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).     

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.     

Recreational Effects in Vostok Bay, Sea of Japan

The paper presents the results of three hydrochemical surveys performed in October 2000 and May and July 2001 and microbiological monitoring performed in June, July, and August 2001 in Vostok Bay (Sea of Japan), which is a favorite recreation area for the inhabitants of Primorye and the Russian Far East. It is shown that at the height of recreation occurs during late summer, as determined by the concentration of water-dissolved oxygen, the biochemical oxygen demand (BOD₅), the concentration of detergents, and the number of colony-forming enterobacteria in 1 ml of water. However, in autumn, especially by October, the anthropogenic pressure decreases and the quality of the water environment in the bay improves.     

Fauna of Sipunculans (Sipuncula) of Vostok Bay, Sea of Japan

Fauna and systematics of sipunculans inhabiting Vostok Bay, Sea of Japan, are discussed. A revision of the local species of sipunculans is performed for the first time. On the basis of study of outer and inner morphology, some species are reduced to synonyms. Extended diagnoses are proposed for all registered species. An identification key is presented for the sipunculans of Vostok Bay.     

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     

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.     

The distribution, size and age compositions, and growth of the scallop Mizuhopecten yessoensis (Bivalvia: Pectinidae) in the northwestern Tatar Strait

The distribution patterns, size, age structure, and growth of the scallop Mizuhopecten yessoensis were studied in the northwest of the Tatar Strait, Sea of Japan. We determined that the northern boundary of the species range occurred in the region of Tabo Bay, at 51°37?? N. The distribution of the mollusk, depending on latitude, depth, substrate, and age, was determined. The maximum depth of M. yessoensis habitat is 138 meters, the maximum shell height is 200 mm, and the maximum age is 14 years. The differences in the growth rate of the Japanese scallop in different areas are discussed in relation to the conditions of its habitat in the northern part of its range.     

Some Data on the Composition and Distribution of the Meiofauna in Vostok Bay (Sea of Japan)

The effect of some environmental factors on the composition and spatial distribution of the meiobenthos were studied in Vostok Bay. The spatial density of the meiobenthos significantly positively correlated with ground type and was maximum in fine- grained sands. The eumeiobenthos was dominated by harpacticoids in coarse-grained ground and by nematodes in ground with a high silt content. The pseudomeiobenthos was dominated by polychaetes and bivalve mollusks in all ground types. The depth distribution of the meiobenthos was highly heterogenous, harpacticoids being the only group whose distribution correlated significantly with depth.     

Trophic Assemblages of the Rocky Intertidal Zone in Vostok Bay,Sea of Japan

The ratios between the indices of relative abundance for different trophic life forms have been used to characterize bionomical types of a rocky intertidal zone. It has been shown that the distribution of life forms is determined by the geomorphological peculiarities of the surveyed intertidal areas. A brief critical historical review has been provided of the terms bionomy and bionomical type.     

Reappearance of Eumarcia fumigata (G.B. Sowerby II, 1853) (Bivalvia: Veneridae) into the Swan River,Western Australia

ABSTRACT

The venerid bivalve Eumarcia fumigata was a common species in Western Australia (WA) during the Pleistocene, where it was distributed as far north as Shark Bay. It became extinct in WA as the climate changed several thousand years ago but remains common in eastern Australia from southern Queensland to South Australia and Tasmania. The species has recently reappeared in the Swan River, probably due to shipping movements. Of the > 60 marine and estuarine species introduced into WA it is only the third confirmed introduction from eastern Australia, and the first that is a reappearance in the Swan River of a species present in the geological past. The present reappearance of E. fumigata, and the introduction of other species, has been made possible by the removal of a rocky bar at the mouth of the estuary and the creation of more marine conditions in the lower Swan estuary.     

Growth and Longevity of the Gastropod Nucella heyseana in Vostok Bay,Sea of Japan

Features of the morphology, longevity, and growth of the gastropod mollusk Nucella heyseana collected in different seasons in 2000–2001 in Vostok Bay (Sea of Japan) were investigated. Shell surface features such as grooves and spurs of the axial sculpture have proven to be unhelpful in the estimation of individual age and growth rate of this species. Concentric rings on the outside of the operculum formed yearly in the cold season are useful for these purposes. The longevity of N. heyseana in southern Primorye is 10 years; this value is similar to the life span of mollusks from the southern Kuril Islands. Local differences in longevity, growth allometry, and age changes in the body size and mass of N. heyseana in relation to habitat conditions are discussed.     

