We propose to reconstruct the water quality and hydrological variability of the past approximately 2000 years with decadal resolution using diatom species assemblages from about 1m-long sediment cores from Nam Co. In order to characterize the ecology of currently living diatoms, seasonal sampling will be carried out in (1) incoming streams in order to detect potential sources for eutrophication affecting the diatom population, and (2) sediment traps to characterize seasonal changes in diatom assemblages and changes of productivity in the lake measured by chlorophyll-a. This will help using integrate monitoring data to (3) detect the main drivers of diatom succession and clarify if diatoms identified in modern samples reflect climate change via water-budget changes as suggested by Wang et al. (2011), or rather land-use changes and atmospheric Nitrogen deposition increasing autochthonous production (Lami et al., 2010; Liu et al., 2015). By analysing modern diatom assemblages from lakes along an altitudinal gradient in the Nam Co catchment, Project W2 will further closely collaborate with P1 to detect ecotones in aquatic ecosystems (Antinoiades et al., 2014), a requirement to understand structures of ecosystem change and predict potential biodiversity losses.
Project W2 (and W3) will thus be used to test models of hydrological change (W1) and sediment deposition into the lake (S-topics) for the past and calibrate them for predicitions of future change. The assessment of future hydrological and mass balance changes as well as ecosystem reactions is one of the keys to develop sustainable mitigation and environmental protection strategies.
Chinese partners will focus on monitoring of the seasonal and annual phyto- and zooplankton cycle in Nam Co. This will substantially contribute to understanding the limnology of Nam Co and detect current climatic and potential anthropogenic changes. Sequential and integral sediment traps are available at Nam Co and continuously operated by our Chinese partners. Futhermore, toxic assessing of heavy metals (S2) will help to detect a possible anthropogenic influence on water quality.
Prof. Dr. Antje Schwalb, TU Braunschweig
Prof. Dr. Miguel Vences, TU Braunschweig
Prof. Dr. Patrick Rioual, IGG CAS