NOAA Great Lakes Environmental Research Laboratory

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Underwater robots significantly advance our ability to study Lake Erie’s harmful algal blooms

Newly published research from the NOAA Great Lakes Environmental Research Laboratory (GLERL), the Cooperative Institute for Great Lakes Research (CIGLR), and partners reveals that using underwater robots could significantly advance scientists’ ability to study the harmful algal blooms (HABs) that appear in the Great Lakes and oceans every summer. You may remember reading about NOAA’s collaborative fieldwork in 2019 that used these robots to detect toxins in Lake Erie’s harmful algal bloom. Three years later, the findings from this pioneering research come bearing good news!

This autonomous underwater vehicle (AUV), known as “Makai,” visited the Great Lakes from the Monterey Bay Aquarium Research Institute (MBARI) to help scientists study Lake Erie’s harmful algal bloom. Credit: Steve Ruberg, NOAA GLERL

What are HABs, and how do we study them?

HABs occur when colonies of algae grow out of control and produce toxic or harmful effects on people, fish, shellfish, marine mammals and birds. Western Lake Erie in particular has been plagued by intensified HABs over the past decade. These blooms consist of cyanobacteria, or blue-green algae, which are capable of producing toxins that endanger human and animal health, compromise drinking water supplies, foul coastlines, and impact communities and businesses that depend on the lake. 

Harmful algal bloom in western Lake Erie in October, 2011. Credit: NOAA Great Lakes CoastWatch

The underwater robot used in this research project is known as a long-range autonomous underwater vehicle, or LRAUV. As the name suggests, the LRAUV is built to travel long distances beneath the water’s surface, collecting data for an extended period of time. LRAUVs are useful research tools, as they can collect high-quality data more efficiently and cost-effectively than scientists taking samples from a ship or along the shore. They can be deployed day and night in all weather conditions, and can provide more detailed information to researchers and drinking water managers than other monitoring methods.

For this project, NOAA and CIGLR teamed up with the Monterey Bay Aquarium Research Institute and university partners to equip an LRAUV with a 3rd Generation (3G) Environmental Sample Processor (ESP) — a mobile version of what has previously been known as NOAA’s “lab in a can.” The 3G ESP’s job is to measure microcystin, a potent liver toxin produced by the cyanobacteria that cause harmful algal blooms in the Great Lakes. In just a few hours, the 3G ESP can collect and analyze water samples from the bloom with the same methods that scientists use to analyze samples back at the lab. It does this with the use of ‘omics, a collective suite of technologies used to analyze biological molecules such as DNA, RNA, proteins, or metabolites. These technologies can be used to identify the algal species that produce HABs, understand their behavior, and predict shifts in their population structure.

NOAA and partners deployed the LRAUV-3G ESP in Lake Erie to autonomously measure microcystin, a potent liver toxin produced by the cyanobacteria that cause harmful algal blooms in the Great Lakes. Photo credit: NOAA

Did this robot step up to the challenge?

Before widely adopting the use of the LRAUV-3G ESP to study Lake Erie HABs, scientists had to ensure that the data these instruments collect is accurate and reliable. A main goal of the new publication was to assess how dependable the LRAUV-3G ESP’s data is compared to data that was collected and analyzed by humans.

The authors used a variety of parameters to assess the vehicle’s performance of ‘omics tests on samples it collected from the HAB. They ultimately found that the LRAUV-3G ESP successfully performed flexible, autonomous sampling across a wide range of HAB conditions, and the results indicated equivalency between autonomous and manual methods. In fact, no significant differences were found between LRAUV-3G ESP and manual sample collection and handling methods in the 12 parameters tested. In other words, this robot passed the test!

Left: Scientists retrieve the LRAUV-3G ESP from its mission to measure algal toxins in Lake Erie. Photo credit: NOAA AOML. Right: First author Paul Den Uyl (CIGLR) CIGLR retrieves 3G ESP filters for analysis of Lake Erie microbial community DNA. Photo Credit: Kelly Godwin.

