Managing Microbial Communities in Caves

Abstract

Microbial communities in caves vary from striking microbial mats observed in many lava tubes worldwide, to occasional colonies on the wall, to invisible biofilms on rock walls and ceilings of caves, to microbial end products, such as manganese oxides. The investigations of the last decade, using culture-independent techniques in which we extract DNA from environmental samples and sequence clones to identify organisms present based on their genetic sequence, have revealed a wealth of microbial species never before described. These microorganisms represent a minimally explored treasure trove of organisms that can be impacted by the actions of humans living above caves and exploring within caves. The degree to which we impact cave microbial communities depends on the nature of the cave. Mammoth Cave in Kentucky, USA, and other similar caves, have rivers or streams running through major portions of the cave. Water flowing into caves may either bring plumes of pollutants to many parts of the cave and/or may help to wash away some impact caused by human visitation. Arid-land caves, such as Lechuguilla Cave in New Mexico, USA, that lack much in the way of flowing water, may be subjected to other kinds of impacts. Several strategies have been suggested to lower the impact that we explorers, scientists, and people living above caves have on cave microbial communities in order to preserve them for future study. Cave microbial communities can represent an extremely valuable resource that is worth protecting by modifying our behavior in visiting and living above caves.