Concentrations of Heavy Metals in Soft Tissues of the Gastropod Nucella heyseanain the Vicinity of Vladivostok and in the Vostok Bay Reserve

A survey was made of 168 specimens of the gastropod mollusk Nucella heyseanafrom 5 samples collected in Amurskii Bay and Vostok Bay (Peter the Great Bay and the Sea of Japan). The variability of Cu, Zn, Cd, Pb, Fe, and Mn contents in gastropod soft tissues was analyzed. The statistic concentrations of the six metals differed significantly among the samples; they were sometimes taken at a distance of a mere several tens of meters apart. N. heyseanacollected near Vladivostok generally had higher concentrations of heavy metals; however, the amount of Zn in the specimens of one sample from the Vostok Bay Reserve was 400 g/g, which is two times greater than that of mollusks from the urbanized zone. The canonical and discriminant analyses and the analysis of the variance indicate that the variation in heavy metal concentration within groups of mollusks (within bays) is comparable in magnitude with the variation among the groups.     

Arenicolous mycelial fungi from the littoral of the Vostok Bay (Peter the Great Bay,the Sea of Japan)

The taxonomic composition of marine mycelial fungi was determined in the interstitial habitats of the Vostok Bay littoral (Peter the Great Bay, the Sea of Japan). A total of 39 species of ascomycetes and anamorphic fungi were detected and identified. The predominant species of the intertidal zone were Corollospora maritima, C. lacera, Carbosphaerella leptosphaerioides, Arenariomyces trifurcatus (Ascomycota), Alternaria alternata, Scolecobasidium arenarium, and Zalerion maritimum (anamorphic fungi). The complete list of species of obligately marine ascomycetes and anamorphic fungi from the interstitial habitats of the Vostok Bay littoral is presented for the first time     

Genetic and morphological variability of the gastropod mollusk Nucella heyseana (Mollusca, Gastropoda) in the environmental optimum and pessimum

Genotypic variability at six allozyme loci and six morphological shell characters was examined in 450 individuals (four samples) of mollusk Nucella heysana from the Vrangel' Bight (Nakhodka Bay) and the Vostok Bay (Peter the Great Gulf, Sea of Japan). An analysis of variation in allele frequencies showed that each of the two localities (Vostok and Nakhodka bays) in the analyzed region is inhabited by a single, albeit genetically heterogeneous, population. A canonical analysis and an analysis of variance of individual heterozygosity (Ho) and morphological variation indicate an association between Ho and morphological variation depending on habitat (interaction) in settlements in the Vrangel' Bight and, to a lesser extent, in the Vostok Bay. These results indicate that, in extreme environmental conditions, allozyme phenotypes may be selected either themselves or as markers of genes linked with them.     

On the introduction of the ascidian <Emphasis Type="Italic">Ciona savignyi</Emphasis> Herdman, 1882 into Peter the Great Bay,Sea of Japan

The occurrence of the solitary ascidian Ciona savignyi Herdman, 1882 in Vostok Bay (Peter the Great Bay, Sea of Japan) was first documented in 2004. Adult specimens occurred in fouling communities of floating docks in Gaidamak Bay and on different anthropogenic substrates. The introduction of this ascidian into Vostok Bay is attributable to fishing ships which regularly frequent ports of Japan and to favorable environmental conditions (temperature and salinity of seawater).     

Microspatial heterogeneity of allele frequencies at allozyme loci in the bivalveMytilus trossulus: Dependence on age and depth

Allozyme variability was investigated at 18 polymorphic loci in 9 samples of the bivalveMytilus trossulus (Gould, 1850) from Vostok Bay, Sea of Japan. Significant differences in allele frequencies at some loci were found between samples from different age cohorts and different depths. Genetic distances between samples were as great as (and often exceeded) those typically found between geographically separate populations in Peter the Great Bay. Some practical recommendations for experimental researchers are proposed.     

