[Total number and biomass of microorganisms in the depths of the Black Sea].

The total number and biomass of microorganisms, as well as the ratio between their main morphological forms, were determined by capillary microscopy in 22 water samples taken at various depths from the surface to 1500 m in the eastern part of the Black Sea. The total number of microorganisms was several times higher at depths over 150 m in the hydrogen sulfide zone than in the oxygen zone (0--150 m), whereas the biomass was greater by an order of magnitude. The number of microorganisms varied within a range of 1.4--12.4X10(3) cells/ml in the oxygen zone and 3.8--34.9X10(3) cells/ml in the hydrogen sulfide zone, whereas the biomass was 0.9--6.9 mg/m3 and 10.8--55.6 mg/m3, respectively. The bulk of the microbial biomass in the hydrogen sulfide zone was constituted by peculiar filamentous forms described for the first time by Lebedeva (1953, 1963) and, apparently, participating in sulfur turnover.