Arctic Ocean Primary Production in the Next Decades: What are the Projections?

The basic ecological knowledge at the Arctic Ocean is insufficient to evaluate projections of arctic change with reasonable precision. In the European sector of the Arctic, three basic gross primary production (GPP) domains can be distinguished: (i) extensive and dominated by Atlantic Water, (ii) the stretched out strata of the seasonal ice zone and (iii) the compact perennial ice zone (>100, between 100 and 30 and < 30 g C m-2 y-1). Interannual coefficient of variation for primary production in domain (i) was <0.1, and increased northwards towards >0.6 in the north western– and northeasternmost fringe of the seasonal ice zone (SIZ). The primary production in the northern sector of the European Arctic Corridor region prior to 2007 was characterized by limited interannual variability, on average 75.2 g &plusmn 10% and 24.0 &plusmn 16% g C m-2 y-1 for the EAC region at 74–80 and >80&degN, respectively. The principal primary production anomalies are found early in the productive season and sections of the SIZ, in general regions of low GPP. There was no significant trend of increasing GPP in the 1994–2007 time interval. This is in contrast to the Canadian basin of the Arctic Ocean where reduced ice cover has resulted in significant increases in GPP. While climate change projections point at an average increase in GPP from about 10 to >30 g C m-2 y-1, the outcome with regard to the C flux is complex because increases in temperature and less ice result in also in strongly increased respiration, a strengthening of the microbial food web and dominance of smaller plankton species and a decrease of food availability for higher trophic levels. In concert this will result in a reversion of the C flux from today's uptake from the atmosphere to tomorrows release. When today's SIZ becomes thinner and retreats from the shelf towards the Arctic Ocean's interior, little of our current ecological knowledge can be applied because basically unknown processes.