Anthropometric variation among Bering Sea natives

Recent research indicates that anthropometrics can be used to study microevolutionary forces acting on humans. We examine the use of morphological traits in reconstructing the population history of Aleuts and Eskimos of the Bering Sea. From 1979 to 1981, W. S. Laughlin measured a sample of St. Lawrence Island Eskimos and Pribilof Island Aleuts. These samples included adult participants from St. George and St. Paul in the Pribilof Islands and from Gambell and Savoonga on St. Lawrence Island. The Relethford-Blangero method was used to examine the phylogenetic relationship between Aleuts and Eskimos. Anthropometric measurements for Native North Americans (measured by Boas and a team of trained anthropometrists in 1890-1904) and Native Mesoamericans (compiled from the literature for 1898-1952) were used for comparison. A principal components analysis of means for measurements and a neighbor-joining tree were constructed using Euclidean distances. All these tests revealed the same strong relationship among the focus populations. The R matrix from the Relethford-Blangero method clusters Aleuts and Eskimos separately and accounts for 97.3% of the variation in the data. Phenotypic variation within the population is minimal and therefore minimum F(ST) values are low. Genetic distances were compared to a Euclidean distance matrix of anthropometric measurements using a Mantel test and gave a high but not significant correlation. Our results provide evidence of a close phylogenetic relationship between Aleut and Eskimo populations in the Bering Sea. However, it is apparent that history has affected the relationship among the populations. Despite previous findings of higher European admixture in Gambell (based on blood group markers) than in Savoonga, Savoonga has greater within-group variation in anthropometric measurements. Anthropometrics reveal a close relationship between Gambell and St. Paul as a result of European admixture. The St. George population was the most divergent of the populations, indicating that it diverged from the Eskimos and St. Paul because of the compounding effects of genetic drift and limited European gene flow. These findings are in agreement with previous anthropometric and genetic studies of the Aleut and Eskimo populations and support the utility of anthropometrics in inferring population history and structure.     

Pelagic Food Chain of the Bering Sea

Journal of Ichthyology - The order of magnitude of biomass and production at various trophic levels in the epipelagic community has been calculated, and the main pathways for the transformation of...     

Subtropical migrants in the southwestern part of the Bering Sea

From 2003 to 2008, arrivals (including mass) of sea bream Brama japonica, saury Cololabis saira, and spiny dogfish Squalus acanthias, as well as some cases of catches of Japanese anchovy Engraulis japonicus, and Todarodes pacificus, and Onychoteuthis borealijaponica squids were recorded in Pacific waters of Kamchatka in the southwestern sector of the Bering Sea. The penetration of these species far to the north is related to feeding migrations as well as to the passive transfer of water by currents. Migrations of subtropical species to Pacific waters of Kamchatka and the southern part of the Bering Sea depend on thermal conditions and circulation of currents in each particular year and are determined, first of all, by the intensity of the Western Subarctic gyre, although in some years, the migration flow of B. japonica and C. saira from the northeastern part of the Pacific Ocean increases.     

Environmental Predictors of Ice Seal Presence in the Bering Sea

Ice seals overwintering in the Bering Sea are challenged with foraging, finding mates, and maintaining breathing holes in a dark and ice covered environment. Due to the difficulty of studying these species in their natural environment, very little is known about how the seals navigate under ice. Here we identify specific environmental parameters, including components of the ambient background sound, that are predictive of ice seal presence in the Bering Sea. Multi-year mooring deployments provided synoptic time series of acoustic and oceanographic parameters from which environmental parameters predictive of species presence were identified through a series of mixed models. Ice cover and 10 kHz sound level were significant predictors of seal presence, with 40 kHz sound and prey presence (combined with ice cover) as potential predictors as well. Ice seal presence showed a strong positive correlation with ice cover and a negative association with 10 kHz environmental sound. On average, there was a 20–30 dB difference between sound levels during solid ice conditions compared to open water or melting conditions, providing a salient acoustic gradient between open water and solid ice conditions by which ice seals could orient. By constantly assessing the acoustic environment associated with the seasonal ice movement in the Bering Sea, it is possible that ice seals could utilize aspects of the soundscape to gauge their safe distance to open water or the ice edge by orienting in the direction of higher sound levels indicative of open water, especially in the frequency range above 1 kHz. In rapidly changing Arctic and sub-Arctic environments, the seasonal ice conditions and soundscapes are likely to change which may impact the ability of animals using ice presence and cues to successfully function during the winter breeding season.     

