Movile Cave

Description

Movile Cave (Mangalia, Romania) represents the access to the first terrestrial self-sustained ecosystem dependent on chemoautotrophically fixed carbon (Kumaresan, 2014; Sarbu, 1996; Sarbu, 1994), ever discovered.

Movile Cave is the hot spot of the sulphurous aquifer located in South Dobrogea, around Mangalia Municipality. The cave is the only human-accessible entrance point to the unique, completely isolated ecosystem associated to the aquifer that is characterised by H₂S and CH₄ rich water and confined airbells with reduced concentration of O₂. Despite the apparently life-incompatible conditions, the aquifer represents the habitat where an astonishingly diverse community of organisms thrives.  

Solely based on the organic matter and energy produced in situ by chemosynthesis, in the subterranean environment, in the absence of any source of light and input of exogenous matter, this surprisingly rich and diverse biocenose is formed of 51 species of invertebrates from which 30 are endemic for this site. The obligate cave dweller species present morphological and physiological adaptations to the underground environment, being an excellent example of both evolution and speciation.

Moreover, this exceptional biocenose provide an overview on the specific relations that form between various species put together in a peculiar environment, mirroring in the same time important geological events such as the Messinian Crisis (~ 5.5 to 5.2 mya) and the Würm glaciations (~15.000 years ago) that triggered the underground colonisation.

• Geographic location and altitude: short description of the proposed property.

The site is represented by Movile Cave, part of the Natura2000 site ROSCI0114 Obanul Mare și Peștera Movile (~12 ha), as access gate to the self-sustained ecosystem associated to the thermal sulphurous aquifer. The cave is located in Dobrogea, a region in South East Romania, at the outskirts of Mangalia Municipality, Constanța County. It is about 3 km away from the Romanian Black Sea coast, at an altitude of ~10 m, and represents the only known human-accessible entrance to the much broader terrestrial chemosynthesis-based ecosystem associated to the deep sulphurous thermal aquifer captive in Barremian-Jurassic limestone.

• Geology of the property and its surroundings, status during cold periods, mention steepness, soils and erosion (if existing)

The description of the geology of the property (Bădescu, 1998). The Movile aquifer is localised in Southern Dobrogea, which is part of the Moesian Platform that stretches along the Black Sea Coast, being limited by the Capidava-Ovidiu fault to the North, the Danube River to the West and extending toward Bulgaria in the South. Rocks of Sarmatian age outcrop in the area in valleys cutting through Quaternary and Miocene deposits settled on Devonian and Silurian formations.

The black shales of Silurian age contain in their upper part, fossil assemblage formed by Monograptus colonus, M. dubius and M. bohemicus (Chiriac, 1968) and are overlain by Devonian or Mesozoic rocks.

The Devonian’s stages are well separated. The Lower Devonian is characterised by black and grey shales progressively replaced by marls and sandy marls. Based on brachiopod, trilobite and lamellibranchiate, Genidian (Spirifer infans, Tentaculites ornatus) is separated by Coblentzian (Asteropyge prostellans, A. asiatica, Chonetes unkelensis) (Chiriac, 1968). The two stages of Middle Devonian, Eifelian and Givetian are well separated since the Eifelian rocks are represented by  an alternation of black shales with marls which pass thedfordensis in the upper part while the Givetian is represented by a shale and black marls complex with Mucrospirifer mucronatus and Atrypa reticularis kusbassica (Chiriac, 1968). Grey and black marls overlain by black bitumineous limestone with fauna typical to the Frasian stage (Mucrospirifer mucronatus, Chonetes rowei, and Eleuterokoma leducensis) form the Upper Devonian layer (Chiriac, 1968).

The Middle (Bathonian and Callovian) and Upper (Oxfordian and Kimmeridgian) Jurassic periods are represented by cores. Dolostones and thin layered limestones that contain a reef fauna with corals Diceras alternate in these Middle Jurassic formations (Chiriac, 1968).

The Jurassic deposits are overlain by Barremian deposits that outcrop West and North-West of Olteni and are encountered in wells in the localities of Negru Vodă, Negreşti, Plopeni and Albești (Chiriac, 1968). Various other Cretaceous stratigraphic units overly this Barremian unit. Reef limestones, marls and shin intercalations of shales are representative for this unit, in which the fauna is represented by Requienia ammonia, Momopleura trilobata, Toucasia carinata, etc.

