EGU21-1565, updated on 03 Mar 2021
https://doi.org/10.5194/egusphere-egu21-1565
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Ecological impacts caused by the alternance of wet/dry episodes occurred in the last 2,000 years in southern Tibetan Plateau: A paleoecological record from Lake Nam Co

Paula Galindo1, Peter Frenzel2, Sten Anslan3, Sonja Rigterink1, Julieta Massaferro4, Wengang Kang1, Bernd Wuennemann5, Liseth Pérez1, Philipp Hoelzmann5, Nicole Börner1, Anja Schwarz1, Ping Peng6, Liping Zhu6, and Antje Schwalb1
Paula Galindo et al.
  • 1Institute of Geosystems and Bioindication, Technische Universität Braunschweig, Braunschweig, 38106, Germany (p.echeverria-galindo@tu-braunschweig.de, s.rigterink@tu-braunschweig.de, wengang.kang@tu-braunschweig.de, l.perez@tu-braunschweig.de, nicole.boer
  • 2Institute of Earth Sciences, Friedrich-Schiller-Universität, Jena, 07749, Germany (peter.frenzel@uni-jena.de)
  • 3Zoological Institute, Technische Universität Braunschweig, Braunschweig, 38106, Germany (s.anslan@tu-braunschweig.de)
  • 4Institute of Geographical Sciences, Physical Geography, Freie Universität Berlin, 12249, Berlin, Germany (philipp.hoelzmann@fu-berlin.de, wuenne@zedat.fu-berlin.de)
  • 5CENAC-National Park “Nahuel Huapi” (PNNH), National Scientific and Technical Research Council of Argentina (CONICET), Bariloche, Argentina (jmassaferro@comahue-conicet.gob.ar)
  • 6Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, P.R. China (pengping@itpcas.ac.cn, lpzhu@itpcas.ac.cn)

High altitudinal aquatic ecosystems are subject to environmental change due to global warming and increasing solar radiation. The Nam Co catchment is part of the highest and largest alpine plateau on Earth, where the effects of climate change are expressed stronger than the global average. Thus, this area has experienced rapid changes in biodiversity. Fluctuations between wetter and drier periods during the last 2,000 calibrated (cal.) years were detected. These changes may alter the dynamics in ecosystems and therefore their resilience to climate change.

A ~65 cm sediment record from Nam Co spanning the late Holocene, was analyzed to evaluate the assemblage composition of three of the most abundant and diverse benthic taxa (Arcellinidae, Ostracoda and Chironomidae) and the diverse family of small bivalves (Sphaeriidae). In general, the presence of the bivalve Pisidium stewarti, together with a high abundance of black-coated ostracod shells, and high Ca/Ti and Zr/Rb ratios correspond to the driest period (~ 1,000 - 1,860 cal. years BP) detected in our sediment record. For the last 256 cal. years, higher lake levels were inferred from aquatic fauna composition and geochemical analysis (XRF and XRD) suggesting a more humid environment. This period was characterized by higher temperatures and a higher input of organic matter. Species not previously reported for Lake Nam Co such as Arcellinida species, the ostracod Ilyocypris angulata, several chironomid species, and the bivalve P. stewarti, were observed. These new records, as well as the detection of varieties in morphological structures (e.g. spines, aggregate material, valve ornamentations, etc.) highlight the probable existence of cryptic species in the ecosystem, which is an important factor to take into account for biodiversity evaluation and paleoenvironmental inferences, due to potential misleading ecological interpretation.

Therefore, emphasis should be placed on combining ecology, morphology and DNA analysis to corroborate the taxonomy of species already described, and determine the accurate richness and distribution of the species in an environment where endemism is expected. This is essential in order to evaluate possible losses or gains in terms of diversity that climate change may exert on aquatic ecosystems in the future.

How to cite: Galindo, P., Frenzel, P., Anslan, S., Rigterink, S., Massaferro, J., Kang, W., Wuennemann, B., Pérez, L., Hoelzmann, P., Börner, N., Schwarz, A., Peng, P., Zhu, L., and Schwalb, A.: Ecological impacts caused by the alternance of wet/dry episodes occurred in the last 2,000 years in southern Tibetan Plateau: A paleoecological record from Lake Nam Co, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1565, https://doi.org/10.5194/egusphere-egu21-1565, 2021.