21 July 2013
Thursday in bright sunshine, Tara scientists did the last long station of the Murmansk-Dudinka leg. All measuring instruments are now turned off, because Tara is entering the mouth of the Yenisei River. Lee Karp-Boss, chief scientist of the leg, reviews this month of adventure and sampling, now coming to an end for her and her team.
- Lee, how was the last long scientific station, and what were its characteristics?
The last long sampling station was relatively short, given the site’s shallow waters – only 36 meters. We were interested in sampling in this zone where the Kara Sea is under the influence of water masses from the Yenisei River. Salinity was very low, at level 12, while in the Barents Sea it was 34.8. We collected a lot of fish larvae in the nets. We also observed a high concentration of dissolved organic matter (commonly called CDOM – colored dissolved organic matter) which gave the water a dark green color. But this isn’t surprising in a coastal zone, since the CDOM usually comes from land.
- In general, what was the result of this leg?
From my perspective, this leg was very productive. Exceptional weather conditions facilitated our work, and we were able to accomplish all the planned stations. The experience of the crew – scientists as well as sailors – was a real plus for the smooth running of sampling stations. We did a total of 15 stations, including 5 long ones. Especially interesting is that we sampled in various environments, with different conditions. During these stations, we observed changes in the plankton community. For example, the size and quantities of phytoplankton were greater among the ice than in the ice-free Barents Sea. But this is only simple observation. Genetic and taxonomic studies will tell us if there was actually a great diversity. We also had the opportunity to work twice in the Gorge of Santa Anna, at different positions. Recorded data on physical properties of the water will allow researchers to continue their studies concerning the movement of currents, particularly interesting in this area. And let’s recall that by studying the movement of currents, we can better understand the impacts of climate change.
- Apart from the plankton samples sent to many laboratories, how will the data collected during the Tara Oceans Polar Circle expedition be used?
We have, among others, a partnership with NASA – the U.S. Agency for aeronautics and space, and also with ESA, the European Space Agency. At the end of the expedition, after checking our numbers, we will send these agencies physical data on the absorption and deflection of light in these waters, and biological data on the type of particles present in the area studied, and their concentration. This information will help readjust the algorithms that make a link between satellite maps showing ocean color, and chlorophyll concentration in the Arctic.
- What’s going to happen next?
I will leave the boat in Dudinka, and Pascal Hingamp will take over as chief scientist. During the second leg in Russia, the boat is supposed to return to an area that we have already studied – between Murmansk and Dudinka. The scientific advisory committee is considering the interest of sampling again in the same zone, a month later, to see the changes. In any case, after the Kara Sea, the team will be sampling in another environment, the Laptev Sea.
Interview by Anna Deniaud Garcia