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The subarctic Pacific Ocean experiences strong climate-modulated seasonal, interannual to decadal variations in meteorological and physical oceanographic conditions, which can have a profound influence on biological processes and carbon cycling in the region. Inorganic nitrate, a major nutrient controlling phytoplankton growth, is key to understanding the export of organic matter out of the euphotic zone. Its supply to the region is driven largely by winter convective mixing. Using satellite data for a 5-year period beginning in 1997, we provide evidence of strong interannual variations in the supply of inorganic nitrate and new production in the subarctic Pacific in association with the El-Niño of 1997 and the transition to La-Niña conditions thereafter. These satellite based climatologies allowed us to view and describe large changes in nitrate distribution and new production along the entire breadth of the subarctic Pacific basin. In addition, our accessibility to a 25-year database of shipboard measurements focused primarily in the Oyashio waters, a region representative of the western subarctic Pacific, enabled us to demonstrate that El-Niño/La-Niña changes in this region differed from those observed in the eastern subarctic Pacific. Thus, in addition to the primary motive of verifying the changes that we observed in our satellite-derived maps, this exercise allowed us to obtain a clear picture of the mechanistic connections between the atmosphere and the oceans and the biological response to these changes. The results from this study make a compelling case that the primary driver for the observed interannual variations in biological production in the western subarctic Pacific is the strength of the wintertime monsoonal winds. This anomalous intensification of the southeastward wind stress appears to be particularly strong during El-Niño years when the Aleutian Low intensifies and moves southeastwards, causing disturbances in the pressure gradient between the Siberian high and the Aleutian Low. An abrupt shift in oceanographic conditions follows this change in pressure gradient, among them the most prominent being a reduction in sea surface temperature, a southward migration of the belt of zero wind-stress curl, and the anomalous southward penetration of the Oyashio Current. In tandem, these changes, contribute to an increase in nutrient inputs in winter and a southward displacement of the boundary of the subarctic gyre. The spring following an El-Niño event is characterized by reduced wind stress and a resulting increase in water column stability as well as the elevated solar radiation leads to blooms. Conversely, in the winter of 2000, the subarctic gyre experienced the weakest winds of all 5 years. These weak wind conditions were associated with increased wind speeds in spring of that year and the lowest annual rates of new production of all 5 years. [Copyright &y& Elsevier]

Variability of hydrographic conditions and primary and secondary productivity between cold and warm climatic regimes in the Bering Sea has been the subject of much study in recent years, while interannual variability within a single regime and across multiple trophic levels has been less well-documented. Measurements from an instrumented mooring on the southeastern shelf of the Bering Sea were analyzed for the spring-to-summer transitions within the cold regime years of 2009-2012 to investigate the interannual variability of hydrographic conditions, primary producer biomass, and acoustically-derived secondary producer and consumer abundance and community structure. Hydrographic conditions in 2012 were significantly different than in 2009, 2010, and 2011, driven largely by increased ice extent and thickness, later ice retreat, and earlier stratification of the water column. Primary producer biomass was more tightly coupled to hydrographic conditions in 2012 than in 2009 or 2011, and shallow and mid-column phytoplankton blooms tended to occur independent of one another. There was a high degree of variability in the relationships between different classes of secondary producers and hydrographic conditions, evidence of significant intra-consumer interactions, and trade-offs between different consumer size classes in each year. Phytoplankton blooms stimulated different populations of secondary producers in each year, and summer consumer populations appeared to determine dominant populations in the subsequent spring. Overall, primary producers and secondary producers were more tightly coupled to each other and to hydrographic conditions in the coldest year compared to the warmer years. The highly variable nature of the interactions between the atmospherically-driven hydrographic environment, primary and secondary producers, and within food webs underscores the need to revisit how climatic regimes within the Bering Sea are defined and predicted to function given changing climate scenarios.