Microbial Ecology of a Bat Guano Community

Date of Graduation

Spring 1982


Master of Science in Biology



Committee Chair

Roar Irgens


Guano from the Gray Bat, Myotis griscescens, represents a major nutrient input into cave systems of Southern Missouri. It forms the base of a dynamic community of microflora and microfauna in a controlled environment. The guano community is found in what normally would be considered a nutrient deficient environment, but it is representative of decomposer communities found elsewhere. The relationships between the biochemical composition, microflora, and microfauna were studied using biochemical, agar film, dilution plate, pit-fall trap, direction observation, and photographic techniques on guano of various ages. Fresh guano is initially dominated in number and biomass by a bacterial flora primarily of enteric origin. Older guano remains numerically dominated by bacteria but fungi dominate in the biomass category. The oldest guano, ca five-years-old becomes dominated in number and biomass by coccoid-shaped bacteria. Molds appear a few days after guano deposition and undergo an involved succession that appears to be based on spore germination times and nutritional factors. After several weeks, actino-mycetes appear but actinomycete biomass could not be distinguished from bacterial. The microfaunal populations included nematodes, mites, collembola, psocids, fungus gnats, and pseudoscorpions. Nematodes and mites were the numerically dominant microfaunal populations. Molds appear to influence the microfaunal populations through various interactions. Multiple correlations between guano biochemistry, microflora, and/or microfauna were noted but most were difficult to interpret. Hydrogen ion concentration (pH), lack of "weather", and perhaps molecular recalcitrance are all significant limiting factors in the guano community and probably account for the accumulation of guano in piles.

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© M. W Fletcher