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2003
RIVER
RESCUERS
UM'S NEW RIVERINE SCIENCE CENTER
POISONED
HEARTS
ARSENIC EFFECTS ON CARDIOVASCULAR HEALTH
WATER
WIZARDRY
BIO STATION'S NEW FLOOD PLAIN MODEL
RIVERS
THAT TIME FORGOT
AN UNDISTURBED RUSSIAN WILDERNESS
SODIUM
SOLUTIONS
COALBED METHANE IN EASTERN MONTANA
HEAVY
METAL
SCIENTISTS STUDY IMPACT OF METALS ON MICROBES
COTTONWOOD
CONUNDRUM
MONTANA'S DISAPPEARING RIVER TREES
WATER
WARDENS
UM'S WATERSHED HEALTH CLINIC
TALLYING
TADPOLES
STUDYING MONTANA AMPHIBIANS
FISH
FINDERS
DNA IN WATER REVEALS LOCATION OF FISH
WET
AND WILD
A PRIMER ON MONTANA AQUATIC LIFE
WATER
THAT WAS
THE SECRETS OF GLACIAL LAKE MISSOULA
NEWS
TO USE
THE WEIRD LIFE CYCLE OF SWIMMER'S ITCH
BACKTALK
GIARDIA: A WATER DRINKER'S GUT-WRENCHING SURPRISE
Scientists study impacts on river microbes
By GARY JAHRIG
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| Not a rock band (left to right): Matthias Rillig, Jim Gannon, Bill Holben, and Johnnie Moore. |
When a team of University of Montana scientists decided they wanted to study how heavy metals affected life in the Clark Fork River, they opted to start at the bottom. The bottom of the food chain, that is.
"Basically there has been a lot of concern about metal contamination in rivers," says Johnnie Moore, a UM geology professor for the past 27 years. "There's been a lot of lab testing done on fish. We wanted to try something different."
Beginning in 2000, Moore, along with UM colleagues Bill Holben, a professor of microbial ecology; Jim Gannon, a professor of environmental microbiology; andMatthias Rillig, an assistant professor of microbial ecology, began overseeing a study on how metals in the Clark Fork affected the microbial community.
"We wanted to study a selection of metals, not just single elements like arsenic or cadmium or copper. We wanted to study them altogether as they are found in the environment," Moore says.
And they wanted to find a way to measure what effect the metals — from years of upstream mining — had on the river's ecosystem. So rather than study fish or the insects fish eat, the UM team set their focus on microbes — microscopic single-celled organisms found on rocks in the river.
"Basically it's the slime on the rocks you see in the river," Moore says. "Bacteria and other microbes are the base of the ecosystem. We decided we didn't want to work on organisms above bacteria in the ecosystem because we wanted to see how the foundation of the ecosystem was affected by metal contamination."
A river's lifeblood
Holben, who has been a faculty member in UM's Division of Biological
Sciences for the past eight years, says the team settled
on microorganisms because they "are the true base of
the food web" in the river.
"The basis of the food chain in the water and sediments is that bacteria consume organic carbon. Insects then consume the bacteria. And insects are then eaten by fish," Holben says.
To fund their research, the UM team secured two two-year grants from the U.S. Environmental Protection Agency, worth $140,000 per year. Based on the findings of the current research project, Holben says, the UM team hopes to secure additional funding from the National Science Foundation to continue the study.
Moore and Holben believe their research into river contamination is beneficial to UM because it gives both undergraduate and graduate students a chance to participate in a hands-on science project. So far, results from the research have been presented in a master's thesis and doctoral thesis for two students who have graduated from UM. Several other students currently are working on the evolving project.
And the subject of their study also could prove beneficial to residents of Montana, where fishing is a cherished pastime and water quality is an issue of intense interest.
"One of our goals is to add new knowledge about the river system — additional knowledge of how ecosystems work and how humans affect them," Moore says. "Hopefully we can generate a better understanding of how contaminated rivers work and how to measure that contamination.
"And along the way, we're training scientists to solve these problems in other places and on other rivers."
A tale of six sites
When research began three years ago, the UM team settled on
six test sites on the Clark Fork — ranging from Silver
Bow Creek, just west of Butte, to Rock Creek, just east of
Missoula. What the scientists wanted to look at was the concentration
of metals in the sediment in the Clark Fork. For years, mining
operations in Butte and smelters in Anaconda dumped huge
amounts of metals into the river.
Moore says researchers have found high concentrations of metals such as arsenic, cadmium, copper, lead and zinc, with different test sites yielding concentrations of different metals. The UM study's goal is to compare what kinds of microorganisms are found living in the presence of different concentrations of metals at various spots in the river.
Moore handles the geological testing for metals, while Holben, Gannon and Rillig oversee the biological research.
"We isolate the DNA from the organisms living on the sediments," Holben says. "We determine what kinds of bacteria are in the community. We compare samples from one contaminated site to others. We check to see if the same bacteria are present."
Holben says the team has created a "contamination index" to represent the total concentrations of different metals found along the river. He says the researchers found that different types of microorganisms thrive in areas contaminated with different amounts of metals.
"We test a bucket full at each site," Holben says. "We have found that the sediment is full of different things at different sites."
But that does not appear to have had an impact on the number of microorganisms living in the river.
"The idea is that the short-term response may impact numbers and the activity of the microorganisms there when the contamination first enters the stream. But over time, the community grows to have the same number of organisms as the uncontaminated sites.
It's become a more metal-tolerant community," Holben says. "Some groups of bacteria are more apparent where there are heavy metal concentrations, while others are less abundant."
Holben says that since certain insects appear to prefer certain kinds of bacteria, affecting the makeup of the microbial community may in turn affect the insect community and ultimately the larger organisms such as fish.
Moore says the contamination in some areas of the river is great. "In some places there are 100 times more metal contamination than what would normally be there," he says. "So we see how the micro-organisms have responded to the changes.
"The bacteria have built up their ability to deal with metals over a number of years. The environment appears to select certain organisms that can deal with metals."
Holben and Moore believe their research into microorganisms will prove to be an accurate indicator of the impacts of metals on aquatic life in the Clark Fork and other rivers.
"We want to establish the microbial community as a more sensitive indicator of toxic effects of heavy metals on rivers," Holben says.
Adds Moore: "It's very difficult to get ecosystem data with insects or fish. With bacteria, you can monitor very small changes in the ecosystem very rapidly."