Planktic foraminifera sampling for culturing experiments, Central Greenland Sea 75°N

Our first ARCLIM cruise and the start of our first culturing experiments.  

We embarked on Monday 28^th June 2021 in Tromsø and started sailing northwest towards the Fram Strait (77°N, 0°). The weather started cloudy and with 8-12 m/s winds, but quickly turned exciting as we existed the sheltered fjords. This day was spent setting up and securing our equipment and adjusting to sea-legs as winds increased to 27 m/s by the evening. Due to storms, we changed course to the west to avoid  the worst weather. Tuesday was a transit day with strong winds and heavy swell.  

Early morning Wednesday we had reached 75°N, 2°E, and were ready for sampling. The winds were between 16 and 21 m/s, so sampling had to be done on short notice over the course of the day when the winds were on lows and on the leeward side of the ship. We deployed the plankton net 10 times on this day to collect foraminifera for culturing experiments. We also deployed the CTD six times for water sampling and collecting water to filter for culturing water. The scientists on board spent the day picking foraminifera for culturing, filtering seawater and preparing water treatments (altering water chemistry) for the experiments. 

Thursday was a repeat of Wednesday in many ways, the weather still came with strong winds and heavy swell. We therefore relied on deploying equipment on the leeward side of the ship and deployments on short notice when the winds were lower than 20 m/s. The highly experienced crew and captain of the R/V Helmer Hanssen made the sampling efficient despite the challenging conditions.  

For the scientists on board, we all got quite used to performing our work-duties under heavy swell. Working with living foraminifera and water, this meant our samples kept moving under the microscope as we attempted to pick our specimens. In the water filtration and preparation areas, it meant precariously balancing jerricans while trying to keep our own balance as 4-6 m swell hit.

Thursday evening we started the return to Tromsø with one more station for plankton nets and CTD planned along the way. We reached the final station around lunch-time Friday and deployed the CTD and plankton several times. The weather was clearing up and by the time we continued sailing towards Tromsø and arrived in Tromsø around lunchtime Saturday it was pleasant and sunny.  

We collected more than 1000 Neogloboquadrina pachyderma (polar planktic foraminifera) for culturing experiments for geochemical proxy development (lead by Adele W.) and reproduction experiments (lead by Julie M.). We also filtered more than 300L of seawater oonboard to be used as culture water.  

We are immensely grateful to the crew and captain of the R/V Helmer Hanssen and IG cruise engineer Truls Holm for excellent scientific support, particularly given the challenging weather conditions, which allowed us to complete a very successful scientific cruise, obtaining more than we had dared to hope for. 

You can read the Cruise Report here.

Text by Adele Westgård.