Benthic fauna of Tsivolki Bay (Novaya Zemlya Archipelago,Kara Sea)

Benthic fauna in Tsivolki Bay (Novaya Zemlya Archipelago, Kara Sea) has been studied during the voyage of the R/V Professor Shtokman in 2013 and 2014. A peculiar feature of the bay is the presence of the Serp i Molot glacier in its inner part, which determines the extremely high content of suspended particles in the water column. The bay is divided into three parts: the inner part (close to the glacier), the middle basin, and the outer slope. These parts are separated from each other by several rises. Benthic communities changed gradually from the inner part of the bay towards the outer slope. Three communities were described from the data of nine grab stations (26 samples). The apex of the bay is occupied by the depleted community dominated by the isopod Saduria sabini and the bivalve Yoldiella lenticula, which can successfully survive the increased mineral sedimentation. In the middle basin, it is replaced by the transitional community with Ennucula tenuis and Portlandia arctica being the main dominants. Finally, the outer slope is inhabited by the community typical for the open parts of the Kara Sea. It is dominated by ^{Astarte crenata, Ophiacantha bidentata}, and Ophiopleura borealis. The main reason for macrobenthic distribution in the studied region is the content of mineral particles in the water column and bottom layers.     

Bottom Communities of Sedova Bay (Novaya Zemlya,the Kara Sea)

Oceanology - The benthic fauna of Sedova Bay (Kara Sea, Novaya Zemlya Archipelago) was studied during two cruises of the R/V Academik Mstislav Keldysh in 2015–2016. Three macrobenthic...     

Benthic Fauna of Oga Bay (Novaya Zemlya,Kara Sea)

Oceanology - The benthic fauna of Oga Bay (Kara Sea, Novaya Zemlya archipelago) was studied in 2015–2016 during the R/V Akademik Mstislav Keldysh expeditions. Five grab stations at depths of...     

Hydrochemical features of the Kara Sea aquatic area in summer 2015

During cruise 65 of the R/V Akademik Mstislav Keldysh in the Kara Sea, three transects were executed: one eastwards from the Novaya Zemlya Archipelago and two in the St. Anna and Voronin troughs. It was noted that the continental runoff affected the entire surveyed aquatic area, even at the northern extremity of the Novaya Zemlya Archipelago. The transect along the St. Anna Trough showed the presence of a slope frontal zone overlaid at the surface by a desalinated layer. The Voronin Trough was characterized by sliding of slope waters. The hydrochemical parameters show that the surveys were carried out during a recession of biological activity of the waters and that the peak bloom was over by that time. The hydrochemical structure of waters conformed to early autumn conditions, but before the beginning of intense cooling of surface waters.     

Macrobenthos of the Novaya Zemlya Trough

During the 54th cruise of the R/V Akademik Mstislav Keldysh the macrobenthos of the Novaya Zemlya Trough was studied using a Sigsby trawl along the submeridional transect near 75°30′N latitude at a depth range from 68 to 362 m. In total, 140 species of bottom animals were found. The relative role of the taxons was assessed using three indices: the number, biomass, and energy flow. Similarity indices were used for the comparison of the samples. The new material greatly contributes to the data on the composition of the fauna and the structure of the communities of the studied region. It was revealed that small scyphozoid polyps and sipunculoids play an important role in the trough’s community. The presence of the community dominated by Ophiocten sericeum (with the important role of small bivalves) was revealed for the first time not only at the eastern by also at the western slope of the Novaya Zemlya Trough. The sharpest changes in the composition and structure of the bottom community were confined to the zone of the transition from the trough floor to the slope. These changes are determined by the specificity of the macrorelief (of the floor and slope), the composition of the ground (soft brown silts abound in rhizopods and dense gray silts with an admixture of pebbles), and possibly by the hydrodynamic processes near the bottom.     

