Distribution Pattern of Far Eastern Sea Cucumber Apostichopus japonicus in Busse Lagoon (Southern Sakhalin)

We analyzed the distribution pattern and size structure in aggregations of the far eastern sea cucumber (trepang), Apostichopus japonicus in Busse Lagoon (Southern Sakhalin). Trepang populations, which differ in their size composition and population density, have been grouped by their spatial differentiation. It has been shown that in the absence of solid substrates in the lagoon, the animals gather on substrates such as the alga Ahnfeltia tobuchiensis and on clusters of the oyster Crassostrea gigas. It is found that on the southeastern part of the lagoon, trepang makes up an extensive aggregation confined to the bed of Ahnfeltia; the distribution of the holothurians mostly has a random pattern. In the northwestern part of the lagoon, trepang makes up aggregations on oyster and algal beds; the distribution of these aggregations shows a random pattern.     

Impact of Polluted Bottom Deposits on the Species Structure and Abundance of Bivalves in Peter the Great Bay,Sea of Japan

Data from long-term (1979–1988) studies of bivalve fauna and of the content of priority pollutants in the bottom deposits of Peter the Great Bay have been analyzed. It was established that the biomass, population density, number of species, and the species diversity indexes of Shannon-Weiner and of the Pielou evenness of bivalves negatively correlated with the total pollution factor, TPF, of bottom sediments. Changes in the ecological parameters of bivalves with an increase in pollution occurred in spurts within the 3.4–3.6 interval of TPF values. The area of such values covered not only the coastal zone of Vladivostok, but also a considerable part of Amursky Bay.     

The Status of the Pacific Oyster,Crassostrea gigas (Thunberg, 1793), Population in the Busse Lagoon,Sakhalin Island

Russian Journal of Marine Biology - The status of the aggregation of the Pacific oyster Crassostrea gigas (Thunberg, 1793) in the Busse Lagoon (Sakhalin Island) was assessed in 2019. The...     

Larvae of phoronids (Phoronida) from Terpeniya Bay (Southeastern Sakhalin)

Phoronid larvae were found in planktonic samples from the northern coast of Terpeniya Bay. In some samples, their density was up to 220 specimens/m³. Larval stages having 10, 12, 16, 20, and 22 tentacles are described. Larvae were identified as Actinotrocha branchiata and belong to the species Phoronis muelleri Selys-Longchamps, 1903. However, unlike the Ph. muelleri larvae described in the literature, the larvae we found are smaller (not more than 900 μm) before metamorphosis and have fewer tentacles (24). They lack paired vacuolated diverticula of the stomach, which are characteristic of Ph. muelleri larvae. However, judging by all other characters, namely transparency, the absence of coelomic cylinder in the preoral lobe, and the presence of adult tentacle primordia, one pair of blood cell aggregations, and a pyriform organ, these larvae are similar to the previously described larvae of Ph. muelleri. Adult forms of Ph. muelleri were previously found in Terpeniya Bay and described by Mamkaev (1962) and Emig (1984).     

Intertidal Communities of Severnyi Bay (Northern Sakhalin Island)

The paper describes the composition, structure and vertical distribution of intertidal communities in Severnyi Bay (the northern extremity of Sakhalin Island).     

Pelagic larvae of Ventrifossa garmani (Gadiformes: Macrouridae) from Suruga Bay and offshore waters of Japan

Three pelagic larvae [5.1–5.9 mm in head length (80+ to 101+ mm in total length)] of a macrourid fish, Ventrifossa garmani, from Suruga Bay and offshore waters of central Japan are described. The specimens were characterized by a remarkably elongate caudal region (caudal region length >15.6 times head length), the longest known to date among macrourid larvae and juveniles. Other characteristics included a short snout, first dorsal and pelvic fin rays not elongated, external melanophores on most of the body and posteriorly on the anal fin membrane, and six or seven rectangular clusters of internal melanophores laterally on the anterior caudal region.     

Reproduction of Pacific Salmon (Oncorhynchus) in Rivers Flowing into Terpeniya Bay (Sakhalin Island)

Journal of Ichthyology - The conditions for the reproduction of Pacific salmon of the Oncorhynchus genus in rivers flowing into Terpeniya Bay were assessed. The differences between the rivers of...     

