Mud volcanoes are one of unique natural phenomena widely spread around the world. They can be found in Crimea, including the Bulganak sopochnoe field – the largest cluster of active mud volcanoes on the peninsula (45°25′29.04″N, 36°27′51.64″E). Study of mud volcano microalgae in Crimea, as well as in other regions of Russia, has not been conducted so far. Therefore, scientific interest is caused by need and urgency of the study of these volcanoes. First data on microalgae species composition of active mud volcanoes are presented in this article. Samples collected by O. Yu. Eremin (03.08.2012 and 13.04.2013) in the upper 2–3-cm layer of suspension and in surface water were investigated. The ranges of salinity and water temperature were 27–32 g per L and +28…+31 °C, respectively. Microalgae species composition was determined in water preparations using Axioskop 40 (Carl Zeiss) light microscope at magnification of 10×40 with software AxioVision Rel. 4.6. Totally 16 taxa were found: Cyanobacteria (1), Dinophyta (2), Bacillariophyta (6), and Euglenophyta (7). Of these, cyanobacteria Chamaecalyx swirenkoi (Schirshov) Komárek et Anagnostidis, 1986 was found by us in the mud volcano in August 2012. Pennate species of diatoms were also identified – single living (of genera Cylindrotheca (Ehrenberg) Reimann & J. C. Lewin, Lyrella Karajeva, and Nitzschia Hassall) and colonial species (of genera Berkeleya Greville and Pseudo-nitzschia H. Peragallo). The brackish-water, benthic, boreal-tropical species Nitzschia thermaloides Hustedt was recorded for the algal flora of Crimea, the Black Sea, and the Sea of Azov for the first time. Euglenophytes were also found in the samples – 5 species of the genus Trachelomonas Ehrenberg and 2 species of the genus Strombomonas Deflandre. Of all the species found in the mud volcano ecotope, 7 species are common for the Black Sea, and 9 species, including 3 euglenophytes, are common for the Sea of Azov. It is shown that by characteristics of halobility, species found in the mud volcano belong to freshwater complex (53 %), with a significant share of marine (27 %) and brackish-water (20 %) species. Of the phytogeographic flora elements, boreal species make up 33 %, boreal-tropical – 47 %, and cosmopolites – 20 %. Three species of potentially toxic algae are recorded: diatom Pseudo-nitzschia prolongatoides (Hasle) Hasle, 1993, as well as dinophytes Prorocentrum lima (Ehrenberg) Dodge, 1975 and Alexandrium tamiyavanichii Balech, 1994. The last species is marine, boreal-tropical, and new to the algology of Crimea, the Black Sea, and the Sea of Azov. In the article, own and literary data on morphology, ecology, and phytogeography of species, as well as on their general distribution in different waterbodies of the world, are also presented. Some microalgae species are indicators of saprobity; they are able to participate in purification of water from organic substances. Photos of mud volcanoes and micrographs of some species are presented.
Mud-volcanic deposits of methane gas hydrates in the Black Sea