The Parasitic Fauna of Common Species of Hermit Crabs of Vostok Bay (Sea of Japan)

The parasitic fauna of common species of hermit crabs was investigated in Vostok Bay (the northwestern Sea of Japan). Pagurus proximus and Areopaguristes hirsutimanus had no parasites. The average prevalence of rhizocephalan infestation in other five species of hermit crabs ranged from 5.67 to 20.83%. The prevalence of the isopod Parapseudione lata on hermit crabs did not exceed 1%, the prevalence of infestation with the isopod Athelges takanoshimensis was significantly higher, reaching 14.58% in Pagurus middendorffii. Parasitism by the isopod P. lata on the hermit crabs Pagurus minutus and P. ochotensis, as well as parasitism by the rhizocephalan Peltogaster reticulata on P. minutus were recorded for the first time. Several variants of simultaneous infestation with two parasitic species were found. The decline in the abundance of P. middendorffii accompanied by the high prevalence of parasites, primarily the colonial rhizocephalan Peltogasterella gracilis, suggests that parasite invasion may play a more significant role in regulating the abundance of hermit crabs than was previously assumed.     

The Karyotype of the flathead sculpin Megalocottus platycephalus taeniopterus (Kner, 1868) (Pisces: Cottidae) from Vostok Bay,Sea of Japan

For the first time, we studied the karyotype of the flathead sculpin Megalocottus platycephalus taeniopterus (Kner, 1868) from Vostok Bay of the Sea of Japan. The karyotype is stable: 2n = 42 (2 metacentric, 2 submeta-subtelocentric, 30 subtelocentric, and 8 acrocentric chromosomes), NF = 44 + 2. The nucleolar organizers (NOs) were identified using Ag banding in two pairs of chromosomes: in the telomeric parts of the short arm of the medium-size subtelocentric chromosome and the long arm of the large acrocentric chromosome. Variations in the number of nucleolar organizer chromosomes and in the number of NO staining blocks were found. Comparison of the karyotypes of M. p. taeniopterus and previously studied M. p. platycephalus (Pallas, 1814) from the northern Sea of Okhotsk revealed their similarity in the number and morphology of chromosomes and the number of chromosome arms and difference between the subspecies in the number and location of NO, which allows their discrimination.     

Reproduction and larval development of the gastropodAlaba vladivostokensis in Vostok Bay, the Sea of Japan

The reproduction and development of the prosobranch gastropodAlaba vladivostokensis Bartsch were studied. In Vostok Bay,A. vladivostokensis reproduces in the warmest season at water temperatures of 19–23°C. The females lay egg masses in the shape of flat, coiled bands on eelgrass leaves and on sargosso thalluses. The total period of development from egg laying to larval settling takes 25–27 days. The reproduction and development patterns and larval morphology ofA. vladivostokensis are similar to that ofAustralaba picta (A. Adams), which inhabits the coast of Japan. It is suggested that the population ofA. vladivostokensis in Peter the Great Bay should considered as part of the wide geographical range ofA. picta.     

Monitoring of phytoplankton in the area of a sea farm in Vostok Bay (Sea of Japan)

The qualitative and quantitative composition of phytoplankton in the area of a sea farm in Vostok Bay (Sea of Japan) was investigated from July 2001 to May 2002. The overall numbers of phytoplankton were 0.008 to 5.3 million cells/liter, and the biomass was 0.02 to 20.5 g/m³. The maximum density and biomass of phytoplankton were observed in summer, fall, and winter. Ten species known to be toxic were recorded. Of these, Pseudo-nitzschia multiseries (Hasle) Hasle, Alexandrium acatenella (Whedon et Kofoid) Balech, and Chattonella marina (Subrahmanyan) Hara et Chihara were found in Vostok Bay for the first time. For the diatom Skeletonema costatum (Greville) Cleve, which is an indicator of extremely eutrophic waters, the cell density was positively correlated with the area of the culture site.Original Russian Text Copyright © 2005 by Biologiya Morya, Morozova, Orlova.     

