Vadim Mokievsky

Benthic activity and biomass on the Yermak Plateau and in adjacent deep-sea regions northwest of Svalbard

Abstract Sediment samples collected during expedition ARK XIII/2 in summer 1997 with the German ice-breaker R/V POLARSTERN were investigated to estimate benthic microbial activity and total biomass of the smallest sediment-inhabiting organisms (size range from bacteria to meiofauna) from the Yermak Plateau northwest of Spitsbergen and adjacent deep-sea areas. Stations covered water depths from about 500xa0m north of Svalbard and on top of the Yermak Plateau to 3250–4250xa0m in the Fram Strait and the Nansen Basin. The area of investigations is located in a region with permanent ice-coverage, but in summer 1997 stations along the southern transect crossing the Yermak Plateau at about 81°N lay 50–100xa0km from the ice-edge. The hydrography of the area is characterized by the inflow of relatively warm, nutrient-rich and particle-laden Atlantic Water into the Arctic Ocean. The input of organic matter from primary production was estimated by measuring concentrations of sediment-bound chloroplastic pigments. Benthic activities and biomasses were evaluated by analyzing a series of biogenic compounds (i.e. bacterial exoenzymes, total adenylates, phospholipids, particulate proteins) in the sediments. Bacterial numbers and biomasses, meiofauna abundances, and nematode biomasses were determined for direct comparison with biochemical parameters. Faunal and biochemical data suggest a high current-driven lateral input of particulate organic matter from the South associated with increased sedimentation rates along the western slope of the Yermak Plateau.

The state of knowledge on deep-sea nematode taxonomy: how many valid species are known down there?

All available information from literature sources dealing with deep-sea nematode species was analyzed, in order to obtain an overview of the state of knowledge in deep-sea nematode taxonomy and answer the question of how many valid nematode species are known from the deep sea so far. One hundred and twenty-seven taxonomic and ecological literature sources reported a total of 638 valid species belonging to 175 genera and 44 families, from 474 deep-sea stations at depths of 400–8,380xa0m. This number is less than 16% of all known marine nematode species, whereas the deep sea comprises about 91% of the ocean bottom. Of these species, 71% were initially described from the deep sea. Most of the valid species have been reported from the North Atlantic, including the Mediterranean. The rest of the World Ocean, including the Pacific, Indian, Arctic and Antarctic oceans, is considerably less studied. The largest numbers of valid species were reported from the continental slope and the abyssal plains, while information on valid species from trenches, deep-sea canyons, and seamounts is extremely scanty. Some deep-sea families are much more investigated than others in proportion to their relative species abundances in the deep sea, i.e., the percentage of valid species from these families among all valid deep-sea species is much higher than the real percentage of species from these families reported in faunistic studies (e.g., Desmoscolecidae, Comesomatidae, Sphaerolaimidae, Benthimermithidae, Leptosomatidae, and Draconematidae). On the other hand, the families Xyalidae, Oxystominidae, and Monhysteridae were recognized as the most “underinvestigated,” as, in spite of their high species abundance in the deep sea, there are quite a few taxonomic studies on these taxa. Some deep-sea nematode species were reported from two or three oceans, and can be considered probable cosmopolitan species. Some number of probable eurybathic species were also found (the difference between minimum and maximum depth was from 1 km to more than 5xa0km).

Fauna associated with detached kelp in different types of subtidal habitats of the White Sea

The fauna, associated with Laminaria and other largebrown macroalgae was studied by using SCUBA anddredging in two different types of underwater habitatsof the White Sea.In shallow water fjords and bays, with a depth of nomore than 30–40 m, detached kelp (mainly Laminaria saccharina, L. digitata and Alaria esculenta) formed large accumulations. One ofthese benthic accumulations, which has existed morethan 20 years, was studied. It covers about2000 m2, and is about 2 m thick. The upper layerof the accumulation of fronds is characterized by highturbulence and is well aerated. The lower layer ischaracterized by anoxic conditions. Mats of sulphurbacteria were not observed, although fronds in themiddle layer were covered by layers of cyanobacteria.About 50 species of macroinvertebrates were found,mainly species that are normally associated withliving kelp, such as the detritivorous species Ophiura robusta and Gammarus oceanicus, and fewspecies that are specific inhabitants of organic-richbiotopes in the White Sea such as Capitellacapitata, Ophryotrocha irinae and Nebaliabipes. It was remarkable that in the shallow waterbasins of the White Sea, the process of decompositionof brown algae in the sublittoral takes place withoutsea urchins, and no other macrofaunal form plays anecological role in the mechanical breakdown of theplant substratum, even not in the large accumulationsof detached kelp.Along the open rocky shoreline, communities associatedwith dead detached kelp were situated at a depth of60–90 m, 40–50 m below the belt of living kelp. Inthis deep zone, no macroinvertebrates typical of thekelp community in the photic zone were found. Duringthe passage from the shoreline to the deeper benthiccommunity, where sea urchins were dominant, all plantdebris became fragmented. These deeper benthiccommunities appeared to be the zone for decompositionof the detached kelp.

