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

我们利用1999年至2003年无冰期的NOAA图像评估了位于西维利亚西部的Chany湖复合体的湖泊面积和周围植被的季节变化，并将NOAA图像与地面实况数据进行了比较。归一化植被指数(NDVI)是由NOAA AVHRR数据的红(CH1)和红外线(CH2)两个通道计算的，它可以提供陆地表面开阔水域面积的信息以及植被分布的时间变化。湖泊面积在5月上旬达到最大值，7月下旬湖泊面积减少，10月上旬湖泊面积增加。与地面实况数据相比，NOAA图像中发生季节性波动的区域对应于大片的芦苇植被。尽管整个湖泊面积季节变化的年际差异不大，但孤立的尤丁基池显示出很大的年际差异，这表明在NOAA图像上对该地区进行监测将有助于估计西伯利亚西南部环境的年际波动。在这项研究中，我们还调查了湖泊复合体不同部分的水质和食物网络结构的空间差异。测定了浮游动物、底栖动物、颗粒有机质(POM，主要由浮游植物组成)和沉积物有机质(SOM)的碳、氮、硫稳定同位素比值。结果表明，随着湖水盐度的升高，生物碳、氮、硫稳定同位素比值、POM和SOM随河口向湖泊复合体最深处的距离增大而增大。研究结果还表明，在查尼湖复合体中，浮游食物网沿环境梯度存在空间分离。

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.