Abundance and spatial distribution of sympatrically breeding Catharacta spp. (skuas) in Admiralty Bay, King George Island, Antarctica

We examined the abundance and spatial distribution of sympatrically breeding skuas (Catharacta spp.) within Admiralty Bay, King George Island, Antarctica, during the austral summer of 2004/2005 in relation to spatial variables, which correspond to access to resources and nesting site safety and quality. We also compared the distribution and abundance of skua pairs observed in 2004/2005 to published skua census data from 1978/1979. Similar to previous studies, we found that brown skua (C. antarctica lonnbergi) pairs often nested in close proximity to penguin colonies and actively excluded other pair types from having direct access to penguin resources. In areas directly around penguin colonies, brown skua displace south polar skua (C. maccormicki) and other pair types, indirectly forcing them to nest in possibly lower quality territories, which are farther away from the coastline and in areas with lower incident solar radiation. When examining skua population trends, we discovered that the total number of breeding skuas in Admiralty Bay had increased by 293%, from 128 to 468 pairs, since 1978/1979. This dramatic increase was driven primarily by a tenfold increase in south polar skua pairs, as well as smaller increases in mixed and hybrid pairs. In contrast, there has been an overall decline (by 40%) in brown skua pairs during this same time, driven primarily by a large decrease in the breeding density of brown skua pairs in areas without penguin colonies.     

Larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), from southern Japan

Pelagic larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), are described and illustrated based on specimens collected off Tosa Bay, southern Japan. Postflexion larvae (8.2–11.9 mm BL) of Poecilopsetta plinthus are characteristic in having a series of melanophore patches along the dorsal and anal fin bases and the inner margins of the pterygiophore zones, and linear myoseptal pigmentation also along the inner margins of the latter. Preflexion and flexion larvae (5.0–6.3 mm BL) of Parabothus coarctatus are distinctive in having the dorsal fin origin located level with the dorsal margin of the eye and seven elongated rays in the anterior part of that fin. Received: November 18, 2000 / Revised: May 1, 2001 / Accepted: June 13, 2001     

Abundance and Biomass of Heterotrophic Flagellates, and Factors Controlling Their Abundance and Distribution in Sediments of Botany Bay

The abundance and biomass of heterotrophic flagellates were estimated monthly in sediments of Botany Bay during March 1999-February 2000. The annual abundance and biomass were in the ranges of 0.46-4.70 x 10(5) cells/cm(3) and of 0.30-8.61 micro g C/cm(3), respectively. The majority of heterotrophic flagellates (93-100%) were less than 10 mm in length and few flagellates were larger than 10 mm. Of the total microbial carbon biomass, heterotrophic flagellates made up about 5% (but at times up to 35%). The contribution of heterotrophic flagellates varied from month to month, and among the sites. The abundance of heterotrophic flagellates was negatively correlated with sediment grain size and positively correlated with the abundance of bacteria, algae (autotrophic flagellates and diatoms), and their probable grazers. A best subsets regression analysis showed that bacterial and algal abundance are the most important factors controlling the abundance of heterotrophic flagellates. When the previously reported grazing rates on bacteria were applied, heterotrophic flagellates would consume a maximum of 64% of bacterial standing stock daily in Botany Bay, suggesting that heterotrophic flagellates are important as bacterivores. However, the importance of heterotrophic flagellate grazing probably varies significantly among the sites and from month to month.     

Distribution,Abundance and population structure of the Antarctic krill (Euphausia superba Dana) in the Prydz Bay region,Antarctica

Summary This paper presents results of net sampling carried out on four marine science cruises, between 1981 and 1985, in the Prydz Bay region of Antarctica by the Australian Antarctic Division. Krill exhibited a patchy distribution and overall low abundance. The majority of sampling sites in January 1985 returned no post-larval krill or densities of <1 individual 1000 m^-3. The estimated mean abundance of E. superba in January 1985 was 6 individuals or 2 g (wet wt.) 1000 m^-3 integrated for the upper 200 m of the water column which represented 3.4% of the total zooplankton biomass. No more than five years-groups, including the larvae, were observed in Prydz Bay, with mean lengths of groups 1+, 2+, 3+ and 4+ being 24, 38, 46 and 53 mm (standard 1), respectively in the middle of January. A high proportion of naupliar stages observed in January 1985 indicated that spawning in Prydz Bay begins in January and examination of adult maturation showed that the spawning continues at least to March.     

