22 June
Conclusion at the end of the Greenland Expedition: We have conducted much more experiments and measurements that expected

By Torkel Gissel Nielsen, cruise leader

After three weeks of around the clock research we have now taken the last samples in the inner most melt water influenced part of the Godthåbsfjord and are now steaming back to Nuuk.

 

The sampling at the station closet to the glacier was hindered slightly by the small ice bergs which prevented the use of the large towed nets. However, we managed to collect some important and unique samples of the nutrients, bacteria and microplankton. The rest of the sampling was then carried out in a lager ice free area a few kilometers from the ice.

 

 

Dana at the inner most station in Godthåbsfjord. Photo Colin Stedmon.

 
A characteristic feature of the inner most parts of the Godthåbsfjord is the melt water with clay and silt which gives the surface water a milky colour.

 

The plankton composition in this milky cold water in the inner part of the fjord is very different from what we have been working with at other locations in the fjord system. The particles in the water reduce the light available for the phytoplankton growth and accelerates the sedimentation of organic matter.

 

 

The research group on the sun deck. In the background is the glacier Narssae Sermia. The light color of the water is caused by silt and clay transported to the fjord by the melt water. Photo Rune Gaardboe Frederiksen.

 

The pycnocline: thin but productive

The pycnocline, the interface between the brackish surface layer and the more salty bottom water, is the site of enhanced biological activity.

 

This layer is often very thin and poorly sampled with conventional sampling equipment. To remedy this we have developed a sampler composed of a series of large syringes mounted on a frame so water samples can be taken at many depths across the pycnocline. Before filling the syringes we must ensure that the sampler is placed in the ideal position in the water column.

 

Using this sampler we have the opportunity to describe the thin high productive layers in the pycnocline. Sampling with the equipment generates several weeks of work in front of the microscope.  

 

   

Photo: To collect the thin layers of plankton in the pycnocline we use a 3 m high resolution water sampler, which can take samples instantaneously at many depths. Photo: Enric Saiz.

Graphic: The depth distribution of salinity (blue), temperature (red) and phytoplankton (green) in the upper 100 m of the water column at the entrance to the Kapsigdlidt fjord June 17. The largest concentration of phytoplankton is located in the transition zone between the brackish surface water and the colder and more saline bottom water (the pycnocline).  

 

Three weeks undisturbed research time

The cruise has gone much better than expected. Due to the calm seas at Fyllas bank and the exceptional constructive cooperation with Danas Captain and crew we have been able to conduct much more experiments and measurements that expected.

 

In addition there has been constructive collaborations between the different research groups on board. Everyone has worked hard, helping and inspiring each other, so that we have not only completed our plan work but also generated new ideas and plans for future work and collaboration within the framework of the Greenland Climate Research Centre.

 

The collected material and data will now be distributed between the different research groups and will be analyzed. The first presentation of the preliminary results will take place during the annual meeting of the Greenland Climate Research Centre November 2010 (further information see www.natur.gl).

 

Over the coming years the results from this unique cruise will be analyzed, described and published in international journals. The knowledge gained will help us understand the Godthåbsfjord ecosystem and the complex interactions between climate and the marine food web.

 

On the way to the innermost sampling station in Godthåbsfjorden. Photo Torkel Gissel Nielsen.   

 

Back to the real world

On the way back to Nuuk we are facing large logistical challenges with packing and securing the equipment and last but not least the precious samples, so they arrive safely to Denmark after a potentially rough cruise over the North Atlantic.

 

Though the cruise has been very succesfull the scientists and the crew are looking forward to coming back to the "real world". After working around the clock and being cut off from daily norms such as internet and telephone coverage, one looses track of time and days merge into one. This is actually a real privilege, as one can concentrate 100% on research. The only indication of which day of the week it is on Sunday and Wednesday where bacon is served for breakfast.

 

Now we are all looking forward to returning to our families and friends, and hopefully a nice warm summer.

 

Midsummer party in Nuuk

The end of the cruise will be celebrated in Nuuk, where we all are invited to a midsummer party with our colleges from the Greenlandic Institute of Natural Resources.

 

We will disembark Dana early in the morning on the 24th June, where there will be a change of crew. Dana departs to Denmark on the same day with a class of oceanography students ready for an adventure across the Atlantic back to Denmark.

 

Torkel Gissel Nielsen has headed the Greenland Expedition BOFYGO which is one of the most comprehensive surveys on the marine pelagic ecosystem in Greelandic waters. Torkel is a professor in environmental plankton ecology at DTU Aqua. The last 20 years he has been investigation the structure and function of pelagic ecosystems from the arctic to tropical ecosystems. Photo Mette Dalgaard Agersted.      Read cruise reports from 6 June to 13 June   Read cruise reports from 14 June to 21 June