Yermak Plateau revisited: spatial and temporal patterns of meiofaunal assemblages under permanent ice-coverage

Benthic sampling between 1997 and 2006 on the Yermak Plateau, a permanently ice-covered submarine peninsula northwest of Svalbard, exhibited regional differences with generally higher meiofauna numbers in southern and western parts (~2,250–2,300 ind. 10xa0cm−2 in the south-west, compared with ~1,200–1,350 ind. 10xa0cm−2 in the north-east). Distribution patterns suggest a current-driven lateral input of POM, produced in the high-productive Marginal Ice Zone, with increased intensity along the western slope of the plateau. Significant correlations between comparably ‘fresh’ sediment-bound phytodetritus and the taxonomic composition of meiofauna assemblages indicate that food quality decisively affects the community structure. The long-term development of meiobenthic communities showed no clear trend; however, a comparison of summer and winter data exhibited higher meiofauna densities and a more diverse composition in July samples. The predominance of small nematodes in the summer samples might point to reproductive activities stimulated by increased food availability. The taxonomic composition of nematode assemblages showed distinct regional differences, thereby indicating more stable environmental conditions in north-eastern parts of the Yermak Plateau.

Quantitative distribution of meiobenthos and the structure of the free-living nematode community of the mangrove intertidal zone in Nha Trang bay (Vietnam) in the South China Sea

Meiobenthic studies were performed in an intertidal area in the Be River estuary (Nha Trang Bay, Vietnam). The study area is an area of riverine-type mangroves that have been heavily damaged by human impacts, including timber cutting and waste. Three biotopes are situated in the middle intertidal zone: a fringe of Rhizophora stylosa, a bush area composed of Avicennia aff. alba behind it, and muddy sand with fiddler crabs (Uca spp.), which is free of mangrove plants. Three replicate samples of meiobenthos were collected in each biotope and each sample was subdivided into two layers: 0–1 and 1–4 cm. The abundance of metazoan meiobenthos varied from 735 specimens/10 cm2 in the Uca spp. biotope to 244 specimens/10 cm2 beneath the Rhizophora trees. Six taxonomic groups of high rank were found among the meiofauna: Nematoda, Copepoda (Harpacticoida), Oligochaeta, Turbellaria, Kinorhyncha, and Foraminifera (Allogromiida). The spatial variability of meiobenthos and its key taxa was estimated and the spatial distribution patterns of free-living nematode species were described. About 90% of the total meiobenthos inhabited the upper 0–1 cm of the sediments. Nematodes constituted 90–95% of all meiobenthic organisms in the samples. A total of 48 species of free-living nematodes were found in the investigated mangrove intertidal area. In terms of species composition and set of dominants, the nematode community is comprised of three local assemblages: one of them inhabits the uppermost centimeter in the Uca and Avicennia biocenoses; the second assemblage occupies the upper sediment layer in the Rhizophora stand; a less abundant but specific assemblage of several nematode species occurs in the subsurface sediments at all three sites.

Russia's protected areas: a survey and identification of development problems

Natural habitat preservation, i.e. the creation and management of Protected Natural Areas (PNAs), is one of the most important forms of biodiversity conservation. The most widespread types of PNAs in Russia are Zakazniks (State Nature Refuges) and Natural Monuments, but unlike Zapovedniks (State Nature Reserves) these types of Russian PNAs are little-known to foreign ecologists. Thus the main attention of this article is given to the problems of Zakazniks and Natural Monuments while other types of Russian PNAs are mentioned briefly. In many regions of Russia, Zakazniks and Natural Monuments are considered to be the core components for the regional protection of biodiversity. Non-Governmental Organizations play an important role in the creation and management of PNAs. The recent sudden change of circumstances in Russia have given rise to many problems which threaten the existence of Zakazniks and Natural Monuments. Possible means of saving these PNAs include: (i) promoting the interest of local people in protecting biodiversity; and (ii) supporting local authorities, and public initiatives and regional programmes in the creation of local PNA networks.