One of the most exciting aspects of this research is that it shows that scientists can use an autonomous sampling platform to replicate traditional ship-based sampling, and they can do so in a particularly challenging environment (Lake Erie’s shallow western basin) where HABs are a serious health concern. Using this instrument in Lake Erie’s shallow waters presented another challenge for the scientists involved. In response to the lake’s challenges, researchers worked on the LRAUV’s buoyancy to ensure that the instrument didn’t drag across the ground. With this technology – sampling DNA and measuring toxins on an autonomous platform – NOAA and partners may be able to provide an early warning system for HABs in the future.

The 3rd Generation Environmental Sample Processor demonstrates engineering advancements from the first and second generation ESPs. Photo credit: NOAA GLERL.

Partners on this research came from far and wide to conduct this important research:

  • National Oceanic and Atmospheric Administration (NOAA)
    • NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML), Ocean Chemistry and Ecosystems Division
    • NOAA Great Lakes Environmental Research Laboratory
    • NOAA National Centers for Coastal Ocean Science (NCCOS)
    • NOAA Southwest Fisheries Science Center
  • Cooperative Institute for Great Lakes Research (CIGLR), University of Michigan
  • Northern Gulf Institute, Mississippi State University
  • Monterey Bay Aquarium Research Institute (MBARI)
  • Department of Earth and Environmental Sciences, University of Michigan

Explore more photos of this research on NOAA GLERL’s Flickr page.


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Lessons from Lake Huron: A look back at NOAA GLERL’s 2022 fieldwork for the Cooperative Science and Monitoring Initiative

Every summer, NOAA GLERL scientists travel far and wide across the Great Lakes region to study the biological, chemical, and physical properties of these amazing lakes. A portion of this fieldwork contributes to a larger project called the Cooperative Science and Monitoring Initiative – or CSMI – which helps us take a deeper dive into studying a different Great Lake each year. Instituted under the 2012 Great Lakes Water Quality Agreement, CSMI is a multi-agency, international effort to coordinate science and monitoring activities in one of the five Great Lakes each year to generate data and information for environmental management agencies.

MODIS satellite image of Lake Huron on May 18, 2021. Credit: NOAA Great Lakes CoastWatch Node.

Each Great Lake gets a “CSMI year” once every five years, and 2022 was Lake Huron’s turn to shine. Sitting right at the center of the Great Lakes region, Lake Huron is shared by the state of Michigan and the Canadian province of Ontario. It’s the second largest of the Great Lakes and ranks as the fourth largest lake in the world by surface area. Lake Huron provides economically and culturally important services, including a productive fishery, a source of clean drinking water, and natural beauty that supports a significant tourism industry. It’s also home to Thunder Bay National Marine Sanctuary, the first ever NOAA National Marine Sanctuary to be established in the Great Lakes.

GLERL’s fieldwork for this year’s Lake Huron CSMI efforts focused on benthic and spatial surveys in Thunder Bay and Saginaw Bay. Here’s a look back at some of the highlights!

GLERL scientists Ashley Elgin and Rachel Orzechowski rinse down sediments collected by a Ponar grab.

NOAA GLERL has been conducting benthic (lake bottom) research in the Great Lakes since 1980, during which time we have built an unparalleled record of the arrival and expansion of invasive zebra and quagga mussels. CSMI provides the perfect opportunity to expand on this knowledge. Surveying the lake bottom allows us to track the population dynamics of these mussels, follow their impacts on native species, and also monitor for any new invasive benthic species. 
GLERL scientist Paul Glyshaw collects Ponar samples onboard the Fisheries and Oceans Canada/Canadian Coast Guard vessel Limnos for mussel length-weight analysis.

In June, July, and August of this year, GLERL conducted surveys that will allow us to update the status of invasive dreissenid mussels and other benthos of Lake Huron. As an exciting bonus, our benthic surveys in Saginaw Bay and Thunder Bay even received dive support from Thunder Bay NMS to supplement the samples collected with Ponar grabs.

Thunder Bay NMS divers Stephanie Gandulla and John Bright support GLERL’s benthic survey on board the R/V 5503.
The large metal claw used for a Ponar grab is no match for a mussel-covered rock like this, which is why we need NOAA’s Thunder Bay NMS Divers to support the benthic survey.