Feeding ecology of dominant groundfish in the northern Bering Sea

We investigated current diets of the six most abundant benthic fish in the northern Bering Sea. Our objective was to explore feeding strategies and potential competition with other top predators as ecosystem changes occur in the northern Bering Sea ecosystem. Our approach used stomach content data collected from field sampling during spring 2006 and 2007. Calanoid copepods and ampeliscid amphipods were important prey of Arctic cod (Boreogadus saida) but in different proportions depending upon fish size, feeding location, and local environmental conditions. Snailfish (Liparidae) occupied a broad niche and fed on a variety of benthic amphipods. Arctic alligatorfish (Ulcina olrikii) and Arctic staghorn sculpin (Gymnocanthus tricuspis) consumed ampeliscid amphipods predominantly. Shorthorn sculpin (Myoxocephalus scorpius) had a less-diverse diet, with snow crab (Chionoecetes opilio) most important by weight. Finally, all Bering flounder (Hippoglossoides robustus) sampled had empty stomachs. Our results indicate that ampeliscid amphipods, which have high biomass in the central region of the northern Bering Sea, are the most important prey for the dominant groundfish in the Chirikov Basin. Generally, all dominant benthic fish in the northern Bering Sea had narrow feeding niches, except snailfish. High diet overlap was found among many of the fish species, including Arctic cod and snailfish, snailfish and Arctic alligatorfish, and Arctic alligatorfish and Arctic staghorn sculpin. These findings are consistent with a relatively short food chain for benthic fish that are for the most part specialized feeders with narrow preferences for food and may be affected by changes in benthic prey distributions.     

Phylogenetic diversity of sediment bacteria in the northern Bering Sea

The bacterial diversity in sediments from the northern Bering Sea was investigated by culture-independent approaches. Community fingerprint analysis by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) revealed that sediment at two deep stations (DBSE and DBS1, >400 m in depth) harbored a bacterial community distinct from the sediments collected at shallow stations (<150 m in depth) on the continental shelf. Three 16S rRNA gene clone libraries for sediments collected from shallow to deep water stations (NEC5, DBSE and DBS1, respectively) were established. Sediment collected at the deepest station DBS1 showed the highest diversity index value. Sequences fell into 19 major lineages of the domain Bacteria: Alpha-, Beta-, Gamma-, Delta- and Epsilonproteobacteria, Bacteroidetes, Acidobacteria, Actinobacteria, Firmicutes, Planctomycetes, Nitrospirae, Verrucomicrobia, Chloroflexi, Chlorobi, Spirochaetes, Cyanobacteria (or chloroplasts), and candidate divisions OP8, TM6, and WS3. A small fraction of retrieved sequences (1.8%) did not fall into any taxonomic division. Deltaproteobacteria (30%) was the dominant phylum in the three libraries, followed by Gammaproteobacteria (21%) and Acidobacteria (16%). The percentages of cloned sequences with the highest similarity to reported sequences below 97 and 93% were 48.1 and 24.3%, respectively. A large number of phylotypes affiliated with bacteria that play important roles in the carbon, sulfur, and nitrogen cycles suggest an important link of bacteria to the matter cycling in these subarctic sediments.     

Data on primary production in the Bering Sea and adjacent Northern Pacific

Primary production was measured with the aid of the radiocarbon method at 112 stations in the subarctic Pacific during the decline of the spring phytoplankton maximum in late June. The ranges of integrated production under 1 m² were 0.17-4.13 g C day^-1 in the Western basin, 0.12-6.70 g C day^-1 in the shelf areas, 0.22-1.29 g C day^-1 in the central Bering Sea and 0.25-1.48 g C day^-1 in the Northern Pacific. Corresponding averages were 0.94 g C day^-1 in the Western basin, 1.55 g C day^-1 in the shelf areas, 0.72 g C day^-1 in the central Bering Sea and 0.76 g C m^-2 day^-1 in the north Pacific. At stations with surface temperatures below 5-6C, where the spring diatom 'blooms' still proceded, the phytoplankton populations were accumulating in the upper 5-15 m layer, while at stations with higher surface temperatures (>6-8°C), the phytoplankton settled down to 20-40 m together with the deepening of the upper thermocline. The assimilation numbers of chlorophyll (Chl) and specific production coefficients in the Bering Sea are given, as well as the diurnal photosynthesis curves. The aspects of annual primary production in the Bering Sea and the features of phytoplankton ecology in the subarctic Pacific are discussed.      

