How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Primary Production in the Bering Sea
Brown, Z.W., van Dijken, G.L. and Arrigo, K.R. 2011. A reassessment of primary production and environmental change in the Bering Sea. Journal of Geophysical Research 116: 10.1029/2010JC006766.

"Regarded as one of the world's most productive marine environments," in the words of the authors, "the Bering Sea is widely thought to be rapidly warming and losing sea ice," and they say that "such changes would be expected to have dramatic impacts on primary producers, with cascading effects on upper trophic levels, including this region's vast commercial fisheries resources," which support "nearly half of the U.S. fishery annual catch and prolific benthic biomass."

What was done
In light of the widespread assumption that the Bering Sea is "rapidly warming and losing sea ice," Brown et al. employed "satellite-derived sea ice concentration, sea surface temperature, and ocean color data as input to a primary productivity algorithm to take stock of environmental change and primary production in the Bering Sea" under such transitory conditions.

What was learned
"Rather than declining," as the three U.S. (Stanford University) researchers report, they found that mean annual sea ice extent in the Bering Sea "has exhibited no significant change over the satellite sea ice record (1979-2009)," because, as they discovered, significant warming during the satellite sea surface temperature record (1982-2009) "is mainly limited to the summer months." In addition, and despite certain hot spots of primary production and a strong pulse in the spring, they also determined that "the rate of annual area-normalized primary production in the Bering Sea (124 g C per m2 per year) is below the global mean (140 g C per m2 per year)." And as a result of "comparing warm, low-ice years (2001-2005) with cold, high-ice years (1998-2000 and 2006-2007)," they were driven to conclude that "Bering Sea primary productivity is likely to rise under conditions of future warming and sea ice loss." And that rise could be quite substantial, as they report that "basin-wide annual primary production ranged from 233 to 331 Tg C per year under the influence of highly variable sea ice and temperature conditions."

What it means
Noting that the results they obtained were brought about by "a complex suite of changes in sea ice cover, temperature, stratification, spring bloom timing, and species composition," Brown et al. say that these several factors "will determine the fate of future net primary production in the Bering Sea," while further noting that the changes they observed "are likely a prelude to a similar drama playing out over Arctic shelves." And in light of what they learned about basin-wide biological productivity in the Bering Sea, that pan-Arctic drama should have a happy ending.

Reviewed 26 October 2011