Alarmed by the Invisible Invasive Species

When we hear of invasive species we think at the Asian carp, the zebra mussels or at the gypsy moths, because it's what we hear of most, but a study conducted by a Michigan State University professor, warned that there are much smaller invaders, that are almost invisible but which affect ecosystems and keep flourishing when no one pays attention.

The study was led by Elena Litchman, Michigan State University associate professor of ecology, and it gives some reasons for which invasive microbial invaders shouldn't be overlooked, nor underestimated.

Most people wander about microbial invasions far less than about macroorganisms, mostly because they are very difficult to detect, and they can hide many mysteries.

The problem, according to Litchman, is that this lack of detection along with the ongoing climate change, will only increase these microbial invasions.

She explained that the “increasing air temperatures have been implicated in the spread of malaria and other pathogenic microbes into higher altitudes and latitudes.

“Likewise, climate change could stimulate invasions by tropical and subtropical non pathogenic microbes into temperate latitudes.”

Scientists as well as ordinary people, are informed about the spread of Asian carp, zebra mussels and gypsy moths, but they know mostly nothing about exotic cyanobacteria, also called 'blue-green algae' – which appeared in North American and European lakes, or about the nitrogen-fixing rhizobium – a soil microorganism that migrated from Australia to Portugal.

Another example is a brackish diatom that lives in the Great Lakes, and that has colonized Lake Michigan, most probably through via ballast-water discharge, turning into the largest diatom in the waterways.

Litchman explained that “invasive microbes have many of the same traits as their larger, 'macro' counterparts and have the potential to significantly impact terrestrial and aquatic ecosystems.

“Global change can exacerbate microbial invasions, so they will likely increase in the future.”

Moreover, there are almost no publications on the potential of non pathogenic microbes on a large scale, according to Litchman.

She said that “from scientific research, we know that the chestnut blight dramatically altered forests and how the spread of West Nile virus is associated with significant bird die-offs.

“Currently, there are no published examples of the impacts of invasive non pathogenic microbes, but there is growing evidence that they could change ecosystems in equally dramatic fashion.”

This research appears in the December issue of Ecology Letters.

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