Investigation presents the assessment of species composition and structure of microbiota communities in the Otap Head Cave. Species were identified using standard approaches and cultivation methods. The abundance of algae and cyanobacteria was estimated applying 5-point Brown- Blank scale. Biodiversity of biofouling communities was revealed. Cyanobacteria were the dominant group of phototrophs colonizing cave wall and water streams. The most frequently documented cyanobacteria were species from genera Chroococcus, Gloeocapsa, Oscillatoria, Phormidium. Among micromycetes prevailed Ascomycetes (genera Aspergillus, Penicillum, Trichoderma). The development of so-called lamp flora around artificial lights was not observed. The presence of sulfate-reducing and sulfur-oxidizing bacteria was detected. It can indicate that a small circulation of sulfur occurs in cave at the present time.

Unique natural objects, such as the caves of the Gobustan National Historical and Artistic Preserve, are also of great cultural and historical value due to rock art and sites of ancient people. A favorable microclimate makes these habitats convenient for colonization by microbiota, including phototrophs. In arid regions with intense seasonal fluctuations of microclimatic parameters, the conditions for survival are the least favorable; therefore, it becomes especially important to determine the composition of communities that are the most adapted to specific conditions. This work aimed to identify the biodiversity of communities of caves and grottoes of the Gobustan Reserve. The studies were carried out in July 2019. Samples were analyzed for cyanobacteria and algae by microscopy and cultivation methods, microfungi were isolated by soil dilution, and the fouling glass method was also used. In total, 29 taxa of cyanobacteria and algae, 18 taxa of fungi, and 3 species of mosses were identified. The studied habitats were dominated by the algae Chlorella vulgaris, Aphanocapsa sp., and Stichococcus bacillaris; the subdominants were Jaaginema subtilissimum, Leptolyngbya tenuis, Chlorococcum minutum, and Humidophila contenta. Microfungi had the highest occurrence of Aspergillus niger, Aureobasidium pullulans, Alternaria alternata, and Talaromyces ruber. It was noted that cyanobacteria dominated in morphologically differentiated biofilms and green algae on the rocks. The greatest number of microfungi was found in the aphotic zone and bryophyte tufts. The dominance of green algae is atypical for most caves of other regions and may be associated with intense lighting of habitats. The absence of protonema is a consequence of the aridity and low moisture content of the substrates.

Investigation presents the multiyear assessment of biodiversity and development features of phototrophic communities from hypogean habitats. Caves exploitation as a tourist sites leads to anthropogenic transformation of subterranean ecosystems and formation of new communities named lampenflora. An example is given by the Ahshtyrskaya Cave (Sochi, Russia), which was equipped in 2000. The air temperature in the cave was 9-18 °C, humidity average 60-80%, the content of 222Rn 250-550 Bk/m3. Species identification was performed using standard approaches and cultivation methods. Cluster analysis was used to estimate similarity of communities in different cave zones. Biodiversity of phototrophs was revealed in entrance zone and zone of artificial light in 2017 - 2019. Species Microcystis pulverea, Scytonema drilosiphon, Chlorella vulgaris, Eucladium verticillatum predominated in communities of abovementioned zones. Considering the entrance zone communities as climax ones, comparison them with lampenflora can help to determine the speed and direction of succession. As a result of cluster analysis, it was established that species composition of lampenflora is most close to the entrance zone in case of maximum illuminated area. Thus, the succession of lampenflora depends on the intensity of illumination and tends to the species composition of the entrance zone communities.

The article discusses the ecological significance of the phototrophic communities developing in entrance zone of grotto type caves as ecotones and refugiums. Species intrazonality and the dependence of cave species composition on geographic location were considered. The aim of present study was to identify similar caves of different regions based on the species composition of phototrophic communities using own data and data from literature. The empiric basis for investigation was present by phototropic species lists of own studies conducted by standard methods for phototropic species identification, as well as species lists from literature. The most frequently encountered phototrophs were species Chroococcus minutus and Chlorella vulgaris. Their occurrence in all the studied caves was revealed based on the taxonomic analysis. Thus, the intrazonal nature of the flora developed in grotto type caves is partially confirmed. Cluster analysis applying Euclidean distance was used to estimate similarity of the phototrophic communities developed in grotto caves of various genesis. Four clusters were identified: cretaceous caves of the Voronezh region; limestone grottoes of Ukraine and Abkhazia; monastic cells of Moldova and Ukraine; caves of Italy and Hungary. The dependence of the phototrophs biodiversity on the composition of the rocks and the genesis of the cavities was established. The geographical trend of photosynthetic species distribution in the grotto type caves was revealed.