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Responses of Barents Sea Productivity to Recent Climate Change
Dalpadado, P., Arrigo, K.R., Hjollo, S.S., Rey, F., Ingvaldsen, R.B., Sperfeld, E., van Dijken, G.L., Stige, L.C., Olsen, A. and Ottersen, G. 2014. Productivity in the Barents Sea - Response to recent climate variability. PLOS ONE 9: e95273.

The Barents Sea is an open sub-Arctic shelf ecosystem situated north of Norway and northwest of Russia that covers an area of 1.6 million km2. It supports some of the world's largest stocks of cod, capelin and haddock; and it is the chief nursery for the large stock of spring-spawning Norwegian herring. In addition, it is home to one of the largest concentrations of seabirds in the world and a diverse assemblage of marine mammals, all of which are ultimately sustained by a rich and diverse community of plankton.

What was done
In the words of Dalpadado et al., "the temporal and spatial dynamics of primary and secondary biomass/production in the Barents Sea since the late 1990s were examined using remote sensing data, observations and a coupled physical-biological model," while "field observations of mesozooplankton biomass, and chlorophyll a data from transects (different seasons) and large-scale surveys (autumn) were used for validation of the remote sensing products and modeling results."

What was learned
In the area of climate, the ten researchers report that since the early 1970s there has been a long-term temperature increase in the Barents Sea's southern region of almost 1.5°C, citing the studies of Ingvaldsen et al. (2003) and Johannesen et al. (2012); and they say there has consequently been a "drastic sea ice decrease, increased open water area and prolonged duration of the open water season," such that "there has been an increase in NPP [net primary production] during the recent warming," citing Drinkwater (2011) and adding that their own analysis of "the NPP time series based on satellite-derived data similarly indicates that NPP in the Barents Sea ecosystem has increased moderately over the years (1998-2011), likely influencing the production at higher trophic levels." And they say that "positive significant associations between NPP and fish biomass in this region is also indicative of bottom-up forcing on higher trophic levels."

What it means
In light of these several findings, Dalpadado et al. conclude that the "high pelagic fish biomass and good feeding conditions currently observed in the Barents Sea ecosystem (Dalpadado et al., 2012; ICES, 2012), and also observed in this study is likely a positive response to changes in climate," which in this case was a modest warming of the sea.

Dalpadado, P., Ingvaldsen, R.B., Stige, L.C., Bogstad, B., Knutsen, T., Ottersen, G. and Ellertsen, B. 2012. Climate effects of Barents Sea ecosystem dynamics. ICES Journal of Marine Science 69: 1303-1316.

Drinkwater, K.F. 2011. The influence of climate variability and change on the ecosystems of the Barents Sea and adjacent waters: Review and synthesis of recent studies from the NESSAS Project. Progress in Oceanography 90: 47-61.

ICES. 2012. Report of the working group on widely distributed stocks (WGWIDE), Lowestoft, United Kingdom, 21-27 August 2012. ICES CM 2012/ACOM: 15, 931 p.

Ingvaldsen, R., Loeng, H., Ottersen, G. and Adlandsvik, B. 2003. Climate variability in the Barents Sea during the 20th century with a focus on the 1990s. ICES Marine Science Symposium 219: 160-168.

Johannesen, E., Ingvaldsen, R., Bogstad, B., Dalpadado, P., Eriksen, E., Gjosaeter, H., Knutsen, T., Skern-Mauritzen, M. and Stiansen, J.E. 2012. Changes in the Barents Sea ecosystem state, 1970-2009: climate fluctuations, human impact, and trophic interactions. ICES Journal of Marine Science 69: 880-889.

Reviewed 13 August 2014