Biomarker records of D5-6 columns in the eastern Antarctic Peninsula waters: responses of planktonic communities and bio-pump structures to sea ice global warming in the past centenary

• Main Authors: Dan, Yang, Haisheng, Zhang, Zhengbing, Han, Xibin, Han, Yicheng, Zhang, Wensheng, Chen, Qian, Liu, Jianming, Pan, Gaojing, Fan, Fengfeng, Le, Bing, Lu, Jing, Huang
• Format: Article in Journal/Newspaper
• Language: English
• Published: Polar Research Institute of China - PRIC 2021
• Subjects: Atmosphere; Cryosphere; Oceans; Antarctic; The Antarctic; Antarctic Peninsula; Advances in Polar Science; Antarc*; ice algae; Polar Science; Sea ice
• Online Access: http://library.arcticportal.org/2742/; http://library.arcticportal.org/2742/1/A2101003.pdf

Molecular biomarkers (e.g., isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) and proxies, such as di-unsaturated to tri-unsaturated highly branched isoprenoids (D/T) ratio, total organic carbon, δ13C and ice-rafted debris (IRD)) were used to reconstruct the dominant phytoplankton (diatoms, dinoflagellates and coccolithophores), phytoplankton and zooplankton productivity, biological pump structure, and archaea assemblage (Euryarchaeota and Crenarchaeota) from a marine sediment core (D5-6) dated with 210Pb (1922–2012). We characterized the environmental response to sea ice variations/global warming off the eastern Antarctic Peninsula. The results showed that (1) the biomarkers brassicasterol (average = 519.79 ng·g−1), dinosterol (average = 129.68 ng·g−1) and C37 alkenones (average = 40.53 ng·g−1) reconstructed phytoplankton (average = 690.00 ng·g−1) and zooplankton (cholesterol average = 669.25 ng·g−1) productivity. The relative contribution to productivity by different phytoplankton groups was diatoms > dinoflagellates > coccolithophores. This is consistent with field surveys showing that diatoms dominate the phytoplankton in waters adjacent to the Antarctic Peninsula. (2) The relative abundances of different highly branched isoprenoids reflected the contributions of sea ice algae and open water phytoplankton (D/T = 1.2–30.15). Phytoplankton productivity and sea ice showed a good linear relationship with a negative correlation, indicating that more open water during periods of warming and reduced sea ice cover led to an enhanced biological pump. (3) Over the past 100 years, phytoplankton productivity and zooplankton biomass increased. This trend was particularly evident in the last 50 years, corresponding to increased global warming, and showed a negative correlation with IRD and D/T. This suggests that with decreasing sea ice coverage in a warming climate, diatom biomass greatly increased. Coccolithophore/diatom values and the ratio of C37 alkenones to total phytoplankton productivity decreased, ...