Albian rocks are represented by a sequence with a micro-conglomerate horizon containing phosphatic fossils and phosphatic concretions overlain by a glauconitic sandstone. Laterally, these facies pass into cross-bedded sandstones and conglomerates. The fauna are characterized by Diadochoceras nodosocostatum, Stoliczkaia dispar and Anahoplites planus.

Deposits of Cenomanian age are present near Independenţa village as well as in bore-holes along a traverse between the municipalities of 23 August, General Scărişteanu, Dărăbani and Mangalia. They are represented by a detrital facies, defined by calcareous, glauconitic sandstones with micro-conglomerates at the base of sequence. As in the Albian, the micro-conglomerate facies contain phosphatic concretions or phosphatic fossils.

Senonian deposits were identified only in bore-holes. They are represented by chalk deposits with siliceous concretions. Glauconitic sandstones or micro-conglomerates overlay the chalk deposits.

The Eocene is represented by strata of Ypressian  and Lutetian ages. The Ypresian is found only in bore-holes in the area delineated by localities 23 August, Cotu Vaii and Mangalia. These deposits are dominated by quartzitic sand and sandstones, sometimes also containing glauconite, and are interbedded with thin limestones. They are characterised by a distinct fauna with nummulites: Nummulites globulus, N. planulatus and N. exilis. In continuity of sedimentation with Ypressian, Lutetian rocks represented by calcarenites with numulites and echinoderms are found in the same area as Ypressian deposits.

Black shales as well as disodilic shales with fish skeletons (Maikop facies) of Oligocene age are present South from the city of Mangalia and around Vama Veche extending in Bulgaria as well (Chiriac, 1964).

Miocene Epoch is present in the area as Sarmatian outcrops representing the Bessarabian and the Kersonian stages.

Movile cave is developed at the depth of 21 m (Lascu, 1995), in oolitic and fossil-rich limestone of Sarmatian age (i.e., late Miocene, about 12.5 Ma) that contains numerous molluscs fossils (Lascu, 1989).

The Quaternary is represented in South Dobrogea by Early to Late Pleistocene, and by Holocene age deposits (Chiriac, 1968). Mainly loess deposits dominate the oldest units with a thickness ranging 15-30 m, with rare fluvial facies. At the base of the loess, a red and green clay unit is present (1 to 5 m thick). Several interbedded paleosoils have been mentioned (Chiriac, 1968) throughout the loess unit. Terrestrial animal fossils, such as rodents and bison, are found in the Middle to Late Pleistocene.

Holocene deposits are present along the valleys, in the floodplain. They are represented by sand and gravel, interbedded with silt and mud.

The region has undergone several tectonic movements, the first one beginning at the end of the Precambrian. The first well documented Phanerozoic tectonic movement is at the end of Silurian period (Chiriac, 1968).  An angular unconformity exists between Silurian and Devonian, the Devonian one presenting slight deformations caused by the Ardenic tectonic phase, which corresponds to the Caledonian Orogeny (Chiriac, 1968).

There are few small angular unconformities within the Jurassic and Cretaceous Units, which suggest that the tectonic movements had minor influence in this region (Chiriac, 1968). The unconformity that exists between Barremian and Albian stages has a larger extent and it has been ascribed to the Pre-Austric phase. Another unconformity has been observed between the Cretaceous and the Eocene, and was probably caused by a side effect of the Laramic movements (Chiriac, 1968).

During the Sarmatian age, the eastern part of South Dobrogea was lifted, a fact that is responsible for the regressive character of the Kersonian stage.

During the Miocene Epoch, tectonic movement of the Moesian Platform continued, associated with Carpathians growth. Additional lifting, during the Pleistocene Epoch, built up an anticline in the central part of the South Dobrogea, with the axis located between Dumbrăveni and Megidia localities.

• Geomorphology

The region is characterised by a peculiar exokarst represented by large sinkholes locally named Obane.

Movile Cave galleries are accessible through a 21 m deep artificial shaft (Lascu, 1995). The substrate is represented by oolitic and fossil-rich limestone of Sarmatian age (i.e., late Miocene, about 12.5 Ma) (Lascu, 1989).