Composition,Seasonal Dynamics,and Long-Term Fluctuations in the Density of Pelagic Polychaetes in Amurskii Bay,Sea of Japan

This is the first survey of the composition and seasonal density dynamics of the pelagic polychaete larvae in Amurskii Bay. This is a summary of the results of two years of observations (1996–1998). The larvae of 14 polychaete families have been recorded. The greatest number of species have been found in the family Spionidae. The most common were the larvae of Harmothoe imbricata (family Polynoidae) and Paraprionospio sp. (family Spionidae). The larvae of polychaetes have been found in plankton throughout the year and have two density peaks. The first peak was due to the spawning of H. imbricata; the second one was provided by representatives of several species of the family Spionidae, mostly Paraprionospio sp., Polydora ciliata, and P. caeca.     

Organic Matter,Carbon, Nitrogen and Phosphorus Contents of the Mesozooplankton,Mainly Acartia clausi,in a Tropical Brackish Lagoon (Ebrié Lagoon,Ivory Coast)

Mesozooplankton samples were collected over a period of one year in five stations of the Ebrié lagoon and analysed for organic, carbon, nitrogen and phosphorus contents. When zooplankton was dominated by A. clausi, body composition was relatively stable compared with the broad variability of environmental factors (mainly salinity, food abundance and composition), although a negative hypothetic influence of salinity may have occurred. Body composition was comparable when zooplankton was dominated by Pseudodiaptomus hessei and freshwater species, but contents were significantly lower for assemblages dominated by more exclusively marine species (Paracalanus spp., Oithona spp., marine cladocerans, chaetognates, etc.).     

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 patterns in the biomass of macrozoobenthic communities in Admiralty Bay (King George Island, South Shetlands, Antarctic)

The distribution patterns of macrozoobenthic communities as shown by the biomass of the higher taxa were investigated in Admiralty Bay. Material was collected at depths ranging from 4 to 500 m (102 quantitative samples), representing the full depth range of this basin and including areas characterized by the different levels of glacial influence. Five community groups were distinguished by multivariate analysis (clustering, MDS) based on the Bray--Curtis similarity index. In the Ezcurra Inlet, the area characterized by intensive glacial processes resulting in a high sedimentation rate, the distribution of biomass was not depth related, but was associated with the intensity of glacial disturbance along the axis of the fjord. The innermost part of this fjord, which receives strong outflows from glaciers, had a low biomass value (2.9 g/0.1 m²) and was dominated by polychaetes. The middle part of the fjord which is not so heavily disturbed had higher biomass values (46.1 g/0.1 m²) due to the dominance of bivalves. A clear depth gradient of biomass distribution was observed in bottom areas located far from glaciers, in the central basin of the bay, with three zones within the depth ranges 4–30, 40–380, and 400–500 m. The highest mean biomass values (92.5 g/0.1 m²) were found in the middle sublittoral (40–380 m) dominated by ascidians. In the shallow and deep assemblages, the biomass was lower (33.8 g/0.1 and 30.9 g/0.1 m² respectively), most probably associated with the ice disturbance in the shallows and lower food supply in the deepest part of the shelf.     

