Invisible Invasive Species Threaten Ecosystems

While Asian carp, gypsy moths and zebra mussels hog invasive-species headlines, many invisible invaders are altering ecosystems and flourishing outside of the limelight. A study by Elena Litchman, Michigan State University associate professor of ecology, sheds light on why invasive microbial invaders shouldn't be underestimated.

"Invasive microbes have many of the same traits as their larger, 'macro' counterparts and have the potential to significantly impact terrestrial and aquatic ecosystems," said Litchman, whose research appears in the December issue of Ecology Letters. "Global change can exacerbate microbial invasions, so they will likely increase in the future."

One example is in the Great Lakes, a brackish diatom (a microscopic alga), has colonized Lake Michigan probably via ballast-water discharge and is now the largest diatom in the waterways. Also while many people have a working knowledge of the American chestnut blight, which was caused by a pathogenic parasitic fungus, most invasive microbes fly beneath the radar of the public and scientists alike. Virtually nothing has been published on the potential of nonpathogenic microbes on a large scale, according to Litchman. The chestnut blight dramatically altered forests and now the spread of West Nile virus is associated with significant bird deaths," she said. "Currently, there are no published examples of the impacts of invasive nonpathogenic microbes, but there is growing evidence that they could change ecosystems in equally dramatic fashion." The lack of attention to microbial invasions compared to macroorganisms is partly because their cryptic nature and the difficulty of detection. Lack of detection combined with climate change could potentially increase these microbial invasions, which could continue to grow as the earth's weather patterns change, Litchman said.

http://www.sciencedaily.com/releases/2010/12/101207143216.htm