Species composition and distribution of free-living marine nematodes in Vostok Bay, Sea of Japan

The qualitative and quantitative composition of free-living marine nematodes have been studied in Vostok Bay (Peter the Great Bay, Sea of Japan). It is found that the population density of nematodes in the bottom sediments of Vostok Bay shows an uneven distribution. The mean population density equaled 56800 ± 23400 specimens/m². A correlation has been revealed between the population density of nematodes and the substrate type. Altogether, 85 species of nematodes have been found; they were dominated by Sabatieria palmaris, Rhabdodemania orientalis, Araeolaimus parvibulbosus, Oncholaimium paraolium, Doryolaimopsis peculiaris, and Metachromadora itoi. Six taxocenoses of nematodes were distinguished, taking into account the species dominating in the population density and using cluster analysis of the obtained data. The dominating trophic assemblage of nematodes was “scrapers.” In general, the species composition of nematodes in Vostok Bay is characterized by the relatively great similarity with that in other areas of Peter the Great Bay (Sea of Japan).     

Seasonal dynamics of the population density of meiobenthos in Amurskii Bay, Sea of Japan

Seasonal dynamics of population densities and the qualitative composition of meiobenthos were studied in a strait between Popova and Reineke islands in Amurskii Bay (Sea of Japan). Two peaks of population density were revealed: a spring-summer peak and an autumn peak. No correlation was found between the depth, qualitative characteristics of the ground, and population density of meiobenthos.     

Effect of the mariculture of the Japanese scallop on foraminifera assemblages in Alekseev Bight, Sea of Japan

The species composition and population densities of foraminifera were studied in scallop farming grounds in Alekseev Bight (Amurskii Bay, Sea of Japan). Ninety-one species of foraminifera were identified; members of the Elphidiidae, Discorbidae, and Ataxophragmiidae were numerically dominant. When the scallop mariculture farm was in operation, the species composition of foraminifera in farming grounds was impoverished and their population densities were an order of magnitude lower than at more distant locations. Between 1988 and 1995, after the liquidation of the farm, the species diversity and population density of foraminifera in farming grounds increased, while there was a general decline of the foraminifera population in the bay. The highest density and species diversity of foraminifera occurred on coarse silty sand and small silty pebbles, and the lowest species diversity was found on silty sediment.     

Fouling of hydrotechnical structures in western Peter the Great Bay, Sea of Japan

We studied the fouling of piers and quays in Amurskii and Pos’et bays, the Sea of Japan. The main fouling communities and groupings were identified. They were usually dominated by bivalves, the musselMytilus trossulus and the oysterCrassostrea gigas. The exotic speciesBalanus improvisus was found to naturalize in the fouling on the hydrotechnical structures of the Amurskii Bay. The qualitative composition of the fouling of the structures examined was compared using cluster analysis.     

The Meroplankton of Amurskii Bay (Peter the Great Bay,Sea of Japan)

Russian Journal of Marine Biology - The composition and seasonal dynamics of meroplankton in Amurskii Bay (Sea of Japan) were studied for the first time. The total survey period exceeded two years....     

Heavy Metals in the Tissues of Commercially Important Fish of Amurskii Bay,Sea of Japan

The concentrations of iron, copper, zinc, manganese, cadmium, and mercury in tissues and organs of Pacific herring, Far Eastern navaga, and spotted flounder from Amurskii Bay, Sea of Japan, were determined using an atom-absorption method. The distribution of these elements has been studied in organisms of the fish. The greatest concentration of iron, copper, cadmium, and mercury is found in the liver of the fish, manganese is mostly accumulated in the bone tissue, and zinc is found in the skin. Some specific features of metal accumulation in the fish of Amurskii Bay have been revealed. For example, the concentration of iron in the liver of herring and flounder significantly increased the mean concentration known from other areas. A sanitary–hygienic evaluation is provided for the recent levels of metal concentrations in these three species of commercially important fish.     

Calculation of the number of samples needed to estimate the species richness of a taxocene

A formula to calculate the area of samples that would provide the necessary level of completeness for a species richness survey of a cenosis has been deduced. The model is based on a stochastic differential equation that describes random fluctuations in species abundance and on the assumption that a Poisson distribution of individuals in space occurs. The calculations are illustrated based on the example of the littoral polychaete taxocene in Vityaz Bay of Possiet Bay of the Sea of Japan.     

