expect the quagga mussel will crash at some point and the entire lake system will go into flux.  We may see new species fill the open niche, and we may see occasional years of increased mussel abundance. It is possible we could also see large algal blooms because the mussels are suddenly removed from the phosphorus cycle.” 

Scientists began seeing a dramatic decline in algae about ten years ago after the quagga mussel invaded Lake Michigan.  “They compete for the food that small fish and invertebrates normally would be eating, so it threatens the pelagic (open water) fishing industry,” says Reavie.  The algae and invertebrates are food organisms and their disappearance is of significant concern to Great Lakes fisheries, which are already experiencing a decline in prey fish like alewife and game fish, including whitefish.  

Lake Superior has not been invaded by zebra and quagga mussels to the extent of other Great Lakes such as Michigan and Huron.  “We do see quagga mussels around Duluth, but there may not be enough food for them to get established in the deeper water,” said Reavie, “and Superior is physically quite different from the other Great Lakes.”  

“What we are seeing in Superior is a persistent change in species assemblage in the open water, and it appears to be related to climate change,” said Reavie.  

The Lake Superior summer water temperatures are increasing more rapidly than regional air temperatures.  According to a study by Jay Austin and Steven Colman of the Large Lakes Observatory, the surface water temperatures have increased approximately 2.5 degrees C over the interval 1979 - 2006, which is significantly in excess of regional atmospheric warming.   

Other climatic changes for the Great Lakes region include a shorter winter, warmer annual average air temperatures, more frequent extreme heat events and heavier precipitation events, both rain and snow, along with strong winds becoming more common.

Reavie is observing the effects of these changes in Lake Superior.  He said shorter winters also means less ice cover on the big lake, and that promotes faster warming of lake water. “Each year the lake gets warmer, and this is having an effect on the biology,” said Reavie. 

“Greater shifts in temperature gradients and more wind are creating a much thicker epilimnion,” says Reavie.  The epilimnion is a fresh water zone of relatively warm water in which mixing occurs as a result of wind action and convection currents.  This changing physical condition of the open water in the lake appears to be encouraging a new dominant group of diatoms named Cyclotella.  Reavie said every diatom or algae species has a very specific environmental preference related to a specific physical condition in the lake.  

Every such change, says Reavie, ripples through the food web, exacerbating the effects.

“There is no doubt there is a rapid change taking place in the lake and there is little doubt it is related to climate,” said Reavie. New data clearly show the epilimnion is also getting thicker in surrounding lakes, including an inland lake on Isle Royale. “These are lakes that have not been impacted by multiple stressors like Lake Superior and the actual climate effect can be isolated,” said Reavie. 

“I think we eventually will see some things occur quite dramatically,” said Reavie.  “If fish species start to change, it would be devastating for the Great Lakes.  Just having unpredictability in the biodiversity of the lake systems in combination with invasive species, climate shifts and other problems are causes for concern.”

Not all of the results from the Great Lakes are gloomy.  Reavie and his research team recently completed a paleolimnology assessment of Lake Superior.  Diatom records in the sediment provide clear evidence that, despite pollution impacts in the mid-20th century, significant improvement occurred in the lake’s water quality due to remediation laid out in the Clean Water Act.  “The size of these lakes is daunting, but it is great to see that we can make a real difference on such a large scale.”

The future

Reavie is also playing an important role in preventing invasive species from entering the Great Lakes from foreign ships. His goal is to evaluate whether newly-developed treatment systems are capable of killing everything in the ballast water, thereby making it safe to release the water into the Great Lakes.  

He is working closely with the Great Ships Initiative (GSI), a cooperative effort between the Great Lakes maritime industry, federal agencies, non-governmental organizations and academia to accelerate the development and installation of shipboard technology to prevent the introduction and spread of aquatic invasive species into the Great Lakes.  

The GSI onshore facility is at an abandoned ore dock in Superior, Wis.  The facility allows for testing and analysis of potential ballast water treatment technologies under controlled conditions that closely simulate ship operations.  “We are now testing systems that are actually installed on ships, and hopefully will validate some systems very soon,” said Reavie. 

Highlighting the global importance of this work, next week Reavie will be attending a workshop in Holland, at the Northern Netherlands Institute for Sea Research, which has a marine ballast water test facility.  The workshop is focused on finding the best way to analyze for tiny organisms in ballast tanks.  “We need something portable and user-friendly that can be operational on ships, because microscopes, my usual tool of choice, are not logistically feasible,” said Reavie.  Vendors will attend the workshop to demonstrate the latest equipment available.

Whether Reavie is writing a paper for publication, sharing scientific data at workshops with other scientists or analyzing samples through a microscope, he has a passion to know what is going on and an ability to recognize environmental changes.  The results of his work will truly make a difference in how we live today and how future generations can adapt to our changing environment.