On the way to Cape Town we continued with our regular underway measurements, only interrupted by two full stations with CTD and plankton nets on Monday (ca. 10°S) and Thursday (20°15’S). The last CTD on Thursday was celebrated and we were a bit sad that this was the last station.
As the students are now well-trained in the work on deck and data collection, a “surprise” CTD station was scheduled for Saturday, that was operated only by the students. This was a test how well they are now capable to run a sampling station by themselves. After the long weeks at sea, they passed the test with flying colours.
The weather was kind to us all the time although the southeasterly Trade Winds are increasing. At 21°S we experienced the unusual situation that the sun was directly overhead in the zenith and our shadows nearly disappeared. Every day the water and air temperatures are getting cooler as we are moving further south and reach the Benguela upwelling region.
Although our cruise track only touches the western edge of the Benguela current we found clear signals of the upwelling in our measurements and samples. The Continuous Plankton Recorder (CPR) showed patchy distribution of plankton that is caused by eddies and filaments of the upwelled water and is seen on the satellite images (Fig.1). On the last station we found surprising amounts of gelatinous organisms such as comb jelly fish and large Salps. Generally these last stations had more Diatoms, many different Dinoflagellates and Coccolithophorids. On this cruise the students developed a phytoplankton identification guide that will be very helpful for future investigations in this region (Fig. 2).
The students are now very busy with the analysis of the data. The combination of the different data sets more and more reveals the specific characteristics of the different oceanic regions that we have crossed. The puzzle is starting to make sense.
Now we are packing, and the sampling has ended. All are busy writing the reports. On Tuesday, 01 December 2015, in the morning we reach Cape Town after a successful and very good Polarstern cruise PS95.
With best wishes from all on board Polarstern,
Karin Lochte
