Climate change and the control of energy flow in the southeastern Bering Sea

Abstract

We examine how coupling between physical and biological processes influences the production and transfer of energy to upper trophic-level species in the southeastern Bering Sea. We review time series that illustrate changes in the marine climate of the southeastern Bering Sea since the mid-1970s, particularly variability in the persistence of sea ice and the timing of its retreat. Time series (1995 -2001) from a biophysical mooring in the middle domain of the southeastern shelf support the hypothesis that retreat of the winter sea ice before mid-March (or the failure of ice to be advected into a region) results in an open water bloom in May or June in relatively warm water (Ն3°C). Conversely, when ice retreat is delayed until mid-March or later, an ice-associated bloom occurs in cold (Յ0°C) water in early spring. These variations are important because the growth and production of zooplankton and the growth and survival of larval and juvenile fish are sensitive to water temperature. The Oscillating Control Hypothesis (OCH) recently proposed by Hunt et al. (2002), predicts that control of the abundance of forage fish, and in the case of walleye pollock (Theragra chalcogramma), recruitment of large piscivorous fish, will switch from bottom-up limitation in extended periods with late ice retreat to top-down in warmer periods when ice retreat occurs before mid-March. In support of this hypothesis, we review recent data from the southeastern Bering Sea that show 2-to 13-fold changes in copepod abundance with changes in spring water temperatures of 3 to 5°C. We also provide indirect evidence that the abundance of adult pollock on the eastern Bering Sea shelf negatively affects the abundance forage fishes (including juvenile pollock) available to top predators. Although there is evidence that pollock year-class strength is positively related to temperature, we lack the time series of pollock populations in extended periods (8 -10 years) of cold-water blooms necessary to test the OCH. 

Environmental change in the eastern tropical Pacific Ocean: review of ENSO and decadal variability

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Summer Season Water Temperature Modeling under the Climate Change: Case Study for Fourchue River, Quebec, Canada

“…These studies can be divided into several topics: freshwater [18,20,21], saltwater [22][23][24], river [20,25,26], lake [27,28], ocean [29,30], global scale [21], etc. Furthermore, recent studies also have discussed water temperature change and its effect due to climate change on the aquatic environment such as ecosystem productivity [31,32] and biodiversity [24,33,34].…”

Sea Ice Response to Atmospheric and Oceanic Forcing in the Bering Sea

“…Significant changes in the Bering ecosystem have been measured in recent decades. Observations indicate that large-scale ecological ''regime shifts'' occurred in the Bering Sea during 1976-77, 1988-89, and 1998, affecting the mix and abundance of suites of coexisting species from primary producers to apex predators (e.g., Stockwell et al 2001;Benson and Trites 2002;Hunt et al 2002;Hunt and Stabeno 2002). A major ecosystem shift has also been observed in the northern Bering Sea (Grebmeier et al 2006).…”