Food resource availability in a quartzite cave in the Brazilian Montane Atlantic Forest

Abstract

The litter produced in the exokarst and imported into a quartzite cave were measured, as well as the latter’s availability and consumption in aquatic and terrestrial cave habitats. In the exokarst, the litter production increases during the rainy season, although the actual importation of this coarse particulate organic matter into the cave is mainly due to the wind. The sandstone soil and the percolation of water through the epikarst have a filtering effect, and the CPOM input into deeper zones in the cave is limited, despite the presence of a stream. In the terrestrial environment of the cave, percolating water increases plant detritus consumption somewhat during the rainy season, although it is still low, due to the generally dry soil conditions in the cave. The cave can be characterized as an oligotrophic system, especially in the deeper zones, with most invertebrate species occurring near the cave entrances, where the CPOM is more abundant. The forest promotes the presence of trogloxene taxa (opiliones: Goniossoma sp. and Araneae: Enoploctenus sp). Guano in the deeper zones of the cave is extremely scarce and old, so its importance as a basic resource for the cave fauna is quite limited. Conversely, termite colonies and scarce roots recruit trophic resources for the troglophile and troglobite species in the deeper zones. Several cave species were observed in these areas, apparently feeding on roots and the debris left by termites.