From the very entrance of the main gallery, the smell of rotten eggs typical for sulphur compounds is very strong, and it becomes ever stronger toward the profound part of the cave. Only about 200 m of galleries and passages are human-accessible. Toward the end of the cave, the galleries become wider and higher, their heights ranging from 40 cm to 2,5 m; the walls are soft, easily penetrable by finger and the ceiling becomes cupola shaped, features indicating severe corrosion of the bedrock, as confirmed also by petrographic analysis (Horoi, 1994). Individual oolites detached from the cave walls by selective corrosion accumulate at the base of the walls (Horoi, 1994).

The galleries are distributed on two levels merging in one chamber – the Lake Room. The upper level is very dry and cooler than the lower one that is warmed by thermal sulphide-rich water. Due to this temperature regime, warm vapours produced at the surface of the sulphidic lake raise along the passages into the upper level. Here, the atmosphere is enriched in CO₂ (up to 1.5%), resulting mainly from methane oxidation and metabolic activity of the cave biota as proven by C isotopic analysis (Sarbu et al., 1996).

The difference of about 0.5°C between the walls temperature (19° – 21°C) and the atmosphere, with the latter being warmer (Sarbu and Lascu, 1997) results in water condensation on the cave walls/ceiling and formation of carbonic acid that accelerate the dissolution of the surface of the limestone walls. The superficial corroded layer of bedrock reaches a thickness of up to eight centimetres and consists of uncemented oolites (Horoi, 1994). To this condensation corrosion process, adds the sulphuric acid corrosion, as previously described, as a result of H₂S present in the water. Also, as a consequence of sulphide dissolved in the water condensed on the walls, gypsum crystals form and cover the limestone surfaces.

• Biotopes, biological and/or ecological processes

Movile Cave (Mangalia, Romania) represents the access to the first terrestrial self-sustained ecosystem dependent on chemoautotrophically fixed carbon (Kumaresan, 2014; Sarbu, 1996; Sarbu, 1994), ever discovered.

Developed at the depth of 21 m (Lascu et al., 1995), in oolitic and fossil-rich limestone of Sarmatian age (i.e., late Miocene, about 12.5 Ma) (Lascu, 1989) Movile Cave has two levels, an upper dry one and a lower flooded with water rich in H₂S, CH₄ and NH₄⁺, accessible from the Lake Room (Sarbu, 2000). Dissolved oxygen is measurable only in the first 5 cm from the surface; deeper than that, the conditions are anoxic (Sarbu, 2000). The ceiling of the flooded galleries rises in several places forming air pockets, the so called Air bells, with air unusually rich in CO₂ and CH₄ and poor in O₂ (Sarbu, 2000).

In the Air bells, but not in the Lake Room where O₂ concentration is close to normal, the surface of the water is covered by a microbial pellicle as thick as up to 2 cm, kept afloat by CH₄ bobbles. The biofilm consists of bacteria, archaea and fungi and represents both habitat and food for various protozoans and metazoans.

The cave harbours a biocenosis represented by 51 species of invertebrates, both terrestrial (31 species) and aquatic (20 species), of which, 35 are endemic for Movile Cave or the sulphidic aquifer associated (Sarbu and Kane, 1995; Sarbu, 2017). The protozoan microbiota consists in flagellates and ciliates. About 94.7% of total metazoans living in the microbial mat are nematodes, followed by cyclopoid copepods (3.5%) and ostracods (1.1%). Harpacticoid copepods (Parapseudoleptomesochra italica), gammarids, isopods, acarids, rotifers and gastropods occurred in densities below 1% (Muschiol et al., 2015).

The aquatic species living in the cave belong to the phyla Platyhelminthes (flatworms), Nematoda (round worms), Rotifera, Annelida (segmented worms), Mollusca (snails) and Arthropoda (ostracod, copepod, isopod, amphipod crustaceans and insects) (Sarbu and Kane, 1995). A particularity of the aquatic organisms in Movile Cave is the ability to survive high concentrations of H₂S and very low concentration of O₂/anoxic conditions.

The aquatic species probably colonised the aquifer continuously, through the points of discharge of underground springs along the Black Sea coast and on the bottom of the sulphide rich lakes as well as on the bottom of the sea (Hillebrand-Voiculescu, in press).

Using the molecular clock technique was shown for the aquatic snail Heleobia dobrogica that this species invaded the underground voids associated with the thermal sulphurous water about 2.172 ± 0.171 Mya ago, when both temperature and precipitations decreased, initiating the glacial period in Europe that predated the Pleistocene (Falniowski et al., 2008).

