Fig. 1: The breadth of subterranean habitats considered in this perspective.
From: Perspectives and pitfalls in preserving subterranean biodiversity through protected areas
The overarching classification (Subterranean [S], Subterranean–Freshwater [SF], Subterranean–Marine [SM]) is based on ref. 75. A Terrestrial caves in different substrates (e.g., karst, lava, ice, salt); B Artificial subterranean habitats (e.g., mines, bunkers, blockhouses, transport tunnels, tombs); C Shallow and deep fissured systems; D Aquifers and groundwaters (e.g., subterranean lakes, rivers, ponds); E, F Springs, wells, and other surface-subterranean ecotones (e.g., voids within vadose zone in karstic and fissured aquifers, interstitial habitats such as hyporheic zone); G Artificial aquatic subterranean habitats (e.g., tanks, aqueducts, water pipes); H Marine caves, hosting coastal pools and subterranean voids connected to marine waters; I, J Anchialine caves and pools contain tidally influenced water bodies where fresh, brackish, and salt waters mix through subterranean connections between the sea and the groundwater. Anchialine pools are also exposed to open air and sunlight. Photo credits: A, B, D, G–I uPIX Fotografia Ipogea; C, E, F Ilaria Vaccarelli; J David Brankovits.
