Cryobionts in Snow and Ice Observed with Low Temperature Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM)

TitleCryobionts in Snow and Ice Observed with Low Temperature Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM)
Publication TypeConference Paper
Year of Publication2005
AuthorsWergin W.P., Foster J., Rango A., Josberger E., Erbe E.F., Murphy C.A., Pooley C.D.
Conference NameGeological Society of American Meeting
Date PublishedOctober 18, 2005
ARIS Log Number190014
Keywordscryobionts, nival fauna, snowfields
AbstractNumerous studies have isolated and identified hundreds of species of nival fauna. Some of these species were true cryobionts that inhabited adverse alpine environments, others were merely aeolian fauna that were passively deposited on snowfields by updrafts. Because of the extreme environments in which these organisms are found, studying them in situ is very difficult. However, because similar environments may exist or previously existed on Mars, the growth and analogous fauna could have been supported in the Martian milieu. For this reason, identifying these organisms and understanding the ultrastructural features that enable them to survive in adverse environments is an important endeavor. Recently, our laboratory has been successful in samplying, shipping, storing and imaging snow crystals and ice grains with a technique known as low temperature SEM. Briefly, this technique consists of collecting samples at remote sites and freezing them in liquid nitrogen. All further manipulations, including imaging, are performed at near liquid nitrogen temperatures, thereby insuring that no re-crystallization or sublimation can occur. At several of the collection sites, bacteria, fungi, algae and ice worms were unexpectedly included with the snow and ice samples. As a result, the surface features of these frozen organisms could be observed in true three-dimensions at magnifications of 50,000 times. Furthermore, following imaging in the SEM, algae could be recovered and chemically fixed by freeze-substitution for examination in a TEM where observations revealed the internal ultrastructural features of the cells. We believe that these results demonstrate important new techniques for in situ studies of nival fauna.