Structure and interactions in a cave guano-soil continuum community

Abstract

Bat guano represents an important food resource for cave-dwelling organisms, hosting up to entire communities in a single deposit. Sampling conducted in guano and its interface with the adjacent soil revealed a wide variation in physicochemical parameters (nitrogen, phosphorus, organic matter, pH and moisture) along that continuum. The invertebrate orders that showed the greatest abundance and species richness were: Mesostigmata, Sarcoptiformes and Trombidiformes, all belonging to subclass Acari. The results clearly showed that mite species are the most abundant group in guano deposits. Such species can directly or indirectly feed on this food resource. The abiotic factors of the guano significantly explained some community parameters. Furthermore, moisture was the parameter that best explained the abundance distribution for the most common mite species. Lastly, a trophic web of the most abundant species in the guano was devised based on literature data, interspecies correlation, preferences for microhabitats and abundance rates of the populations. It was possible to observe that the temporal changes in the guano deposit determine a successional process in the community, including the trophic web structure.