Seminar

Global warming will accelerate glacial melting, leading to the expansion of lake surface area and the increase of lake level in Tibetan Plateau (TP).  The pristine sediment which is exposed to the air previously in the nearshore will be submersed, inducing the changes in biogeochemical processes in lake water bodies and sediment. The Lake Ranwu, located in the southeast of the TP, is a glacial-fed lake highly sensitive to climate change. This study systematically investigated the chemical properties, microbial diversity and compositions, and functional genes in sediment along the littoral zone of Lake Ranwu. Results showed that the chemical properties had various distribution across the profile, while aerobic microbes had a competitive advantage in the nearshore sediment, and gradually replaced by anaerobic microorganisms towards offshore zone. The relative abundance of functional genes indicated that the metabolisms of nitrogen, sulfur, and carbon become more active in littoral sediment towards offshore areas. A Partial Least-Squares Path Model was constructed to evaluate the direct and indirect effects of climate change on these metabolisms. The modeling results suggested that climate change had direct effect on the primary productivity firstly, which further influenced microbial diversity and regulated microbial species. Consequently, nitrogen, sulfur, and carbon metabolisms would be modulated. Specifically, ammonium oxidizers were the major group that influenced nitrogen metabolism, while nitrogen metabolism was the primary factor that influenced sulfur metabolism. The predominant factor that influenced carbon metabolism was microbial diversity.

Additional information: Ms. LU Meiqing, u3005778@connect.hku.hk