Morphofunctional changes of the digestive gland in the bivalve mollusk Crenomytilus grayanus (Dunker, 1853) in normal conditions and after parasitic invasion by trematodes

Specifics of the digestive cycle were studied in normal individuals of Gray’s mussel Crenomytilus grayanus and in those infested by trematodes from an unpolluted area of the sublittoral zone of Peter the Great Bay in May (during the day), June, July, and August. Four types of tubules corresponding to four phases of the digestive cycle were identified, and three varieties of destructing tubules were distinguished. It was shown that normally phases of absorption and digestion prevailed in the digestive gland. The portion of absorptive tubules (type II) was 95% in spring and 79% in summer. The total portion of destructing and restoring tubules (types III and IV) did not exceed 10% in spring and 20% in summer, and portion of tubules at the initial condition (type I) was 4% in spring and 2% in summer. During the day, insignificant variations in the ratio of different type tubules were recorded. It was revealed that, normally, granulocytomes were formed during utilization of necrotic tubules. Parasitic invasion of trematodes entailed swelling of the gland and a change in the proportion of tubules: the number of absorptive tubules decreased to 20%, the number of destructing and restoring tubules increased up to 60% and 12%, respectively.     

Organochlorine Pesticides in Fishes and Mollusks from Lower Reaches of the Tumen River and of the Contiguous Part of Peter the Great Bay (Sea of Japan)

The content of persistent organochlorine pesticides (DDT and its metabolites, -, - and -isomers of hexachlorocyclohexane, HCH) were studied in the tissues and organs of some fish and molluskan species from the lower reaches of the Tumen River and the contiguous part of Peter the Great Bay (Sivuchya Bay and Zapadnaya Bay of the Furugelm Isl.) and Amursky bay. The highest total content of HCHs (785.60 ng/g of gross mass) was revealed in the digestive gland of the Japanese scallop Mizuhopecten yessoensis from Zapadnaya Bay and in the brain and the liver of the starry flounder Platichthys stellatus from the Tumen River (390.80 and 340.29 ng/g of gross mass). The maximum total content of DDT (270.70 ng/g of gross mass) was recorded in the brain of the dark plaice Pleuronectes obscurus from Zapadnaya Bay and in the liver of the far eastern smooth flounder Pleuronectes pinnifasciatus, caught in Amursky Bay to the west of Skrebtsov Isl. (212.80 ng/g of gross mass). The level of HCHs and DDT in mollusks and flounders from Zapadnaya Bay was higher than that in the same species from Sivuchya Bay. The concentration of organochlorine pesticides (OCP) in P. pinnifasciatus from the inner part of Amursky Bay at Skrebtsov Isl. was higher than in individuals of that species from the open part of the Bay at Peschany Pen. The DDT/DDE and DDT/DDT ratios evidenced the recent entry of DDT into the ecosystem of Peter the Great Bay. The southwest part of Peter the Great Bay, from the mouth of the Tumen River up to Furugelm Isl, was contaminated by HCHs to a greater extent than Amursky Bay. OCPs accumulated in appreciable quantities in the organs of fishes and mollusks of Peter the Great Bay, though their present content does not exceed sanitary–hygienic standards, a subsequent monitoring of their concentrations in biota is necessary.     

Hepatic Tumors in Flatfish from Sivuch'ya Bight (Peter the Great Bay, Sea of Japan)

The livers of six flatfish species from Sivuch'ya Bight were examined histologically for the presence of neoplastic lesions. Out of 120 fish studied, hepatic tumors were found in two individuals: the black plaice Pleuronectes obscurusand the longsnout flounderPleuronectes punctatissimus.Based on presence of tissue and cellular atypism, tumor pearls surrounded by squamous cells, and absence of mucous secretion, the neoplasm in P. punctatissimuswas classified as squamous cell carcinoma. Abnormal growth of fibrous stroma suggests a scirrhous variant of carcinoma. Tumor in P. obscuruswas classified as a hepatocellular adenoma. This is the first information on liver tumors in flatfishes of Sivuch'ya Bight.     

Reproductive function state of the scallop Mizuhopecten yessoensis Jay from polluted areas of Peter the Great Bay, Sea of Japan

The morphology of gonads and development of offspring of the scallop Mizuhopecten yessoensis sampled from six stations in Peter the Great Bay (Sea of Japan) were studied. The retardation of gametogenesis, oocytes resorption, autolysis of spermatozoa and their phagocytosis were observed in the gonads of the scallops from polluted sites. The number of hermaphrodites was about 6% against 0.3–0.4% in the scallop populations from clean areas. In the offspring development, a decrease in fertilisation success,diminution in percent of normal trochophores, D-veligers, veligers, and retardation of larval growth were recorded. The scallop populations inhabiting polluted areas of Peter the Great Bay seem to be incapable of normal reproduction. Development of offspring was a more sensitive index of disturbance of the reproductive function than morphology of scallop gonads. Analysis of the offspring development of common species of marine invertebrates is suggested to be used as a sensitive indicator of adverse environmental conditions. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.     

Bacterial communities of some brown and red algae from Peter the Great Bay, the Sea of Japan

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with thallus rot, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliphormis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.     