The Structure of a Free-living Nematode Community in Wrangel Bay of the Sea of Japan

The qualitative composition and distribution of the meiobenthos in Wrangel Bay (Nakhodka Bay of the Sea of Japan) depend on the bottom sediment grain composition and on the concentration of heavy metals in the ground. It was established that the meiobenthos in the bay was represented by 13 groups of animals (class, order) and was relatively evenly distributed. The nematodes dominated (50–80%), and their settlement density was slightly higher in silty ground than in silty–sandy ground. Forty-eight species of nematodes were found; Dorylaimopsis peculiaris, Viscosia stenostoma, Axonolaimus seticaudatus, Metasphaerolaimus japonicus, and Pseudosteineria inaequispiclata dominated in the silty–sandy sediments; Sabatieria pulchra, S. palmaris, Metalaimus pumilus, Sphaerolaimus limosus, and Oncholaimium ramosum dominated in the silty ground. A slightly expressed correlation of the settlement density with the ground type and lead concentration in the bottom sediments emerged for two species (S. pulchra and S. palmaris).     

The species composition and quantitative distribution of the diatom genus Pseudo-nitzschia H. Peragallo, 1990 in Russian waters of the Sea of Japan and the Sea of Okhotsk

This paper studies the species composition and quantitative distribution of diatoms that belong to the genus Pseudo-nitzschia in the Russian waters of the Sea of Japan and the Sea of Okhotsk. In total, 11 species of this genus were found in the area, including 7 that are known as being potentially toxic. The highest concentrations of Pseudo-nitzschia microalgae (1.4 × 10⁶–2.7 × 10⁶ cells/L) were found in the summer and autumn in the Peter the Great Bay of the Sea of Japan and the lowest concentrations (2.5 × 10²–1 × 10⁴ cells/L) were found in the Sakhalinsky and Akademiya bays of the Sea of Okhotsk. The species diversity of potentially toxic diatoms was greatest (seven species) and the cell concentrations highest (over 6 × 10⁵ cells/L) in the Peter the Great Bay, Sea of Japan, and in the Aniva Bay, Sea of Okhotsk. The density of potentially toxic species was highest near the northeastern coast of Sakhalin Island, in the Amur River estuary, and in adjacent waters. This paper also presents geographical distribution maps of Pseudo-nitzschia species and maps of the density distribution of potentially toxic microalgae over the studied area and identifies potential amnesic shellfish poisoning areas.     

The Meiobenthos in the Area of Japanese Scallop Cultivation in Minonosok Bay (Peter the Great Bay,Sea of Japan)

In Minonosok Bay, in a region of long-term industrial mariculture of mollusks, a steady biohydrochemical complex with increased organic matter content has been formed, in which the meiobenthos community was represented by a rather complete set of taxonomic groups of low population density. There were 16 groups (order, class) of the meiobenthos revealed, and the greatest population density was recorded in the central part of the bay under installations with suspended mollusks, (333000 ind./m²). Nematodes dominated in the eumeiobenthos; however, crustaceans prevailed in the bottom water layer and sediments at stations with increased oxygen content. Bivalves and gastropods dominated in the pseudomeiobenthos. Correlation analysis has revealed the dependence of the population density of the total meiobenthos and eumeiobenthos on the type of ground. There were 42 nematode species revealed; Axonolaimus seticaudatus, Enoplolaimus medius, Daptonema sp., Paracomesoma sp., and Oncholaimium paraolium dominated. Three nematode taxocens were discriminated by dominating species in the population density and results of cluster analysis of the data. Detritivorous nematodes prevailed in all types of ground. A correlation was found between the index of species diversity of nematodes and the content of organic carbon in the ground.     

Seasonal variations of biotransformation and antioxidant parameters in liver of the smooth flounder <Emphasis Type="Italic">Liopsetta pinnifasciata</Emphasis> from Amursky Bay (Sea of Japan)

This study examines the seasonal dynamics of the activity of some antioxidant enzymes, the biotransformation enzyme glutathione-S-transferase, and levels of reduced glutathione and malondialdehyde in the liver of the flounder Liopsetta pinnifasciata from Amurskii Bay, Sea of Japan. The individual variability of biomarkers was fairly low. Significant sex differences were only found for superoxide dismutase.     