The species composition and pattern of distribution of hermit crabs (Decapoda: Paguroidea) in Vostok Bay,Sea of Japan

The species composition, abundance, and vertical distribution of hermit crabs (Decapoda: Paguroidea) were investigated in Vostok Bay, Sea of Japan, from September 2014 to September 2015. A total of seven species from two families were found in the monitoring area of approximately 5000 m² located on the bottom within a depth range of 0–11 m: Pagurus minutus, P. proximus, P. brachiomastus, P. pectinatus, P. ochotensis, P. middendorffii (Paguridae), and Areopaguristes hirsutimanus (Diogenidae). Their population density varied from 22 ± 13 to 26 ± 2 ind./m²; the biomass varied from 55.76 ± 26.10 to 93.38 ± 27.00 g/m². The species composition remained invariable throughout the study period. The proportions of species abundance changed between seasons, as this parameter is largely determined by seasonal migrations of hermit crabs. Pagurus minutus predominated in number in winter and spring (up to 71%); P. proximus, in summer and autumn (up to 47%). In autumn and spring, P. ochotensis and P. pectinatus constituted a major part of biomass (18–25% and 19–20%, respectively). The proportion of a previously abundant species, P. middendorffii, was very small (no larger than 1.3%) during the study period. Another four species of hermit crabs occurred in other parts of Vostok Bay; thus, the fauna of the bay currently includes 11 species of this group.     

Seasonal migration promoting assortative mating in Littorina brevicula on a boulder shore in Japan

Littorina brevicula Philippi is one of the most common snails found in the upper intertidal zone of Japan. In Amakusa, some of the population of L. brevicula migrate to the lower zone in the winter, while the rest stay in the upper zone. Thus, during the winter, which is its reproductive season, the population of L. brevicula divides into two sub-populations. This leads to a hypothesis that the migration pattern in winter is genetically controlled and this behavioural dimorphism is maintained by reproductive isolation between the two sub-populations. In order to test this hypothesis, the following three points were investigated: (1) whether the same snails migrate in a similar way every winter, (2) whether there is a significant tidal level preference in snails, and (3) whether reproductive isolation occurs between the two sub-populations. The results showed (1) the migration behaviour of each snail was consistent over two successive winters, i.e. the same group of snails migrated downward every winter and the same group of snails stayed in the upper zone every winter, (2) transplanted snails moved toward the original zones where they were caught, suggesting that the snails actively selected their tidal zone in winter, and (3) most of the snails copulated within each sub-population. Therefore, reproductive isolation between the two sub-populations was considered to be established to some extent by the dimorphic migration behaviour. In conclusion, the migratory behaviour of L. brevicula is determined separately for each individual and might be genetically controlled, and the behavioural dimorphism may be maintained by partial reproductive isolation between the two sub-populations.     

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).     

Red king crab (<Emphasis Type="Italic">Paralithodes camtschaticus</Emphasis>) in the Barents Sea: A comparative study of introduced and native populations

Red king crab (Paralithodes camtschaticus) was introduced into the Barents Sea in the 1960–1970s. At present, it occurs along the coast from Hammerfest (Northern Norway) to the (northeastern coast of Kola Peninsula). We studied the polymorphism of a mitochondrial gene encoding cytochrome oxidase (COI) and five nuclear microsatellite loci in four samples from the Barents Sea and two donor populations from the Western Kamchatka and Primorye (Russian Pacifics). No decrease in the genetic diversity of the introduced populations was observed. The results of PCA103 locusanalysis but some samples from the Barents Sea significantly differed from the Pacific populations according to the test for population differentiation demonstrated that the sample from Varrangerfjord was highly significantly different from the other five populations. As no significant differences between the other samples were found at this locus. We consider it to be a marker for Varangerfjord population differentiation. Possible reasons of this phenomenon are discussed.     

Discovery of larvae of the hermit crab <Emphasis Type="Italic">Diogenes nitidimanus</Emphasis> Terao, 1913 (Decapoda: Diogenidae) in ship ballast waters: Evidence in support of its introduction into Peter the Great Bay

The larva of the hermit crab Diogenes nitidimanus Terao, 1913 was found in the ballast waters of the tanker Minotaur that arrived from the Chinese port of Laizhou (Bohai Bay, Yellow Sea). Earlier, an abundant population of mature adults of D. nitidimanus was found in Vostok Bay (Peter the Great Bay), this suggested the introduction and naturalization of this species in the Peter the Great Bay. The finding of its larva in ballast waters of a ship on the Russia-China route confirms the introduction of this species into Peter the Great Bay.     

