Image of the Day: Springtails As Environmental Monitors

By Bruce G. Marcot, Ecology Picture of the Week:

This week's image shows two views of a relatively common but very tiny denizen of forest and prairie soils -- the springtail Tomocerus flavescens.  Both views are under a 60x microscope lens.  The top image was made using reflected light ("enhanced brightfield microscopy") to show external structures, and the bottom image was made with transmitted light ("transmitted light microscopy") to show internal structures.  

This is a most interesting species.  It seems to be able to exist in a wide variety of locations and ecosystems but may not tolerate much disturbance.  I found many of them in the volcanic soil of old-growth conifer forests, north of Mount St. Helens in the Cascade Mountains of southern Washington State, USA.  The species also has been reported in native unburned prairie soils (Brand 2002, Brand and Cunn) and as part of the invertebrate cave fauna in eastern USA (Holsinger and Culver 1988).   

So why does it seem to like undisturbed environments?  There may be several reasons.  For instance, laboratory experiments (Knight and Angel 1967) suggest that this species prefers to consume fungal spores which may be more common in less disturbed and unburned forest, woodland, and prairie environments.  Also, field studies (Irmler 2004) suggest that springtails tend to migrate away from waterlogged and flooded soils in alder forests.  Other studies (Rusek and Marshall 2000) suggest that springtails may be sensitive to airborne pollutants.  

Thus, this species might serve as a useful indicator of pollutants and the degree of disturbance of many different types of ecosystems.  Springtails in general are important indicators of environmental pollution (Hopkin 1999).

--Bruce G. Marcot

Image and text © Bruce G. Marcot, Ph.D. Research Wildlife Ecologist,
who produces the Ecology Picture of the Week website.