Variations of primary production rates in the Bering Strait and Chukchi Sea.

Abstract

The nutrient and productivity processes are not well known in the regional sense for the northern Bering and Chukchi Seas since very few cruises have been able to adequately sample across the political boundaries, although these regions are the only conduit of water masses and organic matter between the North Pacific and Arctic Oceans. The quantity of nutrients and organic matter flowing through these major regions and subsequently into the Arctic Ocean must be determined to understand the effects of ongoing climate changes on the Arctic marine ecosystem. Based on in situ measurements for chlorophyll-a and primary production in 2003-2004, the seasonal and annual variations of primary production in the regions were examined from the satellite ocean color images (MODIS) during recent years from 2002 to 2006. Generally, phytoplankton in Bering Strait and Chukchi Sea start to grow after retreats of seasonal pack ice in May and their growth slow down in September. The western parts of the strait and central Chukchi Sea show very high phytoplankton biomass because of the Anadyr Current effects. In addition, the seasonal and annual variations of chlorophyll-a concentration and primary production rate were generally higher in the western side than in the eastern side of the Bering Strait region. The production rates in the central Chukchi Sea as a "hot spot" also was rather variable in different seasons based on the average production from 2002 to 2006. The range of the estimated production rates in the hot spot was from 1.3 to 4.4 g C m-2 d-1 with an average of 2.6 g C m-2 d-1.