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The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100–1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate) were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will increase the frequency and scale of toxic blooms and the toxin contamination of plankton feeders. This poses serious threats to humans and the marine ecosystem. [ABSTRACT FROM AUTHOR]

Crustacean decapods are key components that structure the benthic ecosystems in the Subarctic/Arctic regions and support one of the largest fishery industries, but their larval dynamics are largely unknown. To investigate variability in decapod larvae community in this region, we analysed plankton samples collected during the summers of 2007 and 2008 along the southeastern Bering and Chukchi Seas. Distribution of adult population was studied using bottom trawling during 2008 cruise. Larvae of Pagurus spp., Hyas spp., and the commercially important Chionoecetes bairdi and Chionoecetes opilio were the most abundant species. The distribution of benthic adults linked to those of planktonic larvae and may favour recruitment near suitable habitats and the maintenance of the populations. Earlier larval stages of C. bairdi, C. opilio, and Hyas spp. were more abundant in 2008 than in 2007. The body size of C. opilio showed a significant latitudinal pattern, in which larger sizes occurred at higher latitudes in association with distinct temperature and food conditions. We argue that annual changes in abundance and developmental stage structure of planktonic larvae seemed to be related to the 1 month delay in the sampling period and are not determined by the contrasting environmental conditions observed in both years. [ABSTRACT FROM AUTHOR]

From July to August 2007 and June to July 2008, the horizontal/geographical changes in the zooplankton community in the Bering and Chukchi Seas were studied. The geographical patterns, which were common for these two years, were observed for salinity, chlorophyll a (Chl. a ), zooplankton chaetognaths, hydrozoans and the whole zooplankton community. Among them, the patterns of salinity and Chl. a were related with the horizontal distribution of the water masses. The distributions of the two carnivorous taxa were correlated with their prey (copepods or barnacle larvae). The analysis of the structural equation model (SEM) revealed that the horizontal distribution of the zooplankton abundance and biomass were governed by the different taxa. Thus, the zooplankton abundance was governed by the numerically dominant but smaller-bodied taxa, such as the barnacle larvae and copepod Pseudocalanus spp., while the zooplankton biomass was determined by the large-bodied copepods, such as Calanus glacialis / marshallae and Eucalanus bungii . [ABSTRACT FROM AUTHOR]

Hirawake, T., Shinmyo, K., Fujiwara, A., and Saitoh, S. 2012. Satellite remote sensing of primary productivity in the Bering and Chukchi Seas using an absorption-based approach. – ICES Journal of Marine Science, 69: .Ocean colour remote sensing has been utilized for studying primary productivity in the Arctic Ocean. However, phytoplankton chlorophyll a (Chl a) is not predicted accurately because of the interference of coloured dissolved organic matter (CDOM) and non-algal particles (NAP). To enhance the estimation accuracy, a phytoplankton absorption-based primary productivity model (ABPM) was applied to the Bering and Chukchi Seas. The phytoplankton absorption coefficient was determined correctly from sea surface remote sensing reflectance (Rrs) and reduced the effect of CDOM and NAP in primary productivity (PPeu) estimates. PPeu retrieved from in situ Rrs using the ABPM satisfied a factor of 2 of measured values. PPeu estimated from the Moderate Resolution Imaging Spectroradiometer Rrs data were within the range of historical values. These estimated PPeu values were less than half of those of the model based on Chl a, and the difference between the two models reflected the influence of CDOM and NAP absorptions. Interannual variation in August and September over the period 2002–2010 showed an increase in primary productivity. The increase in 2007 was especially large, by a factor of 1.51–2.71, compared with 2006. The significant temporal increase in productivity detected here differs from earlier studies that detected little, if any, change in the region. [ABSTRACT FROM PUBLISHER]