Diversity and Ecology of Periphytonic Algae in the Arys River Basin, Kazakhstan

No one information about algal community diversity from the Arys River basin was before this study. The first data about algal and cyanobacteria species diversity was represented for the Arys River basin and compared it to freshwater algae patterns of the related mountain regions. Altogether 82 species were found in 28 samples of phytoperiphyton on 13 sampling stations of the Arys River and its tributaries. Diatoms prevail in studied algal flora. Bioindication characterize the Arys River waters as temperate, moderately oxygenated, fresh, neutral water affected by a low to moderate level of organic pollution, Class II-III of water quality. The pattern of algae and cyanobacteria diversity distribution depends on altitude and local climatic and environmental conditions. Bacillariophyta species was richest in high mountain habitats, green algae, cyanobacteria and charophytes avoid high mountain habitats and have negative correlation with altitude. These results can be used as indicator of environmental changes in the mountainous areas. Three floristic groups were recognized in the studied river communities corresponding to the upper, middle and lower parts of the watershed. The general trend is an increase of species diversity from lowland areas to the high mountains. Our analysis revealed the altitude of habitat and related climatic factors control over the major diversity patterns in the Arys River basin, the second largest river in Southern Kazakhstan.