Marine diatoms in ice cores from the Antarctic Peninsula and Ellsworth Land, Antarctica – species diversity and regional variability

Abstract

Abstract. The presence of marine microfossils (diatoms) in glacier ice and ice cores has been documented from numerous sites in Antarctica, Greenland, as well as from sites in the Andes and the Altai mountains, and attributed to entrainment and transport by winds. However, their presence and diversity in snow and ice, especially in polar regions, is not well documented and still poorly understood. Here we present the first data to resolve the regional and temporal distribution of diatoms in ice cores, spanning a 20 year period across four sites in the southern Antarctic Peninsula and Ellsworth Land, Antarctica. We assess the regional variability in diatom composition and abundance at annual and sub-annual resolution across all four sites. These data corroborate the dominance of contemporary marine diatoms in Antarctic Peninsula ice cores, reveal that the timing and amount of diatoms deposited vary between low and high elevation sites and support existing evidence that marine diatoms have the potential to yield a novel wind paleoenvironmental proxy for ice cores in the southern Antarctic Peninsula and Ellsworth Land.

Regional validation of the use of diatoms in ice cores from the Antarctic Peninsula as a Southern Hemisphere Westerly Wind proxy

“…The relationship between diatom abundance and environmental parameters at the ice core drilling sites are weak and not statistically significant. Indicating that conditions at the ice core site are not drivers of the diatom temporal variability, in agreement with previous studies concluding that ice core diatom records are not dependent on annual snow accumulation or local wind conditions (Allen et al, 2020;Tetzner et al, 2021a). Spatial correlations of annual wind strength and the annual diatom abundance preserved in ice cores reveal regions of significant positive correlations (0.6≤R≤0.78, p<0.05) (Figure 3).…”

“…CC BY 4.0 License. indicated by the ecology of the dominant marine diatom taxa (Tetzner et al, 2021a). Furthermore, the neighbouring ice core sites of JUR and SKBL share similar regions of spatial correlation (0.67≤R≤0.78, p<0.05) (Figure 3).…”

“…The Sky-Blu ice core (SKBL, 21.8 m) from the vicinity of Sky-Blu Field Station, southern AP, and the Sherman Island ice core (SHIC, 21.3 m) from Eights Coast, were drilled using a Kovacs hand-auger during the austral summer 2019/2020. For JUR, SKBL and SHIC, an ice core chronology was established (Tetzner et al, 2021a) based on their hydrogen peroxide (H2O2) annual cycle that is assumed to peak during the austral summer solstice and to exhibit its minimum during the austral winter (Frey et al, 2006;Thomas et al, 2008). Ice core chronologies were corroborated using the annual cycle of the non-sea salt component of major ions, such as non-sea salt sulphate (nssSO4 2-) (Piel et al, 2006), that is assumed to peak between November and January in this region (Pasteris et al, 2014;Thoen et al, 2018).…”

“…Since diatom concentrations at SHIC peak during the austral summer (Tetzner et al, 2021a), spatial correlations for the SHIC diatom record were also calculated over 6-month period covering the austral spring & summer season (September-February).…”

“…Once in the atmosphere, they can be transported by winds over long distances (Gayley, 1989;McKay et al, 2008;Harper and McKay, 2010). Diatom records have been evaluated at multiple ice core sites in the AP and Ellsworth Land (EL) regions (Tetzner et al, 2021a) to reveal consistent spatial variations and increases in the diatom concentration during the past three decades. Despite the potential the diatom record has shown to reconstruct past wind strength, this proxy requires evaluation against more established ice core wind proxies.…”