Referring to the terrestrial fauna, twenty-three species of terrestrial invertebrates belonging to the classes Arachnida, Crustacea, Myriapoda and Insecta are endemic for the Movile Cave and/or for the associated ecosystem (Sarbu and Kane, 1995). They present morphological adaptations to the dark environment, typical for obligate cave-dwelling organisms, such as lack of eyes, depigmentation, and elongated antennae and legs (e.g. Lascona cristiani, Hahnia caeca, Nesticus sp.nov., Trachelipus troglobius).

The colonisation of the underground environment by these species was probably triggered first by the Messinian Crisis about 5.5 to 5.2 mya and then by the Würm glaciation, about 15.000 years ago (Sarbu and Kane, 1995).

During the Messinian Crisis, the Black Sea level dropped about 3,000 m compared with the present level due to the closing of the connection of the Mediterranean Sea with the Atlantic Ocean as a result of the African plate moving northwards and the uplifting of Gibraltar. Intense evaporation reduced the Mediterranean basin to only some hypersaline lakes. While in Dobrogea, the climate became extremely dry, some species retreated underground, finding here a chilly, humid shelter and abundant food, represented by the chemoautotrophic microbiota thriving due to the sulphide-rich waters that flooded the galleries at depths of about 200 m (Sarbu and Kane, 1995).

Much later, the Würm glaciations in Quaternary, when the level of the Black Sea dropped with about 100 to 110 m (Panin and Strechie, 2006), provided ideal conditions for new colonisation. Species such as Heteromurus nitidus and Cryptops anomalans are abundant in the cave, but are also found at the surface and in other caves.

In the table below are listed all the species of invertebrates identified in Movile Cave to date.

