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After a week of sampling and spraying, thus ended not just our part of the work but the whole spring mesocosm campaign. With our supplies packed and ready to be shipped back to the US we said goodbye to everyone at GEOMAR and gave them gifts we had brought – hats and mugs from our department.

On April 2nd, our last full day in Kiel, Diksha and Vignesh headed over to the new GEOMAR building on the east shore of the fjord to finish processing some samples that will be analyzed at a German facility. Meanwhile I went back to the old building to arrange shipments and got to see the GEOMAR team dismantling the mesocosm setup!

RS ALKOR, one of GEOMAR’s research vessels, arrived to help with this process.

After detaching the sediment traps from the bottoms of the bags, a couple guys got in the water and detached the mesocosm frames from the pier – in the above photo, a few mesocosms have already been removed.

Next, Levka and Jan tied them to a small motorboat to bring them to ALKOR in pairs (see next photo).

Finally, they were craned onto ALKOR and scientists onboard cut the used mesocosm bags off of the metal frames (don’t worry, all the growth you can see in this photo is on the outside of the bags).

With the mesocosms dismantled and everything squared away in lab, the three of us parted ways temporarily before reconvening back in Hanover.

Time to discuss sampling!

Each day at the mesocosms started at 7 am when Jana, one of the Riebesell group technicians, would collect the sediment trap samples. Thankfully she did not need our help, so our days started closer to 8 when we would arrive and take water samples from our three mesocosms. Shown below is one of the sampling tubes in use.

You can see the one of the red valves on the black part of the tube near the end Diksha is sampling from – there is a matching valve on the opposite end of the tube, and both are attached to each other by a piece of line. To sample a mesocosm the tube is dipped into the water, held by the “sampling” end with both valves open. The user can close the red valve on the sampling end, which should be near the surface of the water, and can then pull on the line to close the second valve at the bottom of the tube. It is then carefully pulled out and samples can be directly taken from the small piece of tubing at Diksha’s end in the photo here. In this particular instance she is taking a sample for Dr. Kai Schulz, who measured parameters such as pH and total alkalinity.

After our water was collected we brought it inside to aliquot and process the samples. Andrea (another Riebesell group technician who provided invaluable support during our trip), Jana, and Kai helped with many of our parameters such as inorganic nutrient analyses and provided CTD data (salinity, temperature, etc). For other parameters, such as chlorophyll, we did as much prep as we could and them froze the samples so they could be shipped back and analyzed in our facilities at Dartmouth.

Before we sprayed any clay, we also took 30 L of control seawater so that we could bring the water back here for another microcosm experiment. Below is Dr. D Sharma with her plankton babies resting comfortably in the outdoor incubator.