Survey of the biotic Community and environment of the saline Lake Chany eomplex in Western Siberia based on NOAA images

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We evaluated the seasonal changes in the lake area and surrounding vegetation of the Lake Chany complex, located in Western Siveria, using NOAA images of the ice-free periods from 1999 to 2003 and compared the NOAA images with the data from ground truth. The Normalized Difference Vegetation Index (NDVI), which is calculated by two channels, red (CH1) and infrared (CH2), of the NOAA AVHRR data, can provide information on the open water area of the land surface as well as temporal changes in vegetation distribution. The maximum lake area was observed in early May and the lake area decreased until late July and then increase until early October. Compared with the ground truth data, the areas undergoing seasonal fluctuations in the NOAA images corresponded to vast stands of reed vegetation. Although interannual differences in the seasonal change in lake area are not great for the whole lake complex, the isolated Yudindkii Pool shows large interannual differences, suggesting that monitoring this area in the NOAA images will be useful for estimating the interannual fluctuations in the southwestern Siberian environment. In this study we also investigated spatial differences in water quality and food web structure in different parts of the lake complex. We measured carbon, nitrogen and sulfur stable isotope ratios of zooplankton, benthic animals, particulate organic matter (POM, composed mainly of phytoplankton) and sediment organic matter (SOM). The results showed that the carbon, nitrogen and sulfur stable isotope ratios of organisms, POM and SOM increased with distance from the estuary into the innermost part of the lake complex with increasing salinity of the lake water. The results also showed a spatial separation of planktonic food webs in the Lake Chany complex along an environmental gradient.