The Chemoautotrophically Based Movile Cave Groundwater Ecosystem, a Hotspot of Subterranean Biodiversity

Abstract

Movile Cave hosts one of the world’s most diverse subsurface invertebrate communities. In the absence of matter and energy input from the surface, this ecosystem relies entirely on in situ primary productivity by chemoautotrophic microorganisms. The energy source for these microorganisms is the oxidation of hydrogen sulfide provided continuously from the deep thermomineral aquifer, alongside methane, and ammonium. The microbial biofilms that cover the water surface, the cave walls, and the sediments, along with the free-swimming microorganisms, represent the food that protists, rotifers, nematodes, gastropods, and crustacean rely on. Voracious water-scorpions, leeches, and planarians form the peak of the aquatic food web in Movile Cave. The terrestrial community is even more diverse. It is composed of various species of worms, isopods, pseudoscorpions, spiders, centipedes, millipedes, springtails, diplurans, and beetles. An updated list of invertebrate species thriving in Movile Cave is provided herein. With 53 invertebrate species (21 aquatic and 32 terrestrial), of which 38 are endemic for this unusual, but fascinating environment, Movile Cave is the first known chemosynthesis-based groundwater ecosystem. Therefore, Movile Cave deserves stringent attention and protection.

An annotated checklist of groundwater Cyclopoida and Harpacticoida (Crustacea, Copepoda) from Romania with notes on their distribution and ecology

“…Eucyclopinae is represented by species of the genera Eucyclops (six species) and Paracyclops (three) and were found in all groundwater habitats with a preference for the hyporheic zone of rivers and springs (Damian-Georgescu 1964;Pleşa 1985;Iepure 2007a). Noteworthy to mention is Eucyclops graeteri scythicus described from Movile Cave where it inhabits exclusively sulfidic waters (Pleşa 1989;Sârbu et al 2000;Brad et al 2021).…”

CaveThiovulaceaediffer metabolically and genomically from marine species

“…In Movile Cave, the oxidation of reduced compounds such as H2S, CH4, and NH4 + is the only primary energy source. Thiovulum, a large sulfur oxidizer, often found in close proximity to sediments, microbial mats or surfaces (Marshall et al, 2012;Jorgensen and Revsbech, 1983;Gros, 2017), is part of the Movile chemoautotrophic microbial community, involved in in situ carbon fixation, that represents the base of the cave's food web that supports an abundant and diverse invertebrate community (Sarbu, 2000;Brad et al, 2021). These Thiovulum cells, exceeding 15 µm in diameter, are larger than most known sulfuroxidizers, belonging to the group of giant sulfur bacteria (Ionescu and Bizic, 2019).…”

Sulfidic Habitats in the Gypsum Karst System of Monte Conca (Italy) Host a Chemoautotrophically Supported Invertebrate Community

“…Several studies have underlined how some subterranean ecosystems do not depend entirely on organic matter coming from the surface [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ] but instead, on chemoautotrophic in situ production of organic matter by microorganisms processing different inorganic elements to obtain energy and nutrients. These organisms represent de facto the only possible primary producers inhabiting the subterranean ecosystem.…”