Species	Taxonomical affiliation	Reference
1.     Dendrocoelum obstinatum *	Plathelminthes, Tricladida, Dendrocoelidae	Stocchino et al., 2017
2.     Panagrolaimus c.f. thienemanni *	Aschelminthes, Nematoda, Panagrolaimidae	Muschiol et al., 2015
3.     Chronogaster troglodytes *	Aschelminthes, Nematoda, Chronogasteridae	Poinar and Sarbu, 1994
4.     Udonchus tenuicaudatus	Aschelminthes, Nematoda, Rhabdolaimidae	Muschiol et al., 2015
5.     Poikilolaimus sp.	Aschelminthes, Nematoda, Rhabditidae	Muschiol et al., 2015
6.     Monhystrella sp.	Aschelminthes, Nematoda, Monhysteridae	Muschiol et al., 2015
7.     Habrotrocha rosa	Aschelminthes, Rotatoria, Habrotrochidae	Claudia Ricci, pers. com.
8.     Habrotrocha bidens	Aschelminthes, Rotatoria, Habrotrochidae	Claudia Ricci, pers. com.
9.     Haemopis caeca *	Annelida, Hirudinea, Haemopidae	Manoleli et al., 1998
10. Allolobophora sp.*	Annelida, Oligochaeta, Lumbricidae	Dumnicka, E., pers. com.
11. Aelosoma hyalinum	Annelida, Aphanoneura, Aelosomatidae	Dumnicka, E., pers. com.
12. Aelosoma litorale	Annelida, Aphanoneura, Aelosomatidae	Dumnicka, E., pers. com.
13. Heleobia dobrogica *	Mollusca, Gastropoda, Moitessieriidae	Falniowski et al., 2008
14. Pseudocandona n.sp. *	Crustacea, Ostracoda, Cyprididae	Danielopol, pers. com.
15. Eucyclops subterraneus scythicus *	Crustacea, Copepoda, Cyclopidae	Plesa, 1989
16. Tropocyclops prasinus	Crustacea, Copepoda, Cyclopidae	Plesa, 1989
17. Parapseudoleptomesochra italica	Crustacea, Copepoda, Harpacticoida	Rouch, pers. com.
18. Pontoniphargus racovitzai *	Crustacea, Amphipoda, Niphargidae	Dancau, 1970
19. Niphargus dancaui *	Crustacea, Amphipoda, Niphargidae	Brad et al., 2015
20. Asellus aquaticus infernus *	Crustacea, Isopoda, Asellidae	Turk-Prevorčnik and Blejec, 1998
21. Caucasonethes n.sp.*	Crustacea, Isopoda, Trichioniscidae	Tăbăcaru, pers. com.
22. Haplophthalmus movilae *	Crustacea, Isopoda, Trichioniscidae	Gruia and Giurginca, 1998
23. Trachelipus troglobius *	Crustacea, Isopoda, Trachelipodidae	Tăbăcaru and Boghean, 1989
24. Armadillidium tabacarui *	Crustacea, Isopoda, Armadillidiidae	Gruia et al., 1994
25. Chthonius monicae *	Arachnida, Pseudoscorpiones, Chthoniidae	Boghean, 1989
26. Roncus dragobete *	Arachnida, Pseudoscorpiones, Neobisiidae	Ćurčić et al., 1993
27. Roncus ciobanmos *	Arachnida, Pseudoscorpiones, Neobisiidae	Ćurčić et al., 1993
28. Carniella brignolii	Arachnida, Araneae, Theridiidae	Georgescu, 1989
29. Leptyphantes constantinescui*	Arachnida, Araneae, Linyphiidae	Georgescu, 1989
30. Agraecina cristiani *	Arachnida, Araneae, Clubionidae	Georgescu, 1989
31. Nesticus n.sp. *	Arachnida, Araneae, Nesticidae	Georgescu, 1994
32. Hahnia caeca *	Arachnida, Araneae, Hahniidae	Georgescu and Sarbu, 1992
33. Dysdera crocata	Arachnida, Araneae, Dysderidae	Nae, pers. com.
34. Labidostoma motasi *	Arachnida, Acarina, Nicoletiellidae	Iavorschi, 1992
35. Geophilusalpinus	Chilopoda, Geophilomorpha, Geophilidae	Zapparoli, pers. com.
36. Clinopodes carithiacus	Chilopoda, Geophilomorpha, Geophilidae	Zapparoli, pers. com.
37. Cryptops anomalans	Chilopoda, Scolopendromorpha, Cryptopidae	Negrea, 1993
38.      Symphynella sp.	Chilopoda, Symphyla, Scolopendrellidae	Sheller, U., pers. com.
39.      Archiboreoiulus n.sp. *	Diplopoda, Julida, Julidae	Tăbăcaru, I., pers. com.
40.      Deuteraphorura movilae *	Insecta, Collembola, Onychiuridae	Gruia, 1989
41.      Onychiurus bogheani *	Insecta, Collembola, Onychiuridae	Gruia, 1989
42.      Heteromurus nitidus	Insecta, Collembola, Entomobryidae	Gruia, 1998-1999
43.      Oncopodura vioreli *	Insecta, Collembola, Cyphoderidae	Gruia, 1989
44.      Plusiocampa isterina *	Insecta, Diplura, Compodeidae	Conde, 1993
45.      Plusiocampa euxina *	Insecta, Diplura, Compodeidae	Conde, 1996
46.      Medon dobrogicus *	Insecta, Coleoptera, Staphyninidae	Decu and Georgescu, 1994
47.      Tychobythinus sulphydricus*	Insecta, Coleoptera, Staphyninidae, Pselaphinae	Poggi and Sarbu, 2013
48.      Decumarellus sarbui *	Insecta, Coleoptera, Staphyninidae, Pselaphinae	Poggi, 1994
49.      Bryaxis dolosus *	Insecta, Coleoptera, Staphyninidae, Pselaphinae	Poggi and Sarbu, 2013
50.      Clivina subterranea *	Insecta, Coleoptera, Clivinidae	Decu et al., 1994
51.      Nepa anophthalma *	Insecta, Hemiptera, Nepidae	Decu et al., 1994

This biocenosis, unusually rich and diverse for an underground one, is entirely based on primary production of organic matter that occurs in situ, by chemosynthesis.

The main group of primary producers are the sulphur oxidisers, both aerobic and facultatively anaerobic (Rohwerder et al., 2003). Sulphate-reducing bacteria were also evidenced, the sulphur cycle being complete and seemingly connected with the nitrogen cycle through denitrification linked to sulphur oxidation (Rohwerder et al., 2003; Kumaresan et al., 2014).

The second most important primary producers are methano- and methylotrophic bacteria, using as sole source of carbon and energy, CH₄ and C1-compounds such as methanol and methylated amines resulted from the degradation of the microbial biofilm, respectively (Rohwerder et al., 2003; Chen et al., 2009; Wischer et al., 2015).

