SULFUR AND CARBON CYCLES IN PLANKTON AND MICROBIAL MATS OF A STRATIFIED LAKE IN KARA-KALPAK REPUBLIC

Species composition of photosynthesizing microorganisms and intensity of organic matter production were studied both in water column and in microbial mats of a small stratified saltwater lake with 24 mg H2S/lit er near the bottom. The lake is situated at the border of the Kyzyl Ku m desert in a zone of intense rice cultivation. Maximum depth of the l ake is 1.75 m. Water mineralization is 18 g/liter at the surface and 2 8 g/liter at the bottom. Anaerobic zone boundary is observed between 0 .75 and 1.0 m and coincides with the halocline. In the water column at a depth of 1.25 m development of purple and green bacteria was observ ed. The above zone was also distinguished by development of unicellula r and filamentous cyanobacteria and diatoms. The total photosynthesis productivity in the water column was 0.8 g C/(m(2).day). Anoxygenic ph otosynthesis amounted to 20% of this value.