Morphofunctional characterization of the reproductive system of the gastropods <Emphasis Type="Italic">Littorina brevicula,L. mandshurica</Emphasis>, and <Emphasis Type="Italic">Nucella heyseana</Emphasis> from uncontaminated and contaminated areas of Peter the Great Bay,Sea of Japan

The structure and state of the reproductive system were studied in the periwinkles Littorina brevicula and L. mandshurica from the coastal area of Vladivostok and in the dogwhelk Nucella heyseana from the protected area of Vostok Bay and from contaminated sites in Amursky Bay. These species were investigated for the presence of imposex and intersex (pathological changes caused by endocrine disruption under the influence of toxic substances). The pathological changes revealed in the gonads of Littorina were oocyte resorption and lipofuscin accumulation; an intersex condition was not found. Imposex specimens (with penis formation) were found among Nucella females from Amursky Bay. The relative penis length in females was 25% of the penis length in males. This kind of pathology was not found in Nucella from clean waters of Vostok Bay.     

The Structure and Density of Aggregations of the Hermit Crab <Emphasis Type="Italic">Pagurus proximus</Emphasis> Komai, 2000 in Epibiosis of the Brown Alga <Emphasis Type="Italic">Costaria costata</Emphasis> (C. Agardh) De A. Saunders, 1895 in the Sublittoral Zone of Vostok Bay,Sea of Japan

A study of epibiosis of the brown alga Costaria costata in the sublittoral zone of Vostok Bay, Sea of Japan during the spring and summer of 2016 showed that hermit crabs of the following four species accounted for approximately 85% of the total biomass: Pagurus proximus, P. minutus, P. brachiomastus, and P. middendorffii. Of these, the most abundant one (96.5% of the total number of hermit crabs) was P. proximus, the mean aggregation density of which on C. costata (429 ± 221 ind./m²) was higher by an order of magnitude than that in the adjacent area of the bouldery bottom. The size ranges of males and females of this species in aggregations on boulders and those on C. costata were similar, with a predominance of larger individuals on algae. In the size–frequency distribution, three groups of individuals corresponding to three size–age cohorts were differentiated. The male-to-female ratio was 1 : 1.7. Hermit crab aggregations on C. costata are ephemeral; their existence is determined by the duration of the period of algae development, that is, from late spring to the middle of the summer.     

Geographic variation in the growth of white croaker,Pennahia argentata,off the coast of northwest Kyushu,Japan

We examined geographic variation in the growth of white croaker,Pennahia argentata, off the coast of northwest Kyushu, Japan, Ariake Sound, Tachibana Bay, Omura Bay and the Goto Sea by examination of otoliths. The outer margins of the otoliths showed that a opaque zone was formed once a year, with its peak in June, and could be used as an annulus. White croaker caught during this study reached a maximum age of 10years in the Goto Sea. The growth curves for both sexes in all localities were expressed by the von Bertalanffy growth equations from back-calculated total length of fish. We found significant sexual differences in growth curves in Ariake Sound, Tachibana Bay and the Goto Sea. For both sexes, white croaker in the Goto Sea reached the largest length at each estimated age of the four localities. The growth curves for both sexes showed significant differences among four localities, suggesting that several stocks may exist in the study area although the greatest distance between each locality was at most 30 km.     

Genetic structure and differentiation of populations of the tetraploid species <Emphasis Type="Italic">Oxytropis chankaensis</Emphasis> (Fabaceae)

The population genetic variation of the tetraploid species Oxytropis chankaensis Jurtz. (Fabaceae), a local endemic of the western coast of Khanka Lake (Primorye), was examined. Five populations were analyzed using 28 isozyme loci encoding 16 enzyme systems. Significant allelic heterogeneity among the populations was found for six out of twelve polymorphic loci. The heterozygosity of the samples (total sample size 294 plants) H _e = 0.301 was considerable higher than the mean values in populations of endemic species (0.076). Based on the results of this study, we identified two groups of O. chankaensis populations (southern and northern), in spite of the absence of marked hiatus between them. Of special interest is the population from Przhewalski Spit, which is a natural reserve of genetic diversity of the species and the putative center of formation of the autotetraploid O. chankaensis.     