New species of Pogonophryne (Pisces, Artedidraconidae) from the Bellingshausen Sea, Antarctica

A new species of notothenioid fish, Pogonophryne bellingshausenensis n. sp., is described from the Bellingshausen Sea, Antarctica. The new species belongs to the dorsally-spotted “mentella” group of the genus and is characterized by having a short (about 13% SL) mental barbel with a short (about 16% of barbel length), narrow (barely wider than the stalk), and relatively inconspicuous terminal expansion composed of short, irregular, fingerlike processes. Compared to most other dorsally-spotted species of Pogonophryne (“barsukovi”, “marmorata”, and “mentella” groups), P. bellingshausenensis has a relatively wide (about 7% SL) interorbital region. An unspotted patch on the median dorsal surface of the head, posterior to the posttemporal ridges and anterior to the first dorsal fin, has not been observed previously in any dorsally-spotted species. The holotype was collected at 1,947 m, one of the deepest records for any species of Pogonophryne. A revised key to the ten species of the “mentella” group of Pogonophryne is also provided.     

Sperm ultrastructure in representatives of six bivalve families from Peter the Great Bay, Sea of Japan

The ultrastructure of sperm in seven species of bivalves, the representatives of six families, Arcidae (Anadara broughtonii, Arca boucardi), Anomiidae (Pododesmus macrochisma), Tellinidae (Macoma tokyoensis), Ostreidae (Crassostrea gigas), Myidae (Mya japonica) and Trapezidae (Trapezium liratum) is described. All the studied sperm were typical tail sperm, adapted to external insemination, which, however, had a specific structure. Differences were revealed in the form of head, acrosome structure and number of mitochondria. The studied species of the above families had their specific morphology, the Arcidae species had a bullet- or barrel-shaped head with four or five mitochondria in the middle part; the Anomiidae had conic head, the acrosome with periacrosome material and four mitochondria (a basic feature of sperm is the axial core entering periacrosome material and consisting of bundle of actin filaments); the Myidae had a curved conic head and four mitochondria; in the Tellinidae the head was bullet-shaped, the periacrosome material contained a fibril component and four mitochondria; the Trapezidae had sperm of a conic form with spherical acrosome. The spherical sperm of C. gigas were similar to sperm of Saccostrea commercialis and Crassostrea virginica, but with some distinctions in the acrosome substructure. The morphology of sperm testified to the correct attribution of the Crassostreidae family as a synonym to the Ostreidae family.     

Effects of water from Nakhodka Bay (Peter the Great Bay, Sea of Japan) on the early development of the Sea UrchinStrongylocentrotus intermedius

Our studies show that seawater from different sites in Nakhodka Bay has a deleterious effect on the development of the sea urchinStrongylocentrotus intermedius. As development proceeded to the pluteus I stage, the percentage of abnormal larvae maintained in water from Nakhodka, Novitskogo, and Vrangelya Bights increased markedly (66.7±2.2, 67.1±2.6, and 54.6±1.8%, respectively). These larvae developed more slowly, were smaller, and differed from those in the control in the intensity of color of their echinochrome granules. In water from Nakhodka and Novitskogo bights, larval survival rates were lower than in the control. This suggests that the water of Nakhodka Bay is heavily polluted, especially in its harbor areas.     

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.     

Morphological Features of Supralittoral Mollusks of the Genus Cecina (Gastropoda: Pomatiopsidae) from Peter the Great Bay, Sea of Japan

Amphibious mollusks of the genus Cecina in the littoral and supralittoral of the Sea of Japan are represented by three species: Cecina manchurica A. Adams, 1861; C. tatarica (Schrenck, 1867); and C. scarlatoi Prozorova, 1996. Additional data on the morphology of the shell and radula are provided. Indices for the identification of adult decollated and corroded shells of these species which retained only 3.0–2.5 last whorls are proposed: (1) the ratio of the width of the ultimate whorl (without aperture) to the length of the ultimate and penultimate whorls and (2) the ratio of the width of the third whorl (from the bottom) to the width of the ultimate whorl (without aperture).     

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....     

Histomorphological alterations in organs of the plaicePleuronectes obscurus from a polluted part of Peter the Great Bay, Sea of Japan

This paper describes the results of a histological study of the internal organs of the plaicePleuronectes obscurus from a polluted part of Amurskii Bay, Sea of Japan. A variety of histomorphological alterations were found in the gills and liver, while the kidney and spleen were affected to a lesser degree. The most frequent lesions in gills were edemas of gill lamellae, epithelial detachments, fusions of the secondary lamellae, hypertrophies and hyperplasias of respiratory cells, pigment accumulations, the presence of parasites, increased quantities of mucous cells, lymphocyte infiltrations, and disturbances of blood circulation. Characteristic morphological changes in the liver were lipid and hydropic dystrophy, pigment accumulation, and the presence of regenerative and necrotic foci. Telangiectasia, globate filaments, and xenomas were found in the gills ofP. obscurus for the first time. These morphological alterations appear to be a result of the chronic effect of pollution in Amurskii Bay.     

