Ice retreat in the eastern Antarctic Peninsula region: the application of diatoms for understanding climate change

Abstract

Abstract Climate-driven retreat of ice shelves on the eastern side of the Antarctic Peninsula has opened up new coastal marine environments, enabling the development of primary productivity. Diatom assemblages in surface sediment samples from the eastern side of the Antarctic Peninsula were analyzed to investigate the use of diatoms as paleoenvironmental indicators of changes in glacial and sea ice extent. Here we present surface sediment diatom assemblage data from samples taken on 5 cruises between 2000-2012 from the northeastern-most tip of the Antarctic Peninsula, Prince Gustav Channel, Larsen A and Larsen B embayments, and a single sample from just east of Larsen C Ice Shelf. Absolute diatom abundance increases to the northeast reflecting greater contribution of diatom valves originating from surface waters that are ice free for a longer period of time. This trend is mirrored by the relative abundance of Chaetoceros subg. Hyalochaete, a spring bloom indicator group. The genus Fragilariopsis is dominated by sea ice-associated species, including Fragilariopsis curta, Fragilariopsis cylindrus, Fragilariopsis obliquecostata, Fragilariopsis sublinearis and Fragilariopsis vanheurckii. Fragilariopsis spp. relative abundance varies inversely with Chaetoceros subg. Hyalochaete. Distributions of Thalassiosira antarctica T1 and Thalassiosira antarctica T2, interpreted as a cooler and warmer forms, respectively, while generally inverse to one another with the T. antarctica T2 more common to the northeast, are not straightforward, with a pocket of high relative abundance in Larsen B embayment. These diatom data and their comparison to modern oceanography of the eastern Antarctic Peninsula provide a basis for further paleoceanographic work in the region.