Fate of the Arctic spring bloom

Disko Bay in West Greenland has been the site of Arctic research since 1906. Since 1992, the seasonal plankton community structure, succession and production at a 300 m deep station off Qeqertarsuaq have been investigated.

Disko Bay is a very productive area and is very important for commercial and recreational fishing and hunting. The bay is located at the outlet of Jakobshavn isbræ, the most productive glacier in the northern hemisphere. After breaking up, the icebergs emerge into the bay proper and initially travel north with ocean currents before turning south and running into the Atlantic Ocean.

Glacier ice production and sea ice from Disko Bay substantially influence the initiation of the productive cycle of the plankton community. The Arctic spring phytoplankton bloom is the key event in high latitude marine ecosystems, contribution with the major part of the annual primary production and responsible for fuelling the high secondary production. It is triggered by the sea ice break-up combined with a warming and freshening of the surface layer stratifying the water column.

The bloom is characterised by a short and pronounced growth peak of diatoms that depletes the surface layer of nitrate and subsequent sediments. Sedimentation of phytoplankton from the euphotic zone is the principal mechanism in transport of organic material to benthic communities. The transport occurs directly as intact cells or indirectly as faecal pellets from pelagic grazers, aggregates and amorphous detritus. During its transit to the sea bed, the organic material is modified by the pelagic heterotrophs in a way that influences its quantity and quality as a carbon source for the benthic community.

No advanced courses have previously been hosted in the Arctic to investigate and describe the processes associated with the spring bloom. During this course, all major processes will be quantified by different groups of students so the joint effort of all student groups will give an opportunity to demonstrate quantify the diverse routes of organic matter related to the termination of the spring bloom and the transition phase to a more regenerated stratified summer situation. By bringing Nordic and international guest scientists together the students will get a hands-on experience of Arctic biological oceanography.

Facts about the project
Project leader

Torkel Gissel Nielsen, Technical University of Denmark (DTU), Denmark