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.     

Distribution of cephalopods in the upper epipelagic northwestern Bering Sea in autumn

In the northwestern Bering Sea in autumn, the epipelagic cephalopod community was represented by the boreal fauna, and was found to be composed of three families and nine species of the order Teuthida: Gonatidae (Berryteuthis magister, Boreoteuthis borealis, Gonatopsis japonicus, Gonatus madokai, Gonatus kamtschaticus, Gonatus onyx, and Gonatus pyros), Chiroteuthidae (Chiroteuthis calyx) and Onychoteuthidae (Onychoteuthis borealijaponica). Two pelagic gonatid species (B. borealis and G. kamtschaticus) dominated the cephalopod community in the upper 50 m. The distribution patterns of B. borealis and G. onyx were associated with diel vertical migrations of these squid. The distribution of two distinct size groups of G. kamtschaticus suggested ontogenetic migration of larger squid to deeper layers, and adds to previous data suggesting that this species may be a heterogeneous assemblage. Demersal B. magister rarely occurred in the surface waters. The occurrence of maturing O. borealijaponica in the southern marine area indicated that these were occasional seasonal migrants from the ocean. The occurrence of juvenile C. calyx suggested that these squid may conduct vertical forage migrations from deep waters to the surface layers.     

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.      

New Data on Soft Sculpin Malacocottus zonurus (Psychrolutidae) from the Northwestern Bering Sea

Journal of Ichthyology - Biological features of soft sculpin Malacocottus zonurus (Psychrolutidae) are described based on the analysis of samples from bottom trawl catches in the northwestern...     

Distribution and some features of biology of representatives of the genus Lycodes in the western part of the Bering Sea in the summer period

Based on materials of bottom inventory trawl survey performed in summer 2008 in the western part of the Bering Sea, we show that representatives of the genus Lycodes in the summer period occur almost throughout the study water area of the sea from the sublittoral to the drop-off. The pattern of distribution and abundance of particular species depend on the depth and specific features of the hydrological regime of the given area. The most numerous species??Lycodes brevipes and L. palearis??are found in warm intermediate and in cold demersal water masses, are distributed over a vast stretch, and there form considerable concentrations. Deep-water species??L. beringi and L. concolor??are more stenothermal, occur along the narrow band of the continental slope, and are considerably inferior to stretch species in numbers. Of shallow species dwelling at depths smaller than 100 m, only L. raridens has high numbers and occurs over a considerable area in the northern part of the study area, the remaining species (L. mucosus, L. polaris, and L. turneri) are caught in small amounts at local sites. The largest sizes are in L. raridens and L. concolor, their maximum length in catches is more than 70 cm, the former species reaches maximum length in the seventh year of life, and the latter reaches maximum length in the ninth year. The smallest and slowest-growing among the studied fish is L. brevipes: its maximum length in catches does not exceed 39 cm and maximum age is 7 years.     

