Effects of the Pacific Antarctic Circumpolar Current on the extant coccolithophore Emiliania huxleyi

During the last decades, the Southern Ocean (SO) has been experiencing physical and chemical drastic changes which are affecting the distribution and composition of pelagic plankton communities. Coccolithophores (small-sized haptophyte algae) are the most prolific carbonate-producing phytoplankton group, playing a key role in biogeochemical cycles at high latitudes.

In this work we investigated the biogeographical distribution and calcification patterns of the ecologically dominant species Emiliania huxleyi across a latitudinal transect in the Pacific sector of the SO (from ~40°S to ~54°S). We aimed to assess the response of E. huxleyi to steep environmental gradients across the frontal system of the Antarctic Circumpolar Current.

The plankton samples were collected during International Ocean Discovery Program Expedition 383: Dynamics of Pacific Antarctic Circumpolar Current (DYNAPACC, May-July, 2019) onboard the R/V JOIDES Resolution (https://iodp.tamu.edu/scienceops/expeditions/dynamics_of_pacific_ACC.html). In situ environmental data (such as sea surface temperature, total alkalinity and pH) were measured at each sampling location.

The samples were prepared and analysed at the University of Portsmouth using a combination of electron backscatter diffraction (EBSD), Scanning Electron Microscope (SEM) and light microscopy techniques.