Assessment of the State of Flounders from Sivuch'ya Bight (Peter the Great Bay, Sea of Japan) Based on Histopathological Parameters

The liver and gills of five flounder species (Pleuronectes obscurus, P. punctatissimus, P. yokahamae, P. herzensteini, and Platichthys stellatus) from Sivuch'ya Bight were histologically studied. Specimens of all species were characterized by a wide spectrum of histomorphological changes. The proportions of most specific pathologies in P. obscurusfrom Sivuch'ya Bight were estimated. The pathologies comprised two major groups: those of the gills (edema and fusion of the respiratory lamellae; lifting and hyperplasia of the respiratory epithelium; vacuolization of the epithelium cells; and the presence of clavate lamellae, aneurysmal areas, and parasites) and those of the liver (vacuolization of the hepatocytes, aneurysms, necrosis of the parenchyma tissue, pathologies of the hepatocyte nuclei, pigment accumulation, and an increase in the number and size of melanomacrophage centers). The estimated proportions of pathological changes were compared with those observed in P. obscurusspecimens from the most contaminated area of Amurskii Bay. In both Sivuch'ya Bight and Amurskii Bay, the proportion of fish with various pathologies was high. The comparison of pathological changes in the gills and liver of P. obscurusand P. stellatusfrom Sivuch'ya Bight showed that, in terms of many parameters, the former species is more sensitive to pollution of the marine environment than the latter. Pathomorphological changes in the organs of the flounders studied are apparently caused by chronic pollutant action and suggest that the fish of both areas are in a damaged state.     

Fauna of Sponges (Porifera) of Peter the Great Bay,Sea of Japan

A complete list of sponges of Peter the Great Bay (northwestern Sea of Japan) is presented comprising 40 species belonging to 27 genera, 19 families, 9 orders, and 2 classes. Information is presented about the biogeographical composition of sponge fauna of the bay, the depths of their habitats, and their substrates.Original Russian Text Copyright ¢ 2005 by Biologiya Morya, Khodakovskaya.     

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     

Devonian Gastropoda from the Dornap “Massenkalk” complex (Bergisches Land,Germany)

Seven Middle Devonian (latest Givetian or earliest Frasnian) gastropod species are described from the quarry of Oetelshofen near Dornap (Bergisches Land, northwestern Rheinisches Schiefergebirge, Germany). New species areMurchisonia dornapica, Araeonema osterholzensis, Plagiothyra isekei andMacrochilina drozdzewski. Additionally, a new subspecies,Euryzone delphinuloides oetelshofensis and aNaticopsis-like species and their typical facial occurrence are discussed. The existence of predation is proved by a bore-hole inMacrochilina drozdzewski; the predator itself is not yet identified with certainty.      

Biochemical and pathogenic properties of the natural isolate of Shewanella algae from Peter the Great Bay, Sea of Japan

Pathogenic properties of the natural isolate of Shewanella algae from the coelomic fluid of the sea cucumber Apostichopus japonicus (Peter the Great Bay, Sea of Japan) were investigated. The isolate had oxydative metabolism, was positive for ornithine decarboxylase, cytochrome oxidase, catalase, DNase and gelatinase, hemolytically active, did not produce acid from carbohydrates, and did not hydrolyze urea and esculin. The strain was resistant to penicillin, amoxicillin, and ampicillin and susceptible to tetracycline and carbenicillin. Among cellular fatty acids, 13:0-i, 15:0-i, 16:0, 16:1(n-7), 17:0-i, and 17:0-ai dominated. These biochemical properties made it possible to attribute the isolated bacteria to the genus Shewanella and identified as S. algae. The cells of this bacterium were introduced into the coelomic cavity of another echinoderm, the sea urchin Strongylocentrotus nudus. As a result, in about 24 h the animals became slow and 3-8 days after the inoculation died. Dividing bacteria were being found during the experiment in the coelomic fluid as well as in the phagosomes of amoebocytes, i.e. cells acting as phagocytes in the coelomic fluid. The studies of the invasive properties of strain 156 showed that bacterial cells entered the subcuticular space of S. nudus and A. japonicus through the cuticle and stayed there for a long time without penetrating epithelium and exerting toxic effect upon the organisms of the laboratory animals. Pathogenic effect of S. algae can be manifested only if the cutaneous epithelium is destroyed permitting it to penetrate the lower tissue layers. The toxicity of S. algae is confirmed by in vitro experiments. The inoculation of the embryonic cells of S. nudus with samples of this bacterium caused the death of 10% of cells within an hour and 100% of cells within 12 h after inoculation. The results of the investigations demonstrate that S. algae could produce opportunistic infection in the sea cucumber A. japonicus and the sea urchin S. nudus, which may be natural reservoirs of this human pathogen.     

Reproduction of Snowy Sculpin Myoxocephalus brandti(Cottidae) in Peter the Great Bay, Sea of Japan

Spawning of snowy sculpin in Peter the Great Bay begins in November and takes place at a depth of about 4–7 m. Males of this sculpin species guard their laid eggs. Larvae hatch in April. Final fecundity is attained at ovary maturity stages IV–V.