Subtidal macrobenthos communities of Vostok Bay (Sea of Japan) under conditions of anthropogenic impact

Quantitative samples of the macrobenthos were collected in May, July, and October–November from 2000 to 2002 in Vostok Bay, Sea of Japan. The main characteristics of the subtidal macrobenthos communities are described. The present study shows that the rocky bottom communities of Vostok Bay have changed little over the past 30 years. Changes have occurred in the structure of soft bottom communities and phytocenoses. Analysis of the macrophytes species composition and the value of the floristic coefficient suggest a currently moderate anthropogenic load on Vostok Bay.Original Russian Text Copyright © 2004 by Biologiya Morya, Galysheva.     

Vertical Distribution of the Far East Trepang Apostichopus japonicusin Vostok Bay,Sea of Japan

The abundance, weight, and age structure of aggregations of the Far East trepang Apostichopus japonicuswere studied in Vostok Bay, Sea of Japan, during the first part of September 2000. The highest density of aggregations (8.3 ± 0.5 ind/m²) and biomass (131.88 ± 10.50 g/m²) of animals was characteristic for coastal sites at the depth 0.5–1.5 m. With anincrease in depth the biomass and density of A. japonicusreduced 1.5 and 3 (depth 5–6 m), 220 and 830 times (depth 8–15 m) respectively. The ratio of large animals concurrently increased in the aggregation structure. The specifics of the distribution and spatial variability of the aggregation structure are discussed in relation to uncontrolled fishing of holothurians of large sizes.     

Population dynamics of Megapitaria squalida (Bivalvia: Veneridae) at Magdalena Bay, Baja California Sur, Mexico

The population dynamics of an intertidal population of Megapitaria squalida was studied from September 2002 to February 2003 in Bahia Magdalena, Mexico. To obtain information about the artisanal and recreational fishery of M. squalida, local fishermen at different parts of the bay were interviewed. Clam densities were determined at one unexploited and two exploited sites along perpendicular transects from the shore line. Average clam density was 2.01+/-1.41 ind/m2, densities did not differ significantly between the three sampling sites. The length-total mass relation was Mtot = 0.0001*SL3.1644 (r2 = 0.9804, n = 92) and the length-tissue mass relation was Mtis = 0.0002*SL2.7144 (r2 = 0.945, n = 92). Von Bertalanffy-growth parameters were determined using marked individuals. Strong interindividual and also seasonal differences in growth were observed. Average annual values were: K = 0.655, Linfinity = 83 mm. Since M. squalida can reach a shell length of more than 135 mm in deeper waters, it is necessary to consider intertidal and subtidal populations separately. Average total mortality (Z) was 1.61 y(-1). No fishing mortality was calculated because total mortality Z at the unexploited control site was higher than Z at the exploited sites. It appears that M. squalida migrates into deeper water with increasing shell length, as average shell length increased at lower tidal levels and marked specimens showed a clear migration towards deeper waters. As yet no overexploitation could be found in the study area.     

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....     

Age and growth in three populations of Dosinia exoleta (Bivalvia: Veneridae) from the Portuguese coast

The present study aimed at estimating the age and growth in three populations of Dosinia exoleta from the Portuguese coast (Aveiro in the north, Setúbal in the southwest and Faro in the south). Two techniques were compared to ascertain the most suitable method for ageing D. exoleta. Growth marks on the shell surface and acetate peel replicas of sectioned shells were the techniques applied. Two hypotheses were tested: growth parameters present latitudinal variation along the Portuguese coast; growth parameters are influenced by the fishing exploitation. Shell surface rings proved inappropriate for ageing this species, whereas acetate peels provided realistic estimates of the von Bertalanffy growth parameters (K, L _∞ and t ₀). A latitudinal gradient in growth rate was detected, with a clear southward increase in the growth coefficient (K) of D. exoleta (Faro > Setúbal and Aveiro) indicating that warmer waters in southern Portugal provide optimal conditions for the growth of this species. Fishing exploitation in northern Portugal targets larger individuals and leaves behind a younger population of smaller individuals, decreasing the asymptotic shell length (L _∞ ) of D. exoleta from Aveiro. The overall growth performance was compared among populations of D. exoleta and with other venerid species worldwide.