Fluorescence of dissolved organic matter as a marker for distribution of desalinated waters in the Kara Sea and bays of Novaya Zemlya archipelago

The optical properties and distribution of dissolved organic matter in the surface waters of the Kara Sea and bays of Novaya Zemlya archipelago were studied during the 63th cruise of the R/V Akademik Mstislav Keldysh. The fluorescence of dissolved organic matter has been studied over wide excitation (230–550 nm) and emission (240–650 nm) wavelength ranges. Based on the results of fluorescence measurements, we propose a simple technique for estimating the relative content of humic compounds entering the Kara Sea shelf region with Ob and Yenisei river runoff. We have found that the blue shift parameters of the DOM fluorescence are Δ_270–310 = 28 ± 2 nm and Δ_355–310 = 29 ± 2 nm. The highest contents of humic compounds in surface waters were measured on the transect across the desalinated layer of the Kara Sea, near the continental slope on the transect along the St. Anna Trough, and in the area of Sedova, Oga and Tsivol’ki bays. Traces of labile terrigenous organic matter were found in the region of the Voronin Trough, in the bays of the Severny Island of Novaya Zemlya, as well as in some freshwater reservoirs and ice samples of the archipelago. We established a conservative distribution of dissolved organic matter, whose content in water varied from 1.25 to 8.55 mg/L.     

Differences in the damage caused by hypoxia to the macrobenthic communities in source regions of hypoxic water and in regions with advected hypoxic water

The objective of this study was to determine the effects of transported hypoxic water on macrobenthic species composition in Isahaya Bay, Kyushu, Japan. To this end, we conducted a field survey of water quality, sediment quality, and the macrobenthic community across seasons. Hypoxic intensity, defined as the percentage of the time that a region exhibits hypoxic conditions [dissolved oxygen (DO) <?3.0 mg L^?1], was calculated for the summer period from July 1 to September 30, 2014 based on continuous monitoring data derived from six monitoring towers in the bay. Here, we discuss how the hypoxia-induced damage, defined as the change in the species compositions of the macrobenthic communities in the bay due to hypoxia, differs between the inner and middle regions of the bay (with muddy sediment) and the outer regions of the bay (with sandy sediment). A decrease in the density of macrobenthic species that was correlated to the period of lowest DO concentration (<?1.0 mg L^?1) was observed in the inner region of the bay. A large number of species disappeared from the macrobenthic community in the outer region after the DO concentration had dropped to its lowest level, even though this region presented the lowest hypoxic intensity (6.6%). The species that disappeared, including crustaceans and some polychaetes, were presumed to be sensitive to, and to have escaped from, hypoxia. Fewer species disappeared from the inner and intermediate regions of the bay, which had high hypoxic intensities of 14.0 and 26.7%, respectively, than from the outer region. The reason for this appeared to be a predominance of hypoxia-tolerant species in the inner and intermediate regions but not in the outer region. Our study suggests that estimating the effect of hypoxia in a spatially heterogeneous environment must be done with caution.     

Distribution,reproduction, and feeding of West African shrimp <Emphasis Type="Italic">Plesionika carinata</Emphasis> Holthuis, 1951 (Decapoda,Pandalidae)

Plesionika carinata is endemic in the West African tropical biogeographical realm and is distributed from the western Sahara coast (23°35′ N) to southern Namibia (29° S). A total of 263 individuals with a total carapace length of 31 to 71 mm have been studied. P. carinata juveniles are pelagic and occur over depths from 340 to 2000 m or more, mainly over the lower part of the continental slope in summer and over the upper part of the continental slope in autumn. Adults are mainly benthic and occur on the edge of the shelf and the upper part of the continental slope (at depths of 300 to 880 m). Ovigerous females have 750 to 3330 eggs 0.45–0.5 × 0.5–0.65 mm in size on pleopods. Plesionika carinata feeds on abundant micronectonic and macroplanktonic crustaceans (euphausiids and pelagic shrimps) at earlier pelagic stages; it is detritophagous/necrophagous and predatory near the bottom when adult.     

Circulation in the southwestern part of the Kara Sea in September 2007

During cruise 54 of the R/V Akademik Mstislav Keldysh to the southwestern Kara Sea (September 6 to October 7, 2007), a large amount of hydrophysical data with unique spatial resolution was obtained on the basis of measurements using different instruments. The analysis of the data gave us the possibility to study the dynamics and hydrological structure of the southwestern Kara Sea basin. The main elements of the general circulation are the following: the Yamal Current, the Eastern Novaya Zemlya Current, and the St. Anna Trough Current. All these currents are topographically controlled; they flow over the bottom slopes along the isobaths. The Yamal Current begins at the Kara Gates Strait and turns to the east as part of the cyclonic circulation. Then, it turns to the north and propagates along the Yamal coast over the 100-m isobath. The Eastern Novaya Zemlya Current (its core is located over the eastern slope of the Novaya Zemlya Trough) flows to the northeast. Near the northern edge of Novaya Zemlya, it encounters the St. Anna Trough Current, separates from the coast, and flows practically to the east merging with the continuation of the Yamal Current. A strong frontal zone is formed in the region where the two currents merge above the threshold that separates the St. Anna Trough from the Novaya Zemlya Trough and divides the warm and saline Arctic waters from the cooler and fresher waters of the southwestern part of the Kara Sea. This threshold, whose depth does not exceed 100–150 m, is a barrier that prevents the spreading of the Barents Sea and Arctic waters to the southwestern part of the Kara Sea basin through the St. Anna Trough.     

