LATE QUATERNARY CLIMATE HISTORY OF COASTAL ANTARCTIC ENVIRONMENTS: A MULTI-PROXY APPROACH (LAQUAN) (EV/01)

• Main Authors: Vyverman, Wim, Wilmotte, Annick, Verleyen, Elie, Schmoker, Claire, Sabbe, Koen, Cousin, Sylvie, De Groot, Lena, Waleron, Krzysztof, Balthasart, Pierre, Taton, Arnaud, Lemaire, Cedric
• Other Authors: CIP - Centre d'Ingénierie des Protéines - ULiège
• Format: Report
• Language: English
• Published: Belgian Science Policy Office 2007
• Subjects: polar science; Paleoecology; Antarctica; fossil DNA; climate change; lake sediments; Life sciences; Environmental sciences & ecology; Aquatic sciences & oceanology; Microbiology; Sciences du vivant; Sciences de l’environnement & écologie; Sciences aquatiques & océanologie; Microbiologie; Antarctic; East Antarctica; Larsemann Hills; Single Lake; Heart Lake; Antarc*
• Online Access: https://orbi.uliege.be/handle/2268/227623; https://orbi.uliege.be/bitstream/2268/227623/1/rappEV01_enfinal.pdf

Novel biological proxies and inference models were developed to reconstruct past environmental changes in Antarctic ice-free regions. Reference datasets of cyanobacterial sequences, diatoms and pigments were constructed in order to study the present diversity and distribution of biota in benthic microbial mats from Antarctic lakes. These datasets were subsequently used for comparison between living and fossil floras or to develop inference models to quantitatively reconstruct past environmental changes in East Antarctica. Paleolimnological analyses and application of the models revealed the history of late Quaternary variation in climate, ultraviolet (UV) radiation, and relative sea-level in the Larsemann Hills. The study of modern cyanobacterial diversity showed that each lake is quite unique in terms of diversity. Every single lake studied resulted in the discovery of new Operational Taxonomic Units (OTUs), which suggests that there is a lot more diversity to discover. The majority of the genotypes are restricted to Antarctica and sometimes, even present only in one sample, which hints to the existence of endemic cyanobacteria. A taxonomic inventory of the diatom flora from the Larsemann Hills similarly revealed that Antarctic endemics account for about 40 % of all freshwater and brackish taxa. Fossil cyanobacterial sequences were found in layers of up to 9000 years old. The validation of fossil sequences of Progress and Heart Lake cores by both laboratories allowed us to assess that a majority of cyanobacterial sequences found in sedimentary core layers were really from fossil organisms. Comparison between the modern and fossil diversity revealed that most fossil sequences were also present in modern samples. The main problems encountered were related to the presence of good-quality bacterial DNA that act as competitor of fossil DNA during PCR, downcore degradation of fossil DNA, and the selective, group-specific resistance of cyanobacterial DNA to degradation. The main paleoenvironment-related results can be ...