In the truly collaborative fashion that CSMI is known for, GLERL scientists maximized time on these cruises by collecting samples for several federal and university collaborators in addition to conducting our mussel survey.  For example, mussels and sediments went to the U.S. Geological Survey for mercury analysis, and researchers from the University of Michigan will be looking for mussel environmental DNA in water samples.

This sediment sample from Saginaw Bay has many benthic inverts present, including dreissenid mussels, chironomids, water mites, amphipods, and a snail. 
Paul Glyshaw collects and filters Lake Huron water onboard the Fisheries and Oceans Canada/Canadian Coast Guard vessel Limnos to measure carbon content. This helps us address potential impacts of climate change on the lake, including acidification, changes to production, and altered biogeochemical processes.

Plus, GLERL also teamed up with the U.S. Environmental Protection Agency, Fisheries and Oceans Canada (DFO), and the Canadian Coast Guard in a whole lake-benthic survey, during which GLERL assessed mussel body condition, mussel reproduction, inorganic carbon measures, and collected water for eDNA across the lake. In true CSMI spirit, DFO stepped up and supported the benthic survey when the EPA R/V Lake Guardian became unavailable. 

Fisheries and Oceans Canada/Canadian Coast Guard vessel Limnos pulls into Port Huron for the Lake Huron Benthic survey.

In addition to surveying what’s happening on the lake floor, GLERL also conducted an intensive spatial survey through CSMI to study Lake Huron’s food web in the area between Thunder Bay and Saginaw Bay. With a special focus on studying the interactions between larval fish and plankton, one of the key instruments used was GLERL’s Plankton Survey System (PSS). This high-tech piece of equipment is a towed multi-sensor platform capable of measuring turbidity, chlorophyll a, photosynthetically active radiation (PAR), conductivity, temperature, and zooplankton spatial distributions.

GLERL scientists use the PSS on Lake Michigan in the mid 2000s.

The plots below show a nearshore to offshore view of Lake Huron’s biological data measured by the PSS, like water temperature, dissolved oxygen, and chlorophyll, and plankton distribution. Check out more PSS plots from this spatial survey here.

While the PSS instrument was collecting data below the waves, lots of mayflies were catching a ride on this research cruise!

Now that the fieldwork is complete, the next step for GLERL’s CSMI work is to process our samples and analyze our data to continue building our knowledge of Lake Huron. Stay tuned in 2023, when CSMI heads east to study Lake Ontario!

For more CSMI information, data, and findings, visit greatlakescsmi.org. Plus, check out this related CSMI project in which GLERL and CIGLR developed an Experimental Biophysical Modeling Forecast System for Lakes Michigan and Huron.


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New wave buoy will provide data to support wave and flood forecasting on Lake Champlain

The NOAA Great Lakes Environmental Research Laboratory (GLERL) and partners recently deployed a buoy in Lake Champlain that will measure the lake’s wave heights to assess the accuracy of a new experimental model for the lake. This is part of a five-year NOAA GLERL project that will improve public safety on Lake Champlain by contributing to flood preparedness and response around the shores of the lake. Wave conditions are critical to public safety both for recreational and commercial activities on the lake – such as for boats, harbors, and beaches – but also for predicting coastal flood impacts at the shoreline where waves can run up and significantly impact infrastructure.

Left: Newly deployed NOAA buoy in Lake Champlain. Credit: University of Vermont FEMC staff. Top right: NOAA GLERL partners at the University of Vermont’s Forest Ecosystem Monitoring Cooperative (FEMC) deployed the buoy on Lake Champlain in May 2021. Credit: University of Vermont FEMC staff. Bottom right: Sunset on Lake Champlain. Credit: Dan Titze, CIGLR.

The project is a major collaborative effort by bi-national, federal, and university partners of NOAA GLERL. Partners at the University of Vermont’s Forest Ecosystem Monitoring Cooperative (FEMC) deployed the seasonal buoy in May, and the Coastal Data Information Program (CDIP) at the University of San Diego Scripps Institute of Oceanography receives the data, manages its quality control, and posts it to NOAA’s National Data Buoy Center (NDBC) website. Researchers at the Cooperative Institute for Great Lakes Research (CIGLR) are currently leading the development of a wave model for Lake Champlain, which is providing experimental forecasts on the GLERL website.