Marine protected areas: Theoretical background for design and operation

This review paper deals with the problem of the design and operation of marine reserves in the context of modern views on the hierarchical organization of marine ecosystems. The state of the art in the theoretical aspect of the establishment and development of marine protected areas (MPAs) is discussed. Despite the increasing number of publications on MPAs, which are mainly focused on social and economic issues, studies devoted to the ecological bases for the establishment and operation of marine reserves are still scarce. However, the low efficiency of the existing MPAs and their systems may be a result of the lack of an ecological background in MPA designs. Recent threats to the diversity of marine organisms are analyzed, and changes in the relative significance of anthropogenic factors affecting the marine biological diversity are assessed. The hierarchical nature of and the existence of characteristic spatial scales in the marine ecosystems are critical issues that must be taken into account together with scale-oriented analysis of the anthropogenic threats. On the basis of the scale-oriented concept of the marine ecosystems, new theoretical approaches to the design and operation of MPAs are formulated. In particular, theoretical bases for the estimation of the minimal size of marine reserves and a hierarchical approach to the design of MPA systems are proposed. Formal schemes of classification of sea bottom communities (The Marine Habitat Classification for Britain and Ireland and EUNIS) are discussed.

Metazoan meiobenthos and nematode assemblages in the Nyegga Region of methane seepage (Norwegian Sea)

Based on visual observations in the Nyegga (Norwegian Sea) methane seep area we defined arbitrary boundaries and defined the following types of microbiotopes: the siboglinid field, bacterial mat, and background sediment. The metazoan meiobenthos consisted of 14 major taxa; the Nematoda dominated at seven of the eight stations. The taxonomic diversity of metazoan meiobenthos in the siboglinid fields was higher than that in the background bottom area. The average population density in siboglinid microbiotope exceeded the abundance of organisms in the background sediments by 1.3 times. The nematode population and total meiobenthos varied in bacterial maths. The modal size fraction of meiobenthos and nematodes regardless of microbiotopes fell on samples that were obtained on sieves with 63–125 μm mesh sizes. In total, 88 nematod species belonging to 26 families and 63 genera were recorded. The species diversity decreased in the direction from the background biotope to siboglinid fields and further to bacterial mats.

High-resolution habitat mapping on mud fields: New approach to quantitative mapping of Ocean quahog

During 2009-2012 stocks of the bivalve Arctica islandica (Linnaeus, 1767) (Ocean quahog) in Kandalaksha Bay (the White Sea) has been assessed using a side-scan sonar, grab sampling and underwater photo imaging. Structurally uniform localities were highlighted on the basis of side-scan signal. Each type of a signal reflects combination of sediment type, microtopography and structural characteristics of benthic community. The distribution of A. islandica was the predominant factor in determining community structure. Seabed attributes considered most significant were defined for each type of substrate type. Relations of sonar signal and sediment type were used for landscape mapping based on sonar data. Community characteristics at known localities were reliably interpolated to the area of survey using statistical processing of geophysical data. A method of integrated sonar and sampling data interpretation for high-resolution mapping of A. islandica by biomass groups, benthic faunal groups and associated habitats was developed.

Nematode assemblages from the Kandalaksha Depression (White Sea, 251–288 m water depth)

AbstractnThe shallow-water nematodes of the White Sea are relatively well studied; however, information on the nematode fauna inhabiting the deepest part of this sea is very scarce. The composition of the nematode assemblages (at species and genus level) was studied in samples collected during four sampling occasions in the deepest part of the Kandalaksha Depression (the White Sea) in July 1998, October 1998, May 1999, and November 1999. Samples were collected from a depth of 251–288xa0m with the aid of a multicorer. In total, 59 nematode morphotypes belonging to 37 genera and 18 families were distinguished. The genera Sabatieria and Filipjeva dominated at all stations, followed by Aponema, Desmoscolex, and Quadricoma. The composition of the dominant genera can be considered typical for this depth range in temperate and Arctic waters, although Filipjeva and Aponema were among the dominant genera for the first time. The most abundant species were Sabatieria ornata, Aponema bathyalis, and Filipjeva filipjevi. In general, diversity of the nematode assemblages was lower than in the temperate and Arctic continental shelf and slope with reduced evenness and species richness. The evenness of nematode assemblages and other diversity indices decreased with increasing sediment depth. Based on the valid species and genera recorded, the nematode fauna of the Kandalaksha Depression showed a higher resemblance to that found in the shallow waters of Kandalaksha Bay.