楚科奇海及白令海大型底栖生物初步研究

1999年夏季在楚科奇海、白令海采用30 cm×30 cm箱式取样器,取得16个站位大型底栖生物定量样品。经分析研究有大型底栖生物92科164种,其中多毛类、软体动物和甲壳动物种数最多,占总种数的88.41％,三者构成北极楚科奇海和白令海大型底栖生物的主要类群。优势种有独毛虫属一种(Tharyx sp.) 、齿吻沙蚕属一种(Nephtys sp.)、囊叶齿吻沙蚕(Nephtys caeca)、平滑胡桃蛤(Ennucula tenuis)、短吻状蛤(Nuculana pernula pernuloides)、拟猛钩虾属一种( sp.)、日本沙钩虾(Byblis japonicus)和萨氏真蛇尾(Ophiura sarsii)等。楚科奇海和白令海大型底栖生物平均生物量为111.83 g/m²,平均栖息密度为2538个/m²。生物量和栖息密度均以多毛类和软体动物占多数。楚科奇海和白令海大型底栖生物有5个群落类型：Ⅰ. 梯额虫(Scalibregma inflatum)-紫轮参(Polycheira rufescens)-结栉盖蛇尾(Stegophiura nodosa)群落, Ⅱ. 拟单指虫(Cossurella sp.)-平滑胡桃蛤-鳞甲钩虾(Lepidepecreum sp.)群落, Ⅲ. 缩头竹节虫(Maldane sarai)-葛氏希泊钩虾(Hippomedon gorbunovi)-萨氏真蛇尾群落, Ⅳ.齿吻沙蚕(Nephtys sp.)-平滑胡桃蛤-日本沙钩虾-戈芬星虫(Golfingia sp.)群落和白令海群落, 即索沙蚕(Lumbrineris fragilis)-户枢蛤(Asthenothaerus sp.)-太平洋方甲涟虫(Eudorella pacifica)-革囊星虫(Phascolion sp.)群落。楚科奇海的群落Ⅰ、群落Ⅱ和白令海各群落结构相对稳定;楚科奇海群落Ⅲ和群落Ⅳ出现一定扰动。     

Morphology and biology of cystophorous cercariae from the Bering sea]

Three new species of cystophorous cercariae, Cercaria appendiculata Pelseneer, 1906, C. octocauda Tschubrik, 1952 and C. saccocaudata Tschubrik, 1966, are described from the gastropod Tectonatica clausa (Broderip et Sowerby). C. saccocaudata is a larva of trematodes of the genus Lecithaster. The development of parthenites of this species carries out within one summer season. Parthenites of C. appendiculata and C. octocauda are capable to survive unfavourable winter conditions and produce cercariae in the next summer. The above three species were found to eject cercariae through the ejaculatory tube which is an important adaptation of chemiurids to the infection of the second intermediate hosts.     

New data on the Blue-Eyed Searcher <Emphasis Type="Italic">Bathymaster signatus</Emphasis> (Bathymasteridae,Perciformes) from the northwestern part of the Bering Sea

Special traits of the biology of the Blue-Eyed Searcher Bathymaster signatus are considered on the basis of bottom trawlings in the northwestern part of the Bering Sea in July 2000 at depths of 136–400 m. Its spawning ends in June. Maturation occurs at the length of 27–28 cm. Individual absolute fecundity is 90 351 eggs, the diameter of oocytes is 1.4 mm, and the weight is 1.14 mg. The diet consists mainly of polychaetes followed by (according to significance) hermit crabs, shrimps, and gammarids.     

Density and distribution of bacterioplankton and planktonic ciliates in the Bering Sea and North Pacific

The total number of planktonic bacteria in the upper mixed layerof the Bering Sea during the late spring-early summer periodranged between 1 and {small tilde}4 x 10⁶ ml^–1 (biomass10–40mg C m^–3). In the northern Pacific, along 47–52⁶N,the corresponding characteristics of the bacterioplankton densityin the upper mixed water layer were: total number 1–2x 10⁶ cells ml^–1 and biomass 15–46mg C m^–3Below the thermocline at 50–100 m, the density of bacterioplanktonrapidly decreased. At 300 m depth, it stabilized at 0.1–0.2x 106 cells ml^–1. The integrated biomass of bacterioplanktonin the open Bering Sea ranged between 1.2 and 3.6 g C m^–2(wet biomass 6–18 g m^–2) Its production per dayvaried from 2 to 23 mg C m^–3 days^–1 in the upper0–100 m. The numerical abundance of planktonic ciliatesin this layer was estimated to be from 3 to l0 x 10³ cells l^–1,and in the northern Pacific from 0.4 to 4.5 x 10³ l^–2.Their populations were dominated by naked forms of Strombidium,Strombilidium and Tontonia. In some shelf areas, up to 40% ofthe total ciliate population was represented by the symbioticciliate Mesodinium rubrum. The data on the integrated biomassof basic groups of planktonic microheterotrophs are also presented,and their importance in the trophic relationships in pelagiccommunities of subarctic seas is discussed.     