Taxonomic units, civilization, volcanism: Their influence on the chemical composition of ostracod carapaces (Kagoshima Bay, Kyushu Island, Japan)

To test the influence of both civilization and volcanism on the chemical composition of ostracod carapaces, 32 well-preserved valves from Kagoshima Bay (Kyushu Island, South Japan) were analysed by means of spark source mass spectrometry. In Kagoshima Bay, the extent of pollution corresponds to human activities. Kagoshima Bay is also an area of important volcanic activity: emissions from Sakurajima volcano are very frequent. The species analysed were Argilloecia hanaii, Callistocythere undulatifacialis, Pontocythere subjaponica and Loxoconcha tosaensis. Twenty-three chemical elements were detected. Among them, 11 were always above the limit of detection: Al, B, Cl, F, Fe, K, Na, P, S, Si and Zn. The correlation between Zn and Fe was characteristic of the volcanic environment. Two discriminant analyses were performed using either the location area or the species as grouping variables. An association between Zn and S is possible; it could be related to volcanic activity. The chemical composition of carapaces is ascribed to taxonomic units rather than the environment.     

Diel dynamics of net phytoplankton in Semyachik Lagoon (Kronotskii Bay, Kamchatka) in August 1982

At three stations in the shallow Semyachik Lagoon, Kronotskii Bay, Kamchatka, 72 species and intraspecific taxa of microalgae were found. Diatoms (55) were the dominant group. In the qualitative and quantitative respects, phytoplankton was mainly represented by casually planktonic (benthic) species of diatoms. The general features of diel dynamics of phytoplankton were similar at the three stations and depended on the fluctuations of the level of tidal currents. The highest biomass (up to 363 mg/m³) and density (up to 66000 cells/I) were observed between 12∶00 and 18∶00 at low tide; these characteristics were an order of magnitude lower than at high tide.     

Distribution, biomass and primary production of an Ahnfeltia tobuchiensis (Ahnfeltiales, Rhodophyta) population in the Bay of Izmena, Kunashir Island

Regularities of distribution and primary production of an Ahnfeltia tobuchiensis (Kanno et Matsubara) Mak. population, an agar-containing red alga, were studied in the Bay ot Izmena. Experiments were conducted in a flow-through system under conditions similar to algal habitats. The population of A. tobuchiensis unattached to the ground may be from a few centimeters to as much as 1 m thick. It has been shown that only the upper part of a stratum 15–20 cm thick receives a sufficient amount ot light to realize its production potential. While 15–20% of photosynthetically active radiation (PAR) of that falling on the water surface reaches the stratum surface, only 0.1% of PAR from that falling on the water surface penetrates through stratum 15 cm thick. It has been shown for A. tobuchiensis that its photosynthetic rate curve during the daytime mainly follows the PAR intensity curve. The highest values of photosynthetic rate have been measured in the afternoon when PAR reaches its maximum. It is noted that a stratum 15–20 cm thick has peak values ot net primary production (NPP) which averages 3.2 g C m^?2 day^?1. The total area of A. tobuchiensis population was 23.4 km², and its biomass was 125 000 tons in this area. On average, the NPP of the A. tobuchiensis population made up in summer and in autumn was 46.8 and 25.0% of its biomass, respectively.     

Seasonal Distribution of Phytoplankton in Yellowknife Bay,Great Slave Lake

The factors influencing the seasonal distribution of phytoplankton were determined between July 1975 and December 1977 in Yellowknife Bay, Great Slave Lake. The initiation of the spring bloom occurred during April of each year in response to changing light conditions and despite the 0 °C water temperatures. Although the plankton showed some fluctuations in density (100–400 mg/m³) during the summer, there was no vernal decrease in the size of the populations. The end of the growing season was characterized by a sharp drop in numbers near the end of October. Multiple regression analysis indicated that changes in the standing crop of the plankton during the summer were primarily related to temperature (r = 0.60) and the concentrations of NO₃–N (r=–0.74) and SiO₂ (r=–0.82). Changing light conditions probably had little effect on the population during the growing season. Chlamydomonas lapponica was dominant during April of each year. While the growth of this species caused a reduction in the concentrations of total phosphorus and NO₃–N, the level of SiO₂ remained constant and consequently diatoms (Asterionella formosa, Stephanodiscus astraea, Diatoma tenue var. elongatum and Melosira islandica) waxed rapidly during May. By the first of June, nutrient concentrations were low, thereby permitting the development of Dinobryon bavaricum and Dinobryon cylindricum. The extremely rapid decrease in the densities of common species during the fall was probably due to the rapid decline in temperature and light levels and the formation of ice on the bay.