Аннотация:Abstract: Results are presented of an investigation of species composition, structure, andproductivity of phototrophic communities from Anyashka Cave, Caucasus. The dominant group ofphototrophs colonizing cave substrates were cyanobacteria, and the most frequently encounteredcyanobacteria were species from the genera Chroococcus and Leptolyngbya. Differences betweenspecies composition in zones relative to the water flow were revealed. Measurement of gross primaryproduction (GPP) in the daytime during the spring–summer period enabled collection of data onthe maximum productivity of communities. Estimates of the GPP of phototrophic communitiesdeveloping on different substrates vary from −0.1503 gC/m2h to −0.0109 gC/m2h. The highest GPPwas recognized in communities with a predominance of Pteridophyte and Bryophyte species onwater-splashed clay. However, similar communities developing on other substrates (limestone, clayon limestone) displayed lower GPP. Thus, significant impact of substrate type on the communities’productivity was demonstrated. Net carbon flux values showed that at peak productivity not allmeasurement sites acted as carbon dioxide sinks; some sites functioned as carbon dioxide sources.