Distribution of ichthyoplankton in the eastern Peter the Great Bay,Sea of Japan,in June and July of 2007

Comparison of the results of ichthyoplankton surveys conducted at 97 stations in the eastern part of the Peter the Great Bay of the Sea of Japan, in June–July 2007 with the similar research data of the 1950s shows that at present, as was the case 50 years ago, flatfish eggs belonging mainly to the yellowfin sole Limanda aspera and brown sole Pleuronectes herzensteini prevail in the local ichthyoplankton (up to 86%). The highest concentrations of these species’ eggs were recorded in the Vostok Bay and Strelok Bay. The spawning activity of flatfish in 2007 is found to be lower than in the mid 1900s, but the significance of the eastern part of the Peter the Great Bay for flatfish reproduction remains large. The importance of long-term monitoring in this area, which is being subjected to steadily growing anthropogenic impacts, is also proven.     

Geographic Variations in Reproductive Parameters of the Starspotted Dogfish, Mustelus manazo, from Five Localities in Japan and in Taiwan

Geographic variations in reproductive parameters of Mustelus manazo from five localities, four in Japan (Aomori, Tokyo Bay, Maizuru, and Shimonoseki) and one in Taiwan, were investigated from November 1994 to June 1996. Differences in age and length at sexual maturity from Aomori to Taiwan were approximately 3 years and 300mm in TL, respectively, for both sexes. The sharks appeared to mature at a later age and to a larger size in the most northern population, Aomori, and to be faster and smaller in the southern population, Taiwan. Mating, ovulation and fertilization periods were generally during May and August in the four localities of Tokyo Bay, Maizuru, Shimonoseki, and Taiwan. In Aomori, males showed no clear monthly variation in gonad index, and females in Aomori had a protracted reproductive period. Females became pregnant every year in all localities, except Aomori. The Aomori population apparently has a different reproductive cycle. The Tokyo Bay population is distinctive regarding growth and sex ratios of embryos. In all localities, the number of embryos per litter increased relative to total length of mother. There was no geographic variation in reproductive parameters between Maizuru and Shimonoseki. The coast between these last two sampling areas is a continuous steep slope with similar environmental conditions, and mixing of the two populations may occur.     

Density Dynamics and Size Composition of Bivalve Mollusk Larvae of the Genus Mya in Peter the Great Bay (Sea of Japan)

The seasonal population size of planktonic larvae of mollusks of the soft-shell clam genus Mya were studied in Vostok Bay. The larvae occurred in plankton from the first third of June to early September. The highest density of larvae (279.7 ± 98.7 specimens/m³) was found in late June. In early July, larval numbers decreased sharply, and at the end of the first third of July, only single Mya larvae were found in the plankton. Another increase in larval population was observed in early and late August. The larvae varied in length from 175 to 325 m in June–July and from 150 to 250 m in August. It is likely that the larvae of two species of Mya, M. arenaria and M. uzenensis, are present in the plankton of Vostok Bay.     

Distribution and characteristics of <Emphasis Type="Italic">Bacillus</Emphasis> bacteria associated with hydrobionts and the waters of the Peter the Great Bay,Sea of Japan

Bacilli of the species Bacillus subtilis, B. pumilus, B. mycoides, B. marinus and B. licheniformis (a total of 53 strains) were isolated from 15 invertebrate species and the water of the Vostok Bay, Peter the Great Bay, Sea of Japan. Bacilli were most often isolated from bivalves (22.7%) and sea cucumbers (18.9%); they occurred less frequently in sea urchins and starfish (13.2 and 7.5%, respectively). Most of bacilli strains were isolated from invertebrates inhabiting silted sediments. No Bacillus spp. strains were isolated from invertebrates inhabiting stony and sandy environments. The species diversity of bacilli isolated from marine objects under study was low. Almost all bacterial isolates were resistant to lincomycin. Unlike B. pumilus, B. subtilis isolates were mostly resistant to benzylpenicillin and ampicillin. Antibiotic sensitivity of B. licheniformis strains was variable (two strains were resistant to benzylpenicillin and oxacillin, while one was sensitive). A significant fraction of isolated bacilli contained pigments. Pigmented strains were more often isolated from seawater samples, while colorless ones predominated within hydrobionts. B. subtilis colonies had the broadest range of colors. In the Bacillus strains obtained, DNase, RNase, phosphatase, elastolytic, chitinase, and agarolytic activity was detected. Bacilli strains with hydrolytic activity occurred in invertebrates more often than in seawater.