Genetic differentiation of Pacific cod Gadus macrocephalus in the Sea of Okhotsk and in the Bering Sea

Genetic differentiation of the Pacific cod Gadus macrocephalus was studied. Samples from six regions of the Sea of Okhotsk and the Bering Sea were analyzed with two mtDNA genetic markers-gene of cytochrome 1 and the control region (D-loop). Comparative analysis showed significant genetic differentiation between the two groups of samples. The first group included samples from Tauiskaya Bay and waters of Western Kamchatka. The second group consisted of the samples collected in the waters of the Iturup Island (Sea of Okhotsk), Northern Kurile Islands, Navarin region of the Bering Sea, and Anadyr Bay.     

Habitat and infauna prey availability for flatfishes in the northern Bering Sea

Yellowfin sole (Limanda aspera), northern rock sole (Lepidopsetta polyxystra), and Alaska plaice (Pleuronectes quadrituberculatus) are valuable flatfishes in the southeastern Bering Sea (EBS) bottom trawl fishery. The northern Bering Sea (NBS) is near their northern distribution limit. We conducted the first assessment of NBS habitat suitability for these benthivorous flatfishes from the perspective of prey availability in 2010. Benthic samples were collected at 12 trawl stations along a meridional transect extending from 60.5°N to 64.5°N east of St. Lawrence Island to characterize the prey environment. Stomach contents from the flatfishes were concomitantly collected to relate diets to prey fields. The diet compositions did not correspond spatially with the infauna communities. The flatfishes elected a prey group regardless of its relative availability. The spatial mismatch between diet and infauna compositions suggests that prey availability was high in the NBS. The flatfishes generally have versatile diets, but they were more selective of their prey here than in the EBS. The biomass and the abundance of the infauna along the transect were comparable with the EBS. Although niche overlap was high in the NBS, competition for food was likely lower than in the EBS because of the lower density of flatfish. The bottom temperatures in the NBS were in the same range as the EBS during the summer of 2010. The NBS appears to be suitable flatfish habitat at least during the summer ice-free period. The effects of climate warming on the prey environment and on the production and distribution of flatfish are complex and difficult to predict, but if the NBS were to shift over time toward milder winter conditions that more resemble the EBS, its suitability as flatfish habitat would presumably increase based on the present prey availability.     

Macromolecular production of phytoplankton in the northern Bering Sea, 2007

Photosynthetic carbon allocations into different macromolecular classes provide important clues regarding physiological conditions of phytoplankton and the nutritional status of potential grazers. The productivity experiments for photosynthetic carbon allocations were conducted at three light depths (100, 30, and 1 %) for nine different stations in the northern Bering Sea as an important gateway into the western Arctic Ocean, using the ¹³C isotope tracer technique to determine the major controlling factors and physiological conditions of phytoplankton. The photosynthetic carbon allocations into different macromolecular classes [Low molecular weight metabolites (LMWM), lipids, proteins, and polysaccharides] of primary producers were determined based on the productivity experiments. LMWM and polysaccharides had similar vertical patterns whereas lipids and proteins had reverse vertical patterns at all the stations, which is consistent with other results under different light depths. The overall average allocations were 37.9 (SD = ± 18.8 %), 26.6 (SD = ± 17.4 %), 26.5 (SD = ± 20.7 %), and 9.1 % (SD = ± 7.8 %), for LMWM, lipids, proteins, and polysaccharides, respectively. Based on a general pattern of macromolecular production in the northern Bering Sea, phytoplankton was in a physiologically transitional phase from an unlimited status to a nitrogen-deficient condition during our cruise period, 2007. However, more in situ field measurements for macromolecular production under a variety of environmental conditions will improve the understanding of the physiological responses of phytoplankton to the ongoing environmental changes in the Arctic Ocean.     

Incidence of Vibrio alginolyticus and Bacteria of Sanitary Significance in the Bering Sea

The incidence of bacteria of sanitary significance and isolation of Vibrio alginolyticus during a subtidal clam assessment study in the Bering Sea are described. Vibrio parahaemolyticus was not detected in clams, sediment, or seawater.     