New data on rex sole <Emphasis Type="Italic">Glyptocephalus zachirus</Emphasis> (Pleuronectidae) in the northwestern part of the Bering Sea

The data on the size composition, the organ system indices, and the spatial distribution of the rex sole Glyptocephalus zachirus in the northwestern part of the Bering Sea for June–August 2000 has been reported.     

Species abundance and ichthyofaunistic zoning of pelagial of the northwestern part of the Sea of Japan

Having evaluated data collected by the TINRO Center for a period of 23 years on the distribution of pelagic ichthyofauna, conclusions regarding the ichthyofaunistic zoning of the northwestern part of the Sea of Japan are here presented. Areas presenting the most dramatic changes in abundance and variety of species delineate 12 basic ichthyofaunistic zones whose species-clustering information, when examined in its entirety, clearly reveals the state of the faunistic province of the northern Sea of Japan.     

Reproductive biology of skates, Bathyraja(Ishiyama), along the eastern Bering Sea continental slope

Eight Bathyraja skate species, Bathyraja aleutica, Bathyraja interrupta, Bathyraja lindbergi, Bathyraja maculata, Bathyraja minispinosa, Bathyraja parmifera, Bathyraja taranetzi and Bathyraja trachura, collected along the eastern Bering Sea continental slope were examined for reproductive features. The sex ratio for six of eight Bathyraja skate species studied was c. 1 : 1 with males dominating for B. interrupta and B. parmifera. Five of eight species examined, B. aleutica, B. lindbergi, B. parmifera, B. taranetzi and B. trachura approximately equalled or exceeded the maximum reported total length, L_T. Maximum L_T for three species (B. interrupta, B. minispinosa and B. parmifera) revealed that the largest individuals were males and that in three other species (B. lindbergi, B. maculata and B. trachura) both females and males grew to approximately the same size. Both females and males matured at approximately the same L_T for seven of eight species. Only female B. aleutica matured at a much larger size than males. All species matured within a narrow size range following a protracted juvenile stage and once mature these skates appeared to grow very little. First maturity for all species occurred at ≥80% of their maximum L_T. The number of oocytes did not significantly differ between the left and right ovary for any species. The total number of mature oocytes increased with L_T for six of eight species examined. The number of oocytes for one species, B. aleutica, increased in number until 145 cm L_T, then declined in those individuals greater in length. The egg cases of all species are described, of which four (B. lindbergi, B. parmifera, B. taranetzi and B. trachura) have never been previously reported. Evidence is presented that suggest skates may be limited to as little as one and as many as 13 spawning seasons, depending on the species, and that senescence may occur in older individuals.     

Abundance and distribution of toxic Alexandrium tamarense resting cysts in the sediments of the Chukchi Sea and the eastern Bering Sea

Abundance and distribution of the toxic dinoflagellate Alexandrium tamarense species complex resting cyst were investigated in the eastern Bering Sea and the Chukchi Sea for the first time. Sediment samples (top 0–3 cm depth) were collected from the continental shelf of the eastern Bering Sea (17 stations) and the Chukchi Sea (13 stations) together with a long core sample (top 0–21 cm depth) from one station in the Chukchi Sea during 2009–2012. The cysts were enumerated using the primuline staining method. Species identification of the cysts was carried out with multiplex PCR assay and the plate morphology of vegetative cells germinated from cysts in the both areas. Alexandrium cysts were widely detected in the both areas, ranging from not detected (<1 cysts cm⁻³) to 835 cysts cm⁻³ wet sediment in the eastern Bering Sea and from not detected (<1 cysts cm⁻³) to 10,600 cysts cm⁻³ in the Chukchi Sea, and all isolated cysts were genetically and morphologically identified as the North American clade A. tamarense. Their cysts were mainly distributed in the shallow continental shelf where the water depth was less than 100 m in both areas. The cysts were detected from the deep layer (18–21 cm depth of sediment core) of the long core sample. The present study confirmed the abundant existence of A. tamarense with wide range of distribution in these areas. This fact suggests that A. tamarense vegetative cells have appeared in the water column in the both areas. Furthermore, these abundant cyst depositions indicate that this species originally distributed in the Arctic and subarctic regions and well adapted to the environments in the marginal ice zone.     