The buoy is located in the middle of the lake near Schuyler Reef, where it will remain until late fall, and is collecting wave height observations that will be used to validate NOAA’s WAVEWATCH III model for Lake Champlain. The experimental model’s output data will be compared to the buoy’s observed data, which will help scientists assess how well the model performs.

Location of the new NOAA Lake Champlain wave buoy, depicted by a yellow diamond. Map credit: NOAA National Data Buoy Center.

The buoy’s environmental data can be found on the CDIP website, and on the buoy’s page on the NOAA NDBC website. The buoy and the experimental wave model will be a helpful new tool for the region’s National Weather Service Weather Forecast Office in Burlington, Vermont, which provides lake forecasts including wave data to mariners in the region.

In addition to regional weather forecasters and local mariners, this buoy’s data will also be useful to emergency managers in the counties and cities around Lake Champlain and the Richelieu River, as well as the NOAA National Centers for Environmental Prediction which will transition the WAVEWATCH III model to operations.

This project is funded by the International Joint Commission’s Lake Champlain-Richelieu River (LCRR) Study Board. The International Joint Commission (IJC) is a bi-national organization established by the governments of the United States and Canada under the Boundary Waters Treaty of 1909. It oversees activities affecting the extensive waters and waterways along the Canada–United States border. The IJC’s LCRR Study Board was created in 2016 to undertake a study of the causes, impacts, risks, and potential solutions to flooding in the LCRR basin.


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Five decades of Great Lakes ice cover data – and where to find it

Understanding the major effects of ice on the Great Lakes is crucial. Ice cover impacts a range of societal benefits provided by the lakes, from hydropower generation to commercial shipping to the fishing industry. The amount of ice cover varies from year to year, as well as how long it remains on the lakes. With almost five full decades of ice data to look at, GLERL scientists are observing long-term changes in ice cover as a result of climate change. Studying, monitoring, and predicting ice coverage on the Great Lakes plays an important role in determining climate patterns, lake water levels, water movement patterns, water temperature structure, and spring plankton blooms.

Maximum ice cover on the Great Lakes every year from 1973 to 2018. Credit: NOAA GLERL.

NOAA GLERL has been exploring the relationships between ice cover, lake thermal structure, and regional climate for over 30 years through the use of historical model simulations and observations of ice cover, surface water temperature, and other variables. Weekly ice cover imaging products produced by the Canadian Ice Service (CIS) started in 1973. Beginning in 1989, the U.S. National Ice Center (NIC) produced Great Lakes ice cover charts that combined both Canadian and U.S. satellite imagery. Today, these products are downloaded and processed at GLERL by our CoastWatch program, a nationwide NOAA program within which GLERL functions as the Great Lakes regional node. In this capacity, GLERL uses near real-time satellite data to produce and deliver products that support environmental decision-making and ongoing research. While the Great Lakes CoastWatch Program is a great resource for near real-time ice cover data, historical data is just as important – and that’s where GLERL’s Great Lakes Ice Cover Database comes in. Originally archived by GLERL through the National Snow & Ice Data Center, the Great Lakes Ice Cover Database houses data that dates back to 1973 and continues to be updated daily during the ice season every year.

Ice caves on Lake Michigan’s Glen Haven beach in 2005. Credit: National Parks Service.

Even though the CIS and NIC are the ones who actually collect Great Lakes ice cover data, GLERL plays the important role of re-processing this ice data into more accessible file formats, making it readily usable to anyone who needs it. Agencies and organizations that have used ice cover data from GLERL in the past include the NASA Earth Observatory, U.S. Army Corps of Engineers, U.S. Coast Guard, and National Geographic. Types of data requested might include historic minimum and maximum ice coverage for certain regions or lakes, or dates of the first and last ice cover in a region from year to year. This information can be helpful for managers in industries like energy production and commercial shipping.

