Elevated Carbon Dioxide Levels in Bayliss Cave, Australia: Implications for the Evolution of Obligate Cave Species

Abstract

In May and June 1985, the deeper passages of Bayliss Cave, North Queensland, Australia, contained up to 200 times the ambient atmospheric level of carbon dioxide and a water-saturated atmosphere, yet supported the most diverse community of highly modified, obligate, terrestrial cave species yet known. The obligate and facultative cave species were mostly segregated by the environment, with the 24 obligate cave-adapted species being largely restricted to the "bad-air" zone. The discovery of this previously unknown "bad-air," obligate cave community corroborates other behavioral and distributional studies that suggest that cave-adapted animals are specialized to exploit resources within the smaller underground 'voids, where fluctuating carbon dioxide concentrations are theoretically intolerable to most surface and facultative cave species.