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...     

Distribution and some biological features of Lycodes raridens (Zoarcidae) in the western part of the Bering Sea

Based on a bottom trawl survey, it is shown that in Karaginskii and Olyutorskii bays of the western part of the Bering Sea, Lycodes raridens is a typically elittoral species, since it was recorded at depths of 52–120 m, and the majority of individuals of this species were found in the range of depths 50–100 m. The maximum concentrations of Lycodes raridens were 139 ind./km² or 98 kg/km², whereas the average values of the distribution density of this species were 7.8 ind.km² or 5.4 kg/km². In Karaginskii and Olyutorskii bays, Lycodes raridens is represented by individuals with a length of 16–86 cm, weight of 34–4510 g, at the age of 1+ to 7+, although fish with a length of 30–50 cm, weight of 100–1000 g, and age of 3+–4+ dominate. The data obtained suggest that in the autumn or autumn-winter period, the study species spawns in the western part of the Bering Sea. The dominant food of Lycodes raridens here are amphipods, polychaetes, bivalves, and decapods; by occurrence and the relative content in the stomach (% of weight), amphipods (as a rule, Melita spp.) and bivalves (Yoldia spp. and Macoma sp.) dominate. Lycodes raridens is a benthophage in which, at the early stage of the life cycle, gammarids prevail in food; with growth, its diet becomes more diverse due to bivalves, polychaetes, and decapods.     

Phytoplankton distribution patterns in the northwestern Sargasso Sea revealed by small subunit rRNA genes from plastids

Phytoplankton species vary in their physiological properties, and are expected to respond differently to seasonal changes in water column conditions. To assess these varying distribution patterns, we used 412 samples collected monthly over 12 years (1991–2004) at the Bermuda Atlantic Time-Series Study site, located in the northwestern Sargasso Sea. We measured plastid 16S ribosomal RNA gene abundances with a terminal restriction fragment length polymorphism approach and identified distribution patterns for members of the Prymnesiophyceae, Pelagophyceae, Chrysophyceae, Cryptophyceae, Bacillariophyceae and Prasinophyceae. The analysis revealed dynamic bloom patterns by these phytoplankton taxa that begin early in the year, when the mixed layer is deep. Previously, unreported open-ocean prasinophyte blooms dominated the plastid gene signal during convective mixing events. Quantitative PCR confirmed the blooms and transitions of Bathycoccus, Micromonas and Ostreococcus populations. In contrast, taxa belonging to the pelagophytes and chrysophytes, as well as cryptophytes, reached annual peaks during mixed layer shoaling, while Bacillariophyceae (diatoms) were observed only episodically in the 12-year record. Prymnesiophytes dominated the integrated plastid gene signal. They were abundant throughout the water column before mixing events, but persisted in the deep chlorophyll maximum during stratified conditions. Various models have been used to describe mechanisms that drive vernal phytoplankton blooms in temperate seas. The range of taxon-specific bloom patterns observed here indicates that different ‘spring bloom'' models can aptly describe the behavior of different phytoplankton taxa at a single geographical location. These findings provide insight into the subdivision of niche space by phytoplankton and may lead to improved predictions of phytoplankton responses to changes in ocean conditions.     

Length–weight relationships of deep-sea fishes from the western Bering Sea

Length–weight relationships are lacking for most deep-sea fishes. This study presents length–weight relationships for 42 species from the western Bering Sea. Results show significantly different relationships between females and males for 11 species and between juveniles and adults of four species. A plot of length–weight estimates, log a over b , showed the deep-sea fishes in this study to be more of the elongated shape compared with other marine fishes.