Duality of terrestrial subterranean fauna

Abstract

Terrestrial animals in subterranean habitats are often classified according to their degree of morphological or ecological specialization to the subterranean environment. The commonly held view is that, as distance into a cave increases, the frequency of morphologically specialized, i.e., troglomorphic, species or ecological specialization will increase. We tested this hypothesis for the fauna in 54 caves in Slovenia-the classical land for subterranean biology. We found that there exist two ecologically well separated terrestrial subsurface faunas: one shallow and one deep. 1) The shallow subterranean fauna, adapted to the terrestrial shallow subterranean habitats (SSHs) in the upper 10 m of subsurface strata, is most diverse. It consists of randomly distributed non-troglobionts and a major group of troglobionts adapted to the soil root zone. 2) The deep subterranean fauna is represented by a minor group of troglobionts, adapted to caves. Troglobionts are strictly divided between the two faunas. There is strong evidence that in karstic ecosystems with deep-rooted vegetation this might be a global pattern, or that in these locations only the shallow subterranean fauna exist.

The conservation value of karst dolines for vascular plants in woodland habitats of Hungary: refugia and climate change

“…Although karst ecosystems are usually diverse and are very important in many aspects of ecological research (e.g. Cardoso, 2012;Novak et al, 2012), there are still many open questions about how karst surfaces will change under future global warming.…”

Contribution of non-troglobiotic terrestrial invertebrates to carbon input in hypogean habitats

“…Such a distribution is also true for all the species under study, which are most abundant in the upper 10 m beneath the surface (Novak et al 2012). Gibert (1986) found that dissolved organic carbon is the most important among abiotic carbon sources in subterranean water.…”

“…In contrast to the general assumption and our hypothesis, in Central European caves, non-troglobiotic taxa contribute very little to the deep troglobiotic species. Additionally, predated individuals contributed maximally 0.15% C. This low carbon input might be the main reason why a major group of troglobionts inhabit shallow subterranean habiinhabit shallow subterranean habitats (Novak et al 2012).…”

“…The first is a field data set on the more abundant invertebrates (listed in Novak et al 2012) from 51 caves and three abanfrom 51 caves and three abanfrom 51 caves and three abandoned mines in central and northern Slovenia (listed and mapped in Novak 2005; in the following: caves). The second data set includes biometric, biochemical and cytological data provided by a separate study of 11of the more abundant non-troglomorphic invertebrate species which inhabit these caves during winter or which are important for their large mass (Tab.…”

“…Food takes the form of dissolved organic carbon (DOC), fine (FPOM) and coarse particulate organic matter (CPOM), eggs, cadavers, excrement and predated specimens. A conspicuous amount of organic carbon is incorporated in nontroglobiotic animals (i. e., trogloxenes and troglophiles; see Novak et al 2012 for comments) that move daily or seasonally between surface and subterranean habitats and supply food directly to the subterranean communities (Fong 2011).…”