Using biomarkers, a multidisciplinary team of scientists managed to collect paleoceanographic data from the Bransfield Strait, one of the Antarctic areas that is most affected by climate change.
In recent years and in an accelerated manner, the Western Antarctic Peninsula has suffered various variations in its temperature. According to the Intergovernmental Panel on Climate Change (IPCC), the Southern Ocean has largely absorbed the atmospheric heat generated by anthropogenic activity, the analysis of this phenomenon and how it is affecting the biodiversity present in the place is essential.
To know the impact of environmental variables in the Southern Ocean, a multidisciplinary team of researchers carried out a long history of paleoceanographic information in the Bransfield Strait, located between the Antarctic Peninsula and the South Shetland Islands.
After collecting sediment cores on board of the German ship Polastern, Chilean and German scientists carried out a reconstruction of the area by analyzing biomarkers, microorganisms such as diatoms and TEX86 (lipids from bacteria such as archaea,) as well as dating to determine an old model.
“Transfer equations were made from the abundance data of certain groups of diatoms, which helped to estimate paleotemperatures and ice cover,” said Dr. Lorena Rebolledo, researcher at the Center for Dynamic Research of Marine Ecosystems of High Latitude (IDEAL) of the Austral University of Chile (UACh) and co-author of the study.
The investigation accounted for the differences in controls of geographic variability. The sediment cores closest to the Antarctic Peninsula were influenced by the water masses of the Wedell Sea (colder,) while those on the south side were affected by the waters of the Bellinghausen Sea (warmer) and marine intrusions from the Antarctic Circumpolar Current (ACC.)
The importance of the study also lies in the presence and variability of marine ice in the area. “This element is very important for organisms such as krill, which feed on diatoms that attach to marine ice. In periods with a larger ice cover, there is greater recruitment of krill and a greater biomass of organisms that consume this species, such as whales and penguins, versus other years with less marine ice cover, which results in lower primary productivity,” stated Dr. Rebolledo, who is also a researcher at the Chilean Antarctic Institute (INACh).
In turn, the study concluded that changes in the marine ice layer are not only related to the entry of warm water and the increase in temperature on the sea surface, but also to other environmental variables such as the South Annular Mode (or SAM,) and the El Niño phenomenon.
The investigation, in which researchers from the Alfred Wegner Institute, University of Bremen (Germany), Pontificia Universidad Católica del Norte, Centro COPAS Sur-Austral of the University of Concepción (UdeC) and the Scripps Center of the United States participated, was published in the scientific journal Climate of the Past.