Among the obligate methylated amine users present in the microbial biofilm Methylotenera mobilis dominates (Kumaresan et al., 2014). Other abundant methylotrophs are Methylobacterium extorquens and Methylovorus but also bacteria that were not known to grow methylotrophically such as Catellibacterium (98% identity to Catellibacterium caeni), Cupriavidus (99% identity to Cupriavidus necator), Porphyrobacter (99% identity to Porphyrobacter neustonensis) and Altererythrobacter (99% identity to Altererythrobacter epoxidivorans) (Wischer et al., 2015).

Movile Cave fungal community is also very well represented with the genera Aspergillus and Trichoderma being the most abundant and diverse. New species endemic for this environment (Aspergillus movilensis, A. europeus and A. dobrogensis) have been recently researched (Hubka et al., 2015; Hubka et al., 2016). Also of great abundance and variability in the cave is the genus Trichoderma. The association with the chemoautotrophic bacteria and archaea present in the microbial pellicles floating on the surface of the water seems to be of ecological importance, in consumption of the organic material produced chemoautotrophically as well as in dead cells degradation (Nováková et al., 2017).

Justification of Outstanding Universal Value

Movile Cave and the thermal sulphurous aquifer of South Dobrogea is an outstanding underground ecosystem, almost completely isolated from the surface, self-sustained due to in situ production of organic matter and energy. Its exceptionally rich and diverse biocenose (35 species of invertebrates out of 51 are endemic for this site) is entirely sustained by the chemolithotrophic bacteria, able to convert the toxic H₂S and CH₄ compounds from the sulphurous water into organic matter.

Criterion (viii): This criterion is met by the proposed site since it represents one of the few examples of speleonesis due to sulphidic acid corrosion of limestone along with carbonic corrosion.

The Messinian Crisis about 5.5 to 5.2 mya and the Würm glaciation, about 15.000 years ago (Sarbu and Kane, 1995) are mirrored by the composition of the communities of invertebrates living in the sulphurous ecosystem.

Criterion (ix): The sulphurous aquifer proposed is an excellent example of significant processes of adaptation to peculiar underground conditions that, even if apparently incompatible with life, are critical for the existence of a rich and diverse biocenosis formed from 51 species of invertebrates, from which 35 are endemic for this ecosystem. Some of these species clearly illustrate the capacity to adapt morphologically and physiologically to the peculiar conditions of this underground environment. They present the characteristics typical to troglo/stigobitic organisms, such as lack of eyes, depigmentation, elongated appendices and legs, type K reproductive strategy, metabolic rate reduction, longer life span.

Criterion (x): Movile Cave ecosystem represents an unique pool of biodiversity, gathering 51 species of invertebrates, both terrestrial and aquatic, of which 35 are endemic for Movile Cave or for the sulphidic aquifer associated.

The basis of the trophic web of this biocenose is represented by an exceptional microbial community, where sulphur oxidising and sulphate reducing bacteria, both aerobic and facultatively anaerobic, complete the sulphur cycle that is seemingly connected with the nitrogen cycle through denitrification linked to sulphur oxidation.

Statements of authenticity and/or integrity

The proposed site satisfies the condition of integrity as stipulated in paragraphs 87 and 88 of the Operational Guidelines meaning that:

It includes all the elements from which its outstanding value resides. The site consists of the ecosystem associated to the sulphurous aquifer of Mangalia, having as hot spot Movile Cave. Since the access into the cave is strictly regulated for protection reasons, glimpses of this system can be cached from both the surface sulphurous springs as well as from the springs discharging on the bottom of the sea at shallow depths (0 to – 25m) easy accessible by SCUBA diving and/or snorkelling.

The key element of the site, the condition of the very existence of the entire ecosystem is represented by the microbial biofilm. Underground, in the cave, this biofilm represents the site of primary production by chemosynthesis, the place sustaining the entire ecosystem providing energy and organic matter, food and habitat for the invertebrate species. At the exterior, in and nearby the sulphurous springs, but also underwater on the sea bottom, the microbial biofilm is spectacular.

For the underground sites where the thick microbial pellicles responsible for the primary production by chemosynthesis form, the so called Air Bells of Movile Cave, special care has been taken for protection. The rate of biofilm formation was monitored in order for specific, efficient management measures to be taken and a set of regulations has been elaborated referring to this part of the cave. As a consequence, the chemosynthesis processes are still undisturbed. The experts from the Group for Underwater and Speleological Exploration (GESS), both as scientists and former custodians are confident that the underground environment can be considered still unspoiled.