Field Observations of Methane Concentrations and Oxidation Rates in the Southeastern Bering Sea

Measurements of methane oxidation rates were made in southeastern Bering Sea water samples with [¹⁴C]methane. The rate at which ¹⁴CO₂ evolved from samples exposed to one methane concentration was defined as the relative methane oxidation rate. Rate determinations at three methane concentrations were used to estimate methane oxidation kinetics. The rate constant calculated from the kinetics and the observed methane concentration in the same water sample were used to calculate an in situ methane oxidation rate and the turnover time. First-order kinetics were observed in essentially all experiments in which methane oxidation kinetics were measured. Relative methane oxidation rates were greater in waters collected at inshore stations than at the offshore stations and were greater in bottom samples than in surface samples. In most water samples analyzed, there was essentially no radioactivity associated with the cells. The resulting respiration percentages were therefore very high with a mean of >98%. These data suggest that most of the methane was used by the microflora as an energy source and that very little of it was used in biosynthesis. The relative methane oxidation rates were not closely correlated with methane concentrations and did not appear to be linked to either oxygen or dissolved inorganic nitrogen concentrations. However, there was a significant correlation with relative microbial activity. Our data suggest that the methane oxidizers were associated with the general microbial heterotrophic community. Since these organisms did not appear to be using methane as a carbon source, it is unlikely that they have been isolated and identified as methane oxidizers in the past.     

Biocenoses of Anadyr Estuary (Bering Sea) and conditions of their existence

Some bottom biocenoses in the river mouth area of Anadyr Estuary are studied. Seasonal biocenosis of filamentous algae Acrosiphonia spp. occurs in the intertidal zone, biocenosis of the bivalve Macoma balthica is common at a depth of 4–8 m. Species diversity increases with depth. The distribution of biocenoses and population structure depend on the hydrological regime and substrate type in the surveyed area.     

Ichthyofauna of Russian exclusive economic zone of the Bering Sea: 2. Ecological and zoogeographical characteristics

The ecological and zoogeographical characteristics of 344 species of Pisces and fish-like species comprising the ichthyofauna of the Bering Sea (Russian Exclusive Economic Zone) are presented for the study period of 1995?2012 (original studies) and those for previous findings in this area. The benthic species (elittoral, mesobenthic, and sublittoral; 216 species, or 62.8%) dominate if one takes into account the biotopic characteristics of the species; the majority belongs to the wide-boreal Pacific, wide-boreal Asiatic, and arcticboreal species (255 species, or 74.1%) by the zoogeographic characteristics. The comparative analysis of the fish communities of the western Bering Sea evidences to the significant changes of the ichthyofauna within the depth southwards Navarin Cape. Arctic-boreal species can be considered as a specific faunistic “margin” between the northern and the southern ichthyofauna of the western Bering Sea due to their eurybiont characteristics.     

Interannual variability in a predator-prey interaction: climate, chaetognaths and copepods in the southeastern Bering Sea

The interaction of the chaetognath Sagitta elegans with thecopepod community of the southeast Bering Sea middle shelf wasexamined in relation to environmental conditions during 1995–1999.Predation impact was estimated for 2 years, 1995 and 1997, usinggut content analysis, experimentally derived digestion time(DT) and abundances of chaetognaths and prey. Pseudocalanusconcentrations correlated with water temperature and Calanusmarshallae with sea ice extent. Sagitta elegans were less abundantbut individuals were larger in 1995, when C. marshallae predominated,compared to 1997, when Pseudocalanus and Acartia were the primaryprey. Predation by S. elegans removed <1% standing stockday^–1 of Pseudocalanus or C. marshallae in 1995 and 1.7to 2.3% of Pseudocalanus in 1997. The percent of the copepodcommunity biomass required by chaetognaths was estimated tobe <1% in 1995 compared with 8–12% in 1997. Calanusmarshallae may be more vulnerable than Pseudocalanus to cumulativepredation effects because of its reproductive strategy. Theeffect of chaetognath predation on the copepod community dependson which copepod species is predominant and its susceptibilityto cumulative predation effects, as well as on daily predationimpact, both of which varied between years with different climaticconditions.