ABSTRACT--Twelve central Tennessee caves were sampled in the Nashville Basin and Highland Rim subsections of the Interior Low Plateaus physiographic province. Emphasis was placed on sampling caves inhabited by the gray bat (Myotis grisescens) and characterized by rich nutrient supplied from guano. A total of 32 obligatory cavernicoles was recorded, ranging from widespread species to single cave endemics. Invertebrates observed in these caves included crustaceans (16 species), pseudoscorpions (2 species), spiders (7), millipedes (8), a dipluran (1), psocopteran (1), collembolans (18), beetles (22), and flies (6). Berlese extraction of guano from three cave systems resulted in the recovery of several species of mites (Acari), including two species of Macrocheles (Macrochelidae). Factors that may affect the composition of these bat guano communities are discussed.

Since 2000, JJL has been sampling invertebrates in Tennessee caves (Lewis, 2001, 2002, 2004, 2005a, 2005b, 2006; Lewis and Lewis, 2007). Over 9,000 caves are now recorded from Tennessee and are inhabited by one of the most species rich subterranean faunas in temperate North America (Culver et al., 2006). In 2006, a project was initiated by The Nature Conservancy focusing on caves recognized as roost sites for the endangered gray bat (Myotis grisescens). In addition to the bats, these caves provided potential habitats for guanophilic, as well as stygobitic, invertebrates.

Some of the more important aquatic invertebrates of caves are flatworms, copepods, ostracods, isopods, amphipods, and crayfish. More abundant terrestrial invertebrates are snails, isopods, mites, spiders, millipedes, springtails, cave crickets, beetles, and flies. There is relatively little information on guano invertebrate communities of caves. Fletcher (1982), in a study of the microbial ecology of a community living on gray bat guano in a Missouri cave, noted the presence of 30 species of mites. The most common taxa were undetermined oribatids (Ceratozetes sp., Banksinoma sp., Multioppia sp.), Rhagidia sp., Ereynetes sp., and Macrocheles penicilliger. Of these, the first three presumably consume microbes growing on the guano, while the latter three are microarthropod predators. The presence of mites was correlated with the age of the guano. Freshly deposited mite-free material developed populations that peaked at 38 days, with 186 mites/pitfall trap. After one year, the average number of mites per pitfall dropped to 100, and in guano estimated to be five years old, only 62 mites per pitfall were present.

Many of the sites visited are managed for the preservation of their bats, and several of them have been purchased to that end. The bat populations of these caves were relatively well known through periodic census-taking, but the other inhabitants remained mostly unknown. The purpose of the project was to identify other species worthy of conservation efforts at the same sites.

Sampling of invertebrates in caves inhabited by large numbers of M. grisescens was problematic, because some of the caves are closed to visitation during the summer when maternity colonies are present. The caves are likewise closed during the winter when they are occupied as hibernacula. Thus, in some of the caves only a narrow window exists in the...