The surface sulphurous springs are yet unspoiled, even if very accessible.

The Movile Cave has been protected since the very beginning (discovered in 1986) being kept isolated from the surface by an ingenious closing system represented by three gates, the access has been strictly restricted and thus both its territorial integrity and the biocenoses integrity are still intact. The monitoring activities, performed periodically by the specialists of the Group for Underwater and Speleological Exploration (GESS), has revealed the conservation of the site in terms of species inventory and number of individuals from each species. During these activities, endemic species of invertebrates of the underground ecosystem as well as the microbial biofilm represented the key elements of monitoring.

The Movile Cave and the entire thermal sulphurous aquifer of South Dobrogea are protected by the national legislation in the field of territorial development and nature protection. Moreover, the site, its buffer and the marine and costal area in connection with the thermal sulphurous aquifer of South Dobrogea are inscribed in several Natura2000 nature protected sites such as ROSCI0114 Mlaștina Hergheliei - Obanul Mare și Peștera Movile, ROSPA0066 Limanu - Herghelia, ROSCI0094 Izvoarele sulfuroase submarine de la Mangalia, ROSCI0281 Cap Aurora and ROSPA0076 Marea Neagră.

The specific bio-physical process that makes the site so unique, the chemosynthesis, is virtually intact due to the protection measures taken since the discovery of the cave to present.

Since periodically the chemical parameters of the water are monitored (pH, T°C, dissolved O₂ and H₂S) we trustfully conclude that to date, the ecosystem has not been contaminated with waste water and/or any other contaminants that might get underground from the households nearby and/or from the cultivated fields above.

In the sense of paragraph 94 from the Operational Guidelines, we estimate that the site meets the condition of integrity since it has a significant size, being spread on several localities and in the Black Sea. As relevant elements, beside Movile Cave which is the hot spot of the property, it contains the entire underground ecosystem associated with the sulphurous aquifer of Mangalia, more precisely the sulphurous lakes Kara Oban and Mlaștina Hergheliei (Hergheliei Swamp) and all the terrestrial sulphurous springs located in Mangalia and/or around the city together with the underwater sulphurous springs on the bottom of the Black Sea, in the region of Mangalia these latter representing the Natura2000 site ROSCI0094 Izvoarele Sulfuroase Submarine de la Mangalia (Mangalia Sulphurous Undersea Springs).

Comparison with other similar properties

To date, there are no other examples representing significant on-going ecological and biological processes based on chemosynthesis inscribed on the World Heritage List.

Nevertheless, several caves hosting chemosynthesis within sulphidic aquifers are known from across the world. Among these, some of the most studied are Frasassi Caves Complex (Italy) and Melissotrypa (Greece) in Europe, Lower Kane Cave (Wyoming) in the USA, Villa Luz Cave in Mexico and Ayyalon Cave in Israel (Hillebrand-Voiculescu, in press). The most similar to Movile Cave in terms of isolation from the surface is Ayyalon Cave, all the other caves having contact with the surface environment and consequently significant input of exogenous organic matter. In contrast to other hypogenic caves, only the Movile and Ayyalon caves were proven to be completely isolated from the surface and hosting ecosystems entirely based on chemosynthesis. The Movile Cave was first of these two sites to be discovered. By the time of its discovery, the only known chemosynthesis based ecosystems were those associated to the hydrothermal vents, on the bottom of the oceans, at depths of thousands of meters. Thus, Movile Cave ecosystem has been the first discovered terrestrial ecosystem completely depending on the in situ production of organic matter and energy by chemosynthesis.

As regards the Ayyalon cave biocenose, the published data are still scarce. According to the existing available information it consists of only eight species (four stygobiont and four troglobitic), six of them being endemic for this cave (Por et al., 2013) as compared to Movile cave whose biota is much richer and diverse (51 species), presents a higher degree of endemicity (35 endemic species) being thus absolutely unique.

Movile cave is also unique with respect to its integration into a much broader ecosystem that is associated to the thermal sulphurous aquifer of South Dobrogea, and which area is estimated to be more than 50 km². This means that the known aquifer is surrounded by a large area of land whose geographical boundaries are not known precisely, with a supposed extension based on an unpublished isotopic data base.