Contemporary condition of macrozoobenthos in ultrashallow zone of Taman Bay,Sea of Azov

The distribution of macrozoobenthic communities was studied in a vast ultrashallow (0–1.2 m deep) zone of northwestern Taman Bay (separated from the Kerch Strait by Chushka spit) in 2008–2009. Fifty-two species of benthic invertebrates were recorded. The species number, as well as Shannon and Pielou diversity indices, increased along Chushka spit from base to tip. The usual inhabitants of lagoons and estuaries of the Mediterranean Basin and the open Sea of Azov dominated in benthic communities: mollusks Abra segmentum and Hydrobia acuta and polychaetes Heteromastus filiformis and Hediste diversicolor (the latter only in summer). Changes in the community structure were largely determined by the seasonal dynamics of dominant species populations, which was similar to their dynamics in certainother transitional water bodies of the Mediterranean Basin. These changes indicate normal running of seasonal processes in the macrobenthic communities of Taman Bay in 2008 rather than the consequences of a catastrophic black oil spill in the Kerch Strait in November 2007.     

Macrofouling communities in the cooling system of the Vladivostok heat and power plant

The composition, structure, and distribution of flora and fauna on hydraulic facilities in the cooling system of the Vladivostok combined heat and power plant-2 were studied in summer and autumn of 2001. Cluster analysis was applied to differentiate Balanus rostratus, Mytilus trossulus, Jassa marmorata, Crassostrea gigas + Balanus rostratus, Modiolus modiolus + Pachycheles stevensii, Hydroides ezoensis, and Amphibalanus improvisus communities. The groups of fouling organisms found on the studied objects were shown to be assigned both to “physically controlled” and “biologically balanced” benthic communities. This study stresses the high similarity between the fouling communities of anthropogenic substrata and natural intertidal and subtidal benthic communities from adjacent areas of Peter the Great Bay.     

Features of hydrophysical and hydrochemical conditions in Blagopoluchiya Bay (Novaya Zemlya Archipelago)

The report presents the results of hydrophysical and hydrochemical studies in Blagopoluchiya Bay (Novaya Zemlya Archipelago) based on data of integrated expeditions of the Institute of Oceanology in the Kara Sea in 2007, 2013, and 2014. The main focus was the influence of the Ob and Yenisei rivers, as well as of the runoff of meltwaters from the coasts of the archipelago on the hydrochemical and hydrophysical structures of the bay waters. The features of water exchange between the bay and adjacent aquatic area are considered, along with the renewal mechanisms for deep waters in the bay (deeper than 100 m). The possible occurrence of stagnant effects in deep layers of the bay is evaluated.     

Characterization of Deep-sea Macrofauna in the Korean Exploration Claim Area in the Clarion-Clipperton Fracture Zone,Northeastern Pacific Ocean

Macrofauna in the Clarion-Clipperton Fracture Zone remain poorly understood, due both to gross undersampling and to the fact that most species collected from the area are new to science. Evaluation of the diversity and species distribution of the benthic fauna in this area is critical to predicting and managing the impacts of manganese nodule mining. In this study, we investigated the distribution of macrofauna to understand the natural variability in the macrobenthic community and, by extension, to establish a baseline for environmental risk assessment. Samples were collected from the KR5 block of the Korea Contract Area, within the abyssal area of the Clarion-Clipperton Fracture Zone in the northeastern Pacific Ocean, by the RV Onnuri from 2012–2014. A total of 36 core samples were examined in the survey, from which we identified 183 macrobenthic species in 25 faunal groups with a mean density of 257 ind/m2. Not taking into account meio-faunal groups such as nematodes and harpacticoid copepods, the highest percentage of individuals was represented by Arthropoda. The dominant species (> 1% of total density) were the tanaids Typhlotanais sp.1, and Akanthophoreus spp. and Stenotanais sp., the isopod Macrostylis sp.1, and the polychaetes Cirratulidae spp. and Levinsenia uncinata. The abundances of the two dominant species, the tanaid Typhlotanais sp1. and isopod Macrostylis sp.1., were positively correlated with total organic carbon (TOC). There were no differences in macrofaunal density and community structure between preserved areas (PRA), the potential benthic impacted site (BIS), and other areas near the BIS. In general, higher diversity was associated with homogeneous environmental conditions, with high nodule coverage (> 50%) and TOC.     

