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Despite being located at higher latitudes with seasonal ice-cover, the Bering shelves and slope are still one of the most productive regions of the world. Existing reports regarding marine production of the Bering Sea are mainly confined to its high water column production and high biomass of macrobenthos. Compared with biomass, secondary production estimates are more functionally based and have assumed a fundamental role in the quantification of ecosystem dynamics. Based on Brey's empirical model (in: Brey, Population dynamics in benthic invertebrates. A virtual handbook, Alfred Wegener Institute for Polar and Marine Research, Germany, 2001), macrobenthic production across the majority of the Bering Sea was quantified during the 4th, 5th and 6th Chinese Arctic Scientific Expeditions. Mean total production (TP) and community P/B for the entire survey area were 220.6 ± 341.5 kJ m−2 year−1 and 0.4 ± 0.2 year−1, n = 46, respectively. Higher TP occurred in the shallower shelves and slope with values exceeding 131.0 kJ m−2 year−1, whereas lower TP occurred in the deep basin with values of 1.0 kJ m−2 year−1. Comprehensive analysis revealed that the sediment, water flow, temperature and depth were the major factors affecting the macrobenthic production. Owing to the relatively high biological production in the upper water column and the tight pelagic-benthic coupling, higher production occurred in the shallow shelves and slope, particularly in the northern Bering Sea. In contrast, the high-nutrient, low-chlorophyll characteristic and deficient particulate organic carbon input led to low production in the deep basin. Similar to the conditions in the Arctic and Antarctic, the energy conversion rate of macrozoobenthos was relatively low for the Bering Sea. [ABSTRACT FROM AUTHOR]

For the first time, the reconstruction of variations in the duration over several hundred years was conducted on the basis of models developed by comparing hydrometeorological observations and detailed scanning of the chemical composition of bottom sediments accumulated during the corresponding period. The gauge models for the reconstruction of air temperature and ice cover of the water area for three sites in the northern part of the Chukchi Sea have been developed. During the reconstruction, an insignificant increase in the duration of the ice-free period during the Little Ice Age was established, which does not coincide with the changes in the temperature regime that took place. It is concluded that the dynamics of the inflow of warm Pacific waters through the Bering Strait had the predominant influence on the ice regime of the Chukchi Sea. [ABSTRACT FROM AUTHOR]