This graph shows annual maximum ice coverage on the Great Lakes every year from 1973 to 2020. The red dashed line marks the long-term average maximum ice cover of 53.3%. Credit: NOAA GLERL.

GLERL scientists can also use this historic ice cover data to analyze how current ice cover conditions compare with previous years. For example, here’s how the ice cover during January 2021 stacks up against data for past Januarys:

  • Lake Michigan and the five-lake average had their second lowest January ice cover (with January 2002 being the first lowest).
  • The other lakes are all in the top five lowest ice cover for the month of January.
  • Six out of ten of the Januarys with the lowest ice cover have occurred during the last decade for the five-lake average (though 2014 was fourth highest January ice cover).
This graph shows average Great Lakes ice cover for the month of January every year from 1973 to 2021, organized by lowest ice cover (far left) to highest ice cover (far right). Credit: NOAA GLERL.

GLERL is also working to make this data more user-friendly for anyone looking to utilize it. This recent paper from GLERL and the Cooperative Institute for Great Lakes Research (CIGLR) describes the scientists’ efforts to standardize two existing formats of historic ice cover data. The authors explain that “technology has improved and the needs of users have evolved, so Great Lakes ice cover datasets have been upgraded several times in both spatial and temporal resolutions.” The paper documents the steps the authors took to reprocess the data in order to make it more consistent and accessible, which ultimately makes it easier for users to study long-term trends.

Timeline of ice chart evolution and frequency, from the research paper described above (Yang et al 2020). Credit: Ting-Yi Yang, Cooperative Institute for Great Lakes Research.

Whether you’re looking for decades of Great Lakes ice data or just a few days, GLERL’s got you covered! Looking for more Great Lakes ice cover information? Visit our ice cover homepage here.

MODIS satellite image of ice cover on the Great Lakes, March 16, 2014. Credit: NOAA Great Lakes CoastWatch.


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New science with historic data: 15 years of Great Lakes environmental data archived in NOAA data repository

With a network of experimental buoys that are constantly recording new data every few minutes, the amount of data the NOAA Great Lakes Environmental Research Laboratory (GLERL) has collected in the past 15 years is massive – and prepping it all to be archived in an official data repository is no small task. This year, thanks to the hard work of GLERL’s data managers and engineers, the Great Lakes environmental data collected by NOAA GLERL’s real-time buoys has been archived with NOAA’s National Centers for Environmental Information (NCEI) data repository. NCEI hosts and provides public access to one of the most significant archives of oceanic, atmospheric and geophysical data in the world.

A NOAA GLERL Real-Time Coastal Observation Network (ReCON) buoy in Lake Michigan.

An ever-growing collection of Great Lakes data

This real-time Great Lakes observational data archived in NCEI has been collected over time by sensors on coastal buoys as part of GLERL’s Real-Time Coastal Observation Network (ReCON). Each of ReCON’s 16 buoy stations collects meteorological data and provides sub-surface measurements of chemical, biological, and physical parameters (things like wave height, dissolved oxygen, chlorophyll, and water temperature). Totaling an impressive 2,055 data files, this data spans 15 years – from the inception of the first ReCON station in 2004 through the end of the 2019 field season. The data collected by GLERL’s ReCON buoys in the past 15 years are unique and valuable, and now that they are properly processed and easily accessible in the NCEI archive, they can be used in a variety of ways.

Using historic data to improve scientific models

While the near real-time info that our experimental ReCON buoys provide is great for helping you decide whether to hit the water for a day of boating or fishing, their usefulness doesn’t stop there. This Great Lakes ReCON data – both old and new – is incredibly useful to state and federal resource managers, educators, and researchers. For example, scientists can use the historic datasets to test the accuracy of their models, a process known as ‘hindcasting.’ When using archived data for hindcasting, researchers enter data for past events into their model to see how well the model’s output matches the known results. One cool example of hindcasting is the animation below that shows the Lake Superior wind and wave conditions that led to the sinking of the Edmund Fitzgerald in 1975.

Animation created with hindcasting that shows significant wave height and wind field, final voyage of the Edmund Fitzgerald, Nov 9-11, 1975.