Annual Changes in Meiobenthos Community Structure in Alekseev Bight, Sea of Japan

We performed a comparative analysis of the taxonomical composition and population density of the meiobenthos and substrate types of Alekseev Bight, Sea of Japan, throughout the period when a plantation for mariculture of Japanese scallop was exploited in the bight and for a decade after the plantation had been removed. We found that silting of substrates in the bight decreased and the number of taxonomical groups that constituted the meiobenthos increased. The nematodes that, earlier, dominated the meiobenthos in terms of population density were later exceeded by foraminiferans, the species diversity of which increased. Changes are revealed in the composition of the dominant species of these groups.     

Pelagic larvae of benthic invertebrates of the Vostok Bay,peter the great bay,Sea of Japan: Composition,phenology, and population dynamics

For the first time, year round and long-term seasonal research on the composition, phenology, and population dynamics of pelagic larvae of bottom invertebrates were conducted in the Vostok Bay of the Sea of Japan. Larvae of 98 taxa of various ranks were found. The larvae of bivalves and polychaetes were the most diverse. The larvae of bottom invertebrates occurred in plankton year-round. Their density was at its minimum in January (less than 100 ind./m³), and its maximum from June to November (more than 1000 ind./m³). The larvae of polychaetes dominated in the autumn and winter seasons, whereas bivalve and gastropod larvae dominated in the spring and summer seasons. It was shown that the proportion of pollution tolerant meroplankton larvae of the Polydora and Pseudopolydora genera was high in the Vostok Bay, and could indirectly indicate increasing anthropogenic pressure in the area.     

Effect of the Razdol’naya River on structure of the free-living nematode community of the Amursky Bay,Sea of Japan

The effect of the Razdol’naya River on the littoral and sublittoral nematode community was studied in the innermost part of the Amursky Bay. Thanks to the seasonal abundance of juveniles of macrobenthic animals, pseudomacrobenthic species prevailed in the meiobenthos littoral community. Juvenile amphipods dominated (39.5%), the percentage of nematodes was 18.4% (45 species). The nematodes dominated in the meiobenthos community (65.7%, 71 species) at the sublittoral zone. The similarity of the species structure of littoral and sublittoral nematodes reached 36.5%. Low population density (2.6±1.7 thousand ind/m²) and poor species diversity of nematodes (7 species), the dominating form being Oncholaimium paraolium, were recorded at the littoral zone, which was subjected to direct riverine influence (1‰salinity). The correlation analysis revealed no relationship between salinity and population density of nematodes at the littoral zone. At the sublittoral zone (at stations of salinity less than 2.85‰) the parameters of population density (73.9±32.3 thousand ind/m²) and species diversity (12 species) of nematodes were the lowest, Parodontophora timmica dominated. A poor expressed dependence between the density of nematode populations and salinity was revealed. The correlation between the average size of ground particles and population density of nematodes was recorded. The greatest similarity of the species structure of littoral and sublittoral nematodes (26.67%) was recorded on gravel-sand bottoms.     

Development in culture of the diatomChaetoceros salsugineus from the Sea of Japan

The development of the diatomChaetoceros salsugineus from Amurskii Bay in the Sea of Japan was investigated in laboratory culture. It is shown that the intraspecific taxaC. salsugineus f.salsugineus, C. salsugineus f.curtus, andC. salsugineus f.solitarius correspond to particular stages in the development of this species in culture. Problems of the taxonomy and biology of this species are discussed. It is assumed that the life cycle ofC. salsugineus includes a benthic stage represented by resting cells.     

Retrospective analysis of the marine flora of Vostok Bay,Sea of Japan

A general list of the flora of Vostok Bay (Sea of Japan) compiled on the basis of original and literature data includes 161 species, among them 25 green algae, 42 brown algae, 90 red algae, and 4 species of seagrass. In the period from 2000 to 2004, 114 species of macrophytes (19 green algae, 29 brown algae, 63 red algae, and 3 species of seagrass) were found in Vostok Bay; 19 species of algae were first records for this bay. On the whole, the flora of Vostok Bay is dominated by warm-water species, among which Asian low-boreal species occupy the leading position. The flora of Vostok Bay is changing under the influence of global climatic and local anthropogenic factors. In recent years, there is a tendency for the proportion of warm-water species to increase. The local anthropogenic influence on the flora of Vostok Bay has caused changes in the species composition of plant communities.