Methane gas Seeps Along the Oxic/Anoxic Gradient in the Black Sea: Manifestations, Biogenic Sediment Compounds and Preliminary Results on Benthic Ecology

Abstract. Sediment parameters (grain size, organic content, chloroplastic pigments, Adenylates, Potential hydrolytic activity and electron transport system activity) and benthic biota were studied in methane seep area south-west of the Crimean Peninsula in the Black Sea over a depth range from 60 to 260m. A control transect with similar depths was performed in an adjacent nonseep area. Methane seepage in this region occurs from 35 to ˜ 85m depth, passing the oxic anoxic interface zone at 130 to 180m. The methane seep areas were characterized by abundant carbonate precipitates which occurred in various shapes from small, flat structures to tall chimneys with increasing anoxia. The carbonates were associated with distinct bacterial mats. Most of the measured biochemical parameters in the sediment were quite similar in the seep and nonseep areas. The content of organic matter was higher and grain size was more uniform in the nonseep areas. However, the seep areas were charaterized by highter proportions of the larger fauna (size classes 0.5–1 mm and ≥ 1mm) as well as increased total numbers of benthic fauna in the suboxic and upper anoxic zone. The animals did not show any seep-specific adaptations. In addition to methane seepage, highly variable hydrochemical and sedimentary conditions on the lower shelf and upper slope may also play an important role in structuring the composition and distribution of the benthic fauna.     

Ichthyofauna of the Eastern Coast Bays of the Novaya Zemlya Archipelago

Based on 2014–2016 studies and published data on the ichthyofauna composition near the eastern coast of Novaya Zemlya, a revised list of fish fauna has been compiled. It includes 30 species from 23 genera and 13 families. The taxonomic diversity of ichthyofauna, its characteristics in respect to geographic range and biotopic groups of fish are considered. In general, ichthyological communities in bays off the eastern coast are similar in the species ratio to the communities in the open Kara Sea, and do not demonstrate any essential features of isolation.     

Response of infaunal macrobenthos to the sediment granulometry in a tropical continental margin–southwest coast of India

Surficial sediment samples, collected from the continental margin of the southwest coast of India in July 2004, were examined for the grain size and soft-bottom macrobenthic fauna, to understand the sediment granulometry and its effect on the faunal distribution. Samples were collected using Smith-McIntyre Grab, from 20 to 200 m depth range, consisting of mid-shelf, outer shelf and slope. Fine-grained sediment located in the mid shelf and supported low faunal abundance. Polychaetes constituted the bulk of the fauna. Feeding guild changed with depth and sediment granulometry. Coexistence of deposit feeders and carnivores in outer shelf and deposit feeders and filter feeders in the slope region indicated the effective utilization of different food resources. In general, richness and diversity were high in the southern region. Depth wise, the diversity and abundance were relatively high in the 50–75 m depth range. Correlation and BIO-ENV analysis showed that combination of different factors such as sediment texture, sediment sorting and depth were found to influence the distribution of macrobenthos. Hence, spatial variations observed in benthic community were presumably linked to the variations in sediment granulometry and the energy level conditions prevailing in the area.     

Seasonal variations in the community structures of macrobenthic fauna and their health status in an estuarine bay,Gwangyang Bay in Korea

Macrobenthic fauna in an estuarine Gwangyang Bay, southern Korean coast, were investigated to uncover recent variations in their community structures. In the study area, macrobenthic faunal communities were mainly composed of polychaete worms which were the most abundant faunal group with the highest values in species number and density, while mollusks accounted for the highest proportion in total biomass. There was no clear seasonal difference in species richness during the two year period of the investigation, but the mean density and biomass increased every spring and summer due to the mass recruitment of Theora fragilis. The Shannon’s diversity index (H') was more than 2.0 during most sampling seasons and did not show any significant seasonal difference except for the data in August, 2011 when azoic conditions occurred. The community structures of macrobenthos in Gwangyang Bay did not show any remarkable change in the dominance of the two top dominant species, Scoletoma longifolia and Heteromastus filiformis, which abundantly occurred in all seasons, except for the abundance peaks associated with high occurrence of T. fragilis and Paraprionospio cordifolia, especially in spring and summer and in autumn, respectively. These fauna changes reflected the changes in the macrobenthic community health status in Gwangyang Bay, where stable conditions and a healthy status prevailed in winter, but a slightly disturbed status prevailed from spring to autumn.     