As for the fact that ReCON data is collected in near real-time, these convenient same-day measurements can help determine whether or not a hypoxic (low oxygen) event will occur, detect nutrients contributing to harmful algal blooms, and even provide crucial data to the NOAA National Weather Service for coastal forecasting.

Water intake crib off the coast of Lake Erie in Cleveland, Ohio. Real-time data collected by NOAA GLERL’s ReCON buoys can help warn water intake managers of potential hypoxic events, which can affect drinking water quality.

Putting our data to the test

NOAA GLERL data manager Lacey Mason and marine engineer Ron Muzzi are in charge of preparing and submitting the data to NOAA’s NCEI data repository. Preparing the data to be archived involves performing quality assurance checks to ensure that it meets the Integrated Ocean Observing System’s (IOOS) standards set specifically for real-time oceanographic data. All of the data undergoes multiple quality tests before being archived, and each data point is flagged to indicate its reliability – whether it passed all tests, is suspect, or failed one or more tests.

In addition to being available on NOAA GLERL’s website and now the NOAA NCEI data repository, GLERL’s real-time buoy data can also be found on NOAA’s National Data Buoy Center website. The NCEI archive is fully updated with all of GLERL’s real-time data through 2019, and GLERL will continue to add new data to the archive on a yearly basis. The archived data can be accessed from the link here: https://doi.org/10.25921/jvks-b587.


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Sinkhole Science: Groundwater in the Great Lakes

If you followed our fieldwork last summer, you probably remember hearing about our research on the fascinating sinkholes and microbial communities that lie at the bottom of northern Lake Huron off the coast of Alpena, MI. Now you can experience this research as a short film!

NOAA GLERL has partnered with Great Lakes Outreach Media to create a short film entitled Sinkhole Science: Groundwater in the Great Lakes. It was recently featured on Detroit Public Television’s Great Lakes Now program as well as the Thunder Bay National Marine Sanctuary’s International Film Festival. 

In the film, you’ll learn how NOAA GLERL’s Observation Systems and Advanced Technology (OSAT) branch studies how these sinkholes impact the water levels and ecosystems of the Great Lakes. GLERL’s OSAT Program Leader Steve Ruberg explains the high-tech gadgets involved in this research, including a remotely operated vehicle (ROV), a tilt-based current sensor, and temperature strings to determine vertical movement of groundwater entering the lakes through the sinkholes.

Hit “play” to dive into the exciting world of GLERL’s sinkhole science!

Researchers from NOAA GLERL’s Observation Systems and Advanced Technology team set out on the R/V Storm to study sinkholes on the floor of northern Lake Huron off the coast of Alpena, MI. Photo: Great Lakes Outreach Media
Researchers on NOAA GLERL’s R/V Storm deploy a remotely operated vehicle (ROV) to observe sinkholes at the bottom of Lake Huron off the coast of Alpena, MI. Photo: Great Lakes Outreach Media
NOAA GLERL’s OSAT Program Lead Steve Ruberg and Instrument Specialist Steven Constant observe a sinkhole via live video feed from the ROV. Photo: Great Lakes Outreach Media
NOAA GLERL Marine Engineer Kyle Beadle controls the ROV in order to observe sinkholes from the R/V Storm. Photo: Great Lakes Outreach Media
NOAA GLERL Instrument Specialist Steven Constant and Vessel Captain Travis Smith monitor the ROV as it dives beneath the surface to observe a sinkhole. Photo: Great Lakes Outreach Media


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Millions of Microbes: The Unexpected Inhabitants of Lake Huron’s Underwater Sinkholes

When most people think of sinkholes, a massive cavity in the ground opening up and swallowing a car is what usually comes to mind. But when scientists at the NOAA Great Lakes Environmental Research Laboratory (GLERL) hear “sinkholes,” their minds jump to an unusual place — the bottom of a Great Lake.

