Mycobiota of the pelagic zone of Odessa region in the northwestern Black Sea
Authors:   A.O. Kovalevsky Institute of Biology of the Southern Seas, Russian Academy of Sciences (Sevastopol, Russian Federation), Kopytina Nadezda I. 
Published: January 2021

Mycobiota of the marine area of Odessa region was studied (30°70′00′′-31°00′00′′N, 46°23′00′′-46°60′00′′E) (See Fig. 1). Hydrological and hydrochemical regimes of the marine area of Odessa region in the northwestern Black Sea are affected by the discharge of the Dnieper (93.4%) and the Southern Bug (5.7%) rivers, the permanent anthropogenic discharges of the cities of Odessa, Chernomorsk (Ilyichyovsk), Yuzhnyi and their ports, shipping, dredging, and the open sea. The aim of this work was to study the species composition, the number of colony forming units (CFU) and the dynamics of the spatiotemporal distribution of reared microfungi as a function of abiotic factors and the trophic level of seawater in this area. Water samples were taken in summer and autumn 2008-2012 in the surface (1 m depth) and bottom (7-24 m depth) layers. The samples were taken, at least, in three replicates. The results of processing 258 samples from 22 stations were analyzed. The effects of environmental factors (water temperature, salinity, dissolved oxygen, five-day biochemical oxygen demand, petroleum hydrocarbons, dissolved metals Cu, Zn, Ni, Cd and suspended particulate matter) were studied in 140 samples (See Table 1). Micromycetes were isolated on Czapek’s medium prepared in sea water. 1 ml of sample water was added to a Petri dish and filled with medium cooled to approximately 36-40 °C. To suppress the growth of bacteria, 0.03% chloramphenicol was added to the medium (by volume of the medium). Cultivation was carried out at a temperature of 18-20 °С for 2-8 weeks. Micromycetes were identified by morphological and cultural characteristics according to Vera Bilay and Eleonora Koval’ (1988) and GS De Hooh ea tl. (2000). Nomenclature, and taxonomy of fungi correspond to The Index Fungorum database. The ecological analysis of mycocomplexes was carried out according to: species composition, the number of species in complexes, frequency of occurrence of a species and the number of colony-forming units (CFU / L). In this research, 50 fungal species of 19 genera, 14 families, 9 orders, 4 classes of the division Ascomycota were revealed. Fungal taxa from Odessa region were grouped into families. The family Aspergillaceae included the genera Aspergillus, Penicillium and Talaromyces (27 species); the family Pleosporaceae included the genera Alternaria and Stemphylium (8); and there were 3 species of the genus Cladosporium from the family Cladosporiaceae. In total, 76.0% of species found were from the three families (See Table 2). Using Average Taxonomic Distinctness index, AvTD (Δ+), and Variation in Taxonomic Distinctness index, VarTD (Λ+), features of the taxonomic diversity of mycocomplexes were revealed. These indices were calculated from a matrix of micromycete species from the region under study combined with the fungi list (master list, 219 species) of the Black Sea pelagic zone. In the analysis, the taxonomy levels from Species to Kingdom were included. For the indices Δ+ and Λ+, 95% probability funnel graphs were plotted, and their mean expected values were calculated for mycobiota of the region under study and for mycocomplexes from each station. It was found out that the mean expected values of the index Δ+ for mycobiota of the marine area of Odessa region and the stations are considerably lower, and index Λ+ values are higher than those for the sea as a whole (See Fig. 2 and 3). According to literature sources, no significant seasonal and inter-annual changes in the trophic status of the region occurred in 1992-2010. It was transitional between mesotrophic and eutrophic. The long-term mean TRIX value was 5.3 (4-5: medium trophic level; 5-6: high trophic level and poor water quality). In the species composition and numerical structure of mycocomplexes of the mesotrophic and eutrophic zones, no significant differences were detected. Over the entire period of this research, a relatively uniform distribution of the mean abundance of fungi over the area and depth was noted (See Table 3). No significant correlation was found between abiotic parameters under study and micromycete abundance over the horizons, seasons, sampling dates, location of stations, as well as mesotrophic and eutrophic zones. In the region, 44% of fungi-indicators of different kinds of pollution were registered. In the areas of stormwater runoff and wastewater treatment plant discharges, the indicator value (IndVal) was the largest for melanin-containing fungi Cladosporium cladosporioides (28.3%), Alternaria alternata (17.5%), and Aspergillus niger (12.3%), which are resistant to several adverse environmental factors. In the eutrophic zone, large values of the indices were found in Aspergillus clavatus (21,2%), Penicillium expansum (17,7%), Penicillium citrinum (16,1%), Al. tenuissima (12,5%), and in A. fumigatus (60%), Al. alternata (40%) and A. niger (35,7%) in places of local oil pollution. It is established that in the entire marine area of Odessa region, the formed mycocomplexes have a high similarity in species and numerical structure, and therefore, they can be considered as a single community.