Benthic Fauna of Stepovoi Bay (Novaya Zemlya Archipelago,Kara Sea)

Oceanology - Benthic fauna in Stepovoi Bay (Kara Sea, Novaya Zemlya) was studied during expeditions of the R/V Professor Shtokman in 2013–2014. Sampling was carried out at ten grab stations...     

白令海大型底栖动物群落结构及其空间分布格局

Due to its unique geological location, the Bering Sea is an ideal place to investigate the water exchange and ecosystem connectivity of the Pacific Ocean–Arctic Ocean and subarctic–Arctic region. Based on a number of summer surveys(July to September, 2010, 2012 and 2014), macrobenthic communities and their spatial-temporal patterns are exhibited for the majority of the Bering Sea(53°59′–64°36′N). The results show that the macrobenthic communities were dominated by northern cold-water species and immigrant eurythermic species, and the communities assumed a dispersed and patchy distribution pattern. Polychaetes(Scoloplos armiger), crustaceans(Ceradocus capensis) and sea urchins(Echinarachnius parma) were the main dominant groups in the shallow shelves; the sea star(Ctenodiscus crispatus) and the brittle star(Ophiura sarsii) were the main dominant groups in the continental slope; whereas small polychaetes(Prionospio malmgreni) dominated the basin area. Sediment type, water depth, and currents were the major factors affecting the structure and spatial distribution of the macrobenthic communities. Compared with other seas, the shallow areas of the Bering Sea showed an extremely high-standing biomass. In particular, the northern shelf area(north of St. Lawrence Islands and west of 170°W),which is primarily controlled by Anadyr Water, is an undersea oasis. In contrast, a deficiency in the downward transport of particulate organic carbon has resulted in a desert-like seabed in the basin area. By comparing our results to previous studies, we found that macrobenthic communities of the Bering Sea have undergone significant structural changes in recent decades, resulting in a decrease in abundance and an increase in biomass.In addition, populations of amphipods and bivalves in the northern shelves have decreased significantly and have been gradually replaced by other species. These changes might be associated with advanced seasonal ice melting,changes in organic carbon input, and global warming, indicating that large-scale ecosystem changes have been occurring in the Bering Sea.     

An assemblage of mollusks associated with the high latitude scleractinian coral <Emphasis Type="Italic">Alveopora japonica</Emphasis> (Eguchi 1968) in Jeju Island,off the south coast of Korea

Corals reefs and communities support a wide range of flora and fauna. The complete richness and abundance of faunal communities in either coral reefs or communities is not fully understood. This is especially true for high-latitude coral communities. In this work, we carried out an analysis of an Alveopora japonica associated mollusk assemblage, in Jeju Island, Korea. A. japonica is one of the major coral species present in high abundance (88–155 colonies m^-2), with a high recruitment rate (7.8 juvenile corals m^-2 yr^-1) in Jeju Island, and may serve as a habitat for other benthic organisms. In 2012, a total number of 579 A. japonica colonies with sizes ranging between 15.1-346.7 cm² in the surface area were collected from a 1m× 10m quadrat installed at a depth of 10 m at Keumneung, on the northwest coast of Jeju Island. Numerous benthic invertebrates were found to be associated with A. japonica colonies. Twenty-seven bivalves and gastropods were identified, including a boring mytilid, Lithophaga curta, and an arcid, Barbatia stearnsi. A zonalgeographical examination of the distribution ranges of these mollusks revealed a majority of warmer water species. Our observations also showed that A. japonica may be providing a habitat to grazing gastropod, Turbo cornutus, and encrusting Spondylidae and Chamidae bivalves. A. japonica forms a coral carpet with a distinct assemblage of bivalves. It is thought that the presence of these mollusks species in the coral indicates its use as a nursery for juvenile species, a ready food supply of organic detritus, and a refuge from predators.