Epigean-Hypogean Continuum concept

Subterranean streams represent unique heterotrophic ecosystems, usually supported by organicmatter imported fromthe surface. Traditionally, the biological communities from subterranean streams were characterized as simple associations, with low diversity and species abundance, comprising mostly aquatic invertebrates connected by few trophic links compared with those of the surface. However, these features have not yet been described in the wider context of fluxes of energy and nutrients through food webs along a gradual switch from autotrophy (dominated by photosynthesis) towards heterotrophy (dominated by detritus) following the surface−subterranean continuum. Combining the most recent predictions of Ecological Stoichiometry and theMetabolic Theory of Ecology, the Epigean-Hypogean Continuum concept (Pacioglu et al., 2021) provides a theoretical framework aiming to explain the patterns observed along the surface−subterranean continuum in streams.