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Scientists make discovery about Lake Huron sinkholes

February 26, 2009
Patty Ramus

Scientists have discovered that organisms found at the bottom of two Lake Huron sinkholes within the Thunder Bay National Marine Sanctuary are similar to organisms found on the bottom of permanently frozen Antarctica lakes.

Last summer a group consisting of nutrient chemistry, geochemistry, groundwater geology and oceangraphy experts traveled to Alpena to begin gathering data as part of a research project funded through the National Oceanic and Atmospheric Administration's Office of Ocean Exploration.

The group has been studying two locally known sinkholes in El Cajon Bay and near Middle Island, and a sinkhole discovered in 2001 near a NOAA-sponsored shipwreck survey. The recently discovered sinkhole is located approximately 10 miles east of Middle Island. In September 2008, the team installed instruments to monitor lake conditions in the sinkholes until they're removed in May.

An article about the team's discoveries was published Tuesday in Eos, a publication of the American Geophysical Union. The piece was co-authored by Stephen Nold, a molecular ecologist at the University of Wisconsin-Stout, Bopaiah Biddanda, research scientist with the Grand Valley State University's Annis Water Resources Institute, Steve Ruberg project leader from NOAA's Great Lakes Research Laboratory in Ann Arbor., Jeff Gray, Thunder Bay National Marine Sanctuary superintendent, and Scott Kendall and T. Garrison Sanders of the Annis Water Resources Institute.

During the project the team has looked to determine the flow of groundwater out of the system and its age. Groundwater, from this geological feature, flowing into the bottom of the sinkhole often remains at the bottom because it is more dense than the water on the surface. The groundwater has an impact on lake levels, Ruberg said.

"Information from this specific site may allow us to do better lake levels estimates in the future," he said.

According to Biddanda, the groundwater flowing into the bottom of these sinkholes contains dissolved items including sulphates, carbonates and chloride. It hugs the lake floor and provides a stable environment for certain organisms to produce.

"The bottom has low oxygen. High sulfur and low oxygen are conditions that prevailed in the early Earth. We're getting a peek into ancient times with these communities," he said.

The high sulfur and low oxygen conditions are ideal for a purple colored cyanobacteria that has managed to thrive in an environment too extreme for other organisms. They also have a different method of producing organic matter. Most plants use water in the photosynthetic process to produce organic matter. The cyanobacteria use hydrogen sulfide to produce organic matter and this is thought to be the origin of the photosynthetic process, Biddanda said.

Biddanda said the cyanobacteria have been found in the two sinkholes near Middle Island because the bottom receives a certain percentage of the surface light.

The bottoms of the sinkholes can be compared to the rainforest in South America because it's different from the rest of the world. The research has found there is high species diversity and they're different than the rest of Lake Huron, Nold said.

"Some of the species we're seeing in Lake Huron are highly identical, if not identical to permanently ice covered lakes in Antarctica," he said.

Nold said these organism could have turned up in different places because the bacteria can be spread throughout the world through vectors including wind or birds. Whether they survive depends on the environment they end up in. The similarities were found by analyzing and comparing DNA sequences.

"We must have the very same habitat as Antarctica in Lake Huron," he said. "One of those genes is nearly identical in both of those habitats."

Researching these organisms can be useful for pharmaceutical or biotechnological applications. These organisms would not have been found if they had not been protected by federal entities such as the marine sanctuary, Nold said.

Patty Ramus can be reached via e-mail at or by phone at 358-5687.



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