The expedition is now about to end and we are heading back to Punta Arenas, where everything started almost 2 months ago. So, what did we do and learn so far?
First of all, we learned that crossing the Drake Passage and then the frozen sea in the Antarctic region implies a constant and intensified attention during navigation, forcing us to frequently readjust the original sampling plan. Whereas one needs to take advantage of the occurrence of favorable “weather windows”, the latter are often too short and variable in terms of visibility, ice cover, wind conditions and wave direction. It is crucial to have a firm hold and a quite a lot of flexibility to embrace what we affectionately call "dynamic planning."
In terms of sampling, we have sampled 98 stations in the region surrounding the Northern Antarctic Peninsula, with focus on the Bransfield Strait, Gerlache Strait, Antarctic Channel, Weddell Sea and Bellingshausen Strait, over the past 6 weeks. Seawater was collected at 5 different depths along the marine photic zone (between 5m and 150m) for the analysis of phytoplankton pigments through HPLC (High Performance Liquid Chromatography, see Mendes et al., 2018) and for the identification and quantification of phytoplankton species by microscopy. At specific sites, we also collected water for the study of the coccolithophore communities, a more tropical/subtropical group that has been reported to be increasing towards higher latitudes, possibly linked to climate-driven ocean warming and expansion of the oligotrophic subtropical gyres (Polovina et al., 2008; Rivero-Calle et al., 2015).
Our next step, after analyzing these samples, is to compare our in-situ observations with spatiotemporal data collected in the Atlantic sector of the Southern Ocean and around the Antarctic Peninsula over the last 15 years, by the GOAL team. In addition to all this ecological information, we will also use satellite data for a greater spatiotemporal coverage and to complement our more "snapshot" in-situ perspective. Comparison between the two types of observations will also enable calibration and validation of satellite data, crucial for making these data more reliable.
Overall, the 37th OPERANTAR has been a long and rich expedition, resulting from the enthusiasm of all the participants and of the overall good meteorological conditions that prevailed during most of the time. We have very high expectations from this scientific collaboration, and we anticipate interesting and highly relevant discoveries in the context of the effects of climate change on marine productivity in general, and on coccolithophore communities in particular. This will allow us to expand our DUSTCO’s transatlantic assessment on the impact of atmospheric dust towards an environmentally broader perspective, to explore the influence of other sources in addition to African dust (e.g. Patagonia and Northern Argentina) influencing the Atlantic Ocean.
For now, though, it is time to begin preparing for the return to the non-austral world, crossing the emblematic Drake Passage to go back to the “real world” and to the “normal life” :-). We are most grateful to GOAL and PROANTAR for the opportunity to be part of this simply amazing Antarctic expedition!!! As we Portuguese and Brazilian people say: JÁ ESTAMOS COM SAUDADES :-)