Aerial view of research boat on green water
Researchers on GLERL’s R/V Storm study sinkholes in northern Lake Huron off the coast of Alpena, Michigan. (Credit: David J Ruck/Great Lakes Outreach Media)

Thousands of years ago, off the coast of Alpena, Michigan, patches of ground beneath Lake Huron collapsed to form a series of underwater sinkholes — some measuring hundreds of feet across and up to 60 feet deep. You may have read this NOAA.gov article about how these sinkholes are contributing water to Lake Huron, but did you know they also support a huge kingdom of microorganisms?

Microbes might be tiny, but they’re one of the biggest research topics in the Great Lakes. They thrive near the sinkholes because the groundwater seeping in has the perfect chemistry for their survival: low oxygen levels and lots of chloride and sulfate, which come from the dissolved limestone underlying the lake. These factors make the sinkholes inhospitable for fish and other wildlife normally found in the Great Lakes, which means these microbes have a much easier time surviving there than other creatures. With perfect living conditions and little competition, they’re so abundant that they form purple, green, and white microbial mats that cover the lake floor like a colorful carpet.

Floor of Lake Huron covered by purple and white microbial mats with bubbles in them.
Purple microbial mats in the Middle Island Sinkhole in Lake Huron, June 2019. Small hills and “fingers” like this one in the mats are caused by gases like methane and hydrogen sulfide bubbling up beneath them. (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

Scientists at GLERL are collaborating with partners from the University of Michigan and Grand Valley State University to see just what these microscopic lake dwellers can teach us. This video by Great Lakes Outreach Media highlights how they can even give us a deeper insight into the history of Earth itself.

Associate Professor Greg Dick from the University of Michigan discusses cyanobacteria’s important role in Earth science. This clip is from Great Lakes Outreach Media’s upcoming documentary, “The Erie Situation.”

Some sinkholes are so deep that sunlight can’t reach them, but that doesn’t stop some microbes from calling them home. They’re able to live their entire lives in complete darkness, because they get their energy from the added minerals in the water rather than from sunlight — a process called chemosynthesis. But whether they need sunlight or not, several of the microbial species present have proven to be full of surprises.

“In the near-shore systems, the cyanobacteria we found have DNA signatures that come closest to comparing to the cyanobacteria found at the bottom of a lake in Antarctica. So that’s a strange coincidence,” said Steve Ruberg, the scientist in charge of sinkhole research at GLERL. “Some of the other bacteria we’ve found in the deeper systems have only been found off the coast of Africa.”

Fish sitting on a rock, which is covered by purple and white microbes
A burbot resting on rocks covered in purple and white microbial mats inside the Middle Island sinkhole in Lake Huron. (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

The particular sinkholes we’re studying are located within NOAA’s Thunder Bay National Marine Sanctuary, an area of Lake Huron that’s federally protected for the purpose of preserving nearly 200 shipwrecks. In fact, the only reason we know about these sinkholes is because they were discovered by accident only 18 years ago, on a research cruise documenting the shipwrecks.

Close up of rocks covered in purple, white and green microbes on the bottom of Lake Huron, with a diver in the background.
A diver observes the purple, white and green microbes covering rocks in Lake Huron’s Middle Island Sinkhole (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

So why did this microbial paradise come into existence in the first place? The story goes back much further than the sinkholes’ discovery in 2001. About 400 million years ago, before the Great Lakes even existed, a layer of limestone bedrock formed beneath what is now Lake Huron. Then around 10,000 years ago, underground caves were created when a chemical reaction between the limestone and acidic groundwater dissolved away holes in the bedrock. All that was left were weakly supported “ceilings” that eventually collapsed into the sinkholes we — and the microbes — know and love today.

Close up of rocks covered in purple, white and green microbes on the floor of Lake Huron
Purple cyanobacteria and white chemosynthetic mats on the floor of Lake Huron with Lowell Instruments current meter. (Credit: Phil Hartmeyer, NOAA Thunder Bay National Marine Sanctuary)

Since Lakes Michigan and Erie have the same limestone bedrock as Lake Huron, GLERL scientists think these lakes could be home to more of these fascinating underwater features. So while the excitement of this fieldwork has died down for the year, our research on Great Lakes sinkholes and their tiny inhabitants is far from over.