Sulfur and carbon in mIcrobial processes in waters and sediments of the Kara Sea in September 2007

Results of microbiological, biogeochemical and isotope geochemical studies in the Kara Sea are described. Samples for these studies were obtained during Cruise 54 of R/V Akademik Mstislav Keldysh in September 2007. The studied area covered the northern, central, and southwestern parts of the Kara Sea and the Obskaya Guba (Ob River estuary). Quantitative characteristics of total bacterial population and activity of microbial processes in the water column and bottom sediments were obtained. Total abundance of bacterioplankton (BP) varied from 250000 cells/ml in the northern Kara Sea to 3000000 cells/ml in the Obskaya Guba. BP abundance depended on concentration of suspensded matter. Net BP production was minimal in the central Kara Sea (up to 0.15-0.2 µg C/l/day) and maximal (0.5-0.75 µg C/l/day) in the Obskaya Guba. Organic material at the majority of stations at the Ob transect predominantly contained light carbon isotopes (-28.0 to -30.18 per mil) of terrigenous origin. Methane concentration in the surface water layer varied from 0.18 to 2.0 µl CH4/l, and methane oxidation rate varied from 0.1 to 100 nl CH4/l/day. Methane concentration in the upper sediment layer varied from 30 to 300 µl CH4/dm**3; rate of methane formation was varied from 44 to 500 nl CH4/dm**3/day and rate of methane oxidation - from 30 to 2000 nl CH4/dm**3/day. Rate of sulfate reduction varied from 4 to 184 µg S/dm**3/day.

Literature review of elasmobranch bycatch and retention rate

To address growing concern over the effects of fisheries non-target catch on elasmobranchs worldwide, the accurate reporting of elasmobranch catch is essential. This requires data on a combination of measures, including reported landings, retained and discarded non-target catch, and post-discard survival. Identification of the factors influencing discard vs. retention is needed to improve catch estimates and to determine wasteful fishing practices. To do this we compared retention rates of elasmobranch non-target catch in a broad subset of fisheries throughout the world by taxon, fishing country, and gear. A regression tree and random forest analysis indicated that taxon was the most important determinant of retention in this dataset, but all three factors together explained 59% of the variance. Estimates of total elasmobranch removals were calculated by dividing the FAO global elasmobranch landings by average retention rates and suggest that total elasmobranch removals may exceed FAO reported landings by as much as 400%. This analysis is the first effort to directly characterize global drivers of discards for elasmobranch non-target catch. Our results highlight the importance of accurate quantification of retention and discard rates to improve assessments of the potential impacts of fisheries on these species.

Sea-surface temperature reconstruction of sediments from the North Pacific and North Atlantic

Holocene climate variability is investigated in the North Pacific and North Atlantic realms, using alkenone-derived sea-surface temperature (SST) records as well as a millennial scale simulation with a coupled atmosphere-ocean general circulation model (AOGCM). The alkenone SST data indicate a temperature increase over almost the entire North Pacific from 7 cal kyr BP to the present. A dipole pattern with a continuous cooling in the northeastern Atlantic and a warming in the eastern Mediterranean Sea and the northern Red Sea is detected in the North Atlantic realm. Similarly, SST variations are opposite in sign between the northeastern Pacific and the northeastern Atlantic. A 2300 year long AOGCM climate simulation reveals a similar SST seesaw between the northeastern Pacific and the northeastern Atlantic on centennial time scales. Our analysis of the alkenone SST data and the model results suggests fundamental inter-oceanic teleconnections during the Holocene.

The Global Plankton Database: an inventory and data from the Former Soviet Union expeditions

At present time, there is a lack of knowledge on the interannual climate-related variability of zooplankton communities of the tropical Atlantic, central Mediterranean Sea, Caspian Sea, and Aral Sea, due to the absence of appropriate databases. In the mid latitudes, the North Atlantic Oscillation (NAO) is the dominant mode of atmospheric fluctuations over eastern North America, the northern Atlantic Ocean and Europe. Therefore, one of the issues that need to be addressed through data synthesis is the evaluation of interannual patterns in species abundance and species diversity over these regions in regard to the NAO. The database has been used to investigate the ecological role of the NAO in interannual variations of mesozooplankton abundance and biomass along the zonal array of the NAO influence. Basic approach to the proposed research involved: (1) development of co-operation between experts and data holders in Ukraine, Russia, Kazakhstan, Azerbaijan, UK, and USA to rescue and compile the oceanographic data sets and release them on CD-ROM, (2) organization and compilation of a database based on FSU cruises to the above regions, (3) analysis of the basin-scale interannual variability of the zooplankton species abundance, biomass, and species diversity.

Tab. 1: Chupa Inlet, Kandalaksha Bay of the White Sea. Population density of the dominant boreal copepod species and daily pellet carbon flux

Data on the zooplankton community structure, gut evacuation rate and carbon content of zooplankton faecal pellets were used for assessing the contribution of zooplankton to vertical carbon fluxes in the White and Kara Seas. The results revealed strong regional and seasonal variations of pellet carbon input related to differences in structure and dynamics of the zooplankton communities in the regions studied. In the deep regions of the White Sea, maximum daily pellet carbon flux from the 0-50 m layer was observed in the spring. It reached 98 mg Corg m-2 day-1 and coincided with a strong predominance of the large arctic herbivorous copepod Calanus glacialis in the surface layers. In summer and fall, it decreased by 1 to 2 orders of magnitude due to migration of this copepod to its overwintering depths. In contrast, in the shallow coastal regions, the pellet production was low in spring, gradually increased during summer and reached its maximum of 138 mg Corg m-2 day-1 by late summer to beginning of autumn. Such a seasonal pattern was in accordance with the seasonal variation of abundance of major pellet producers, the small boreal copepods Acartia bifilosa, Centropages hamatus, and Temora longicornis. In the estuarine zone of the Kara Sea, the pellet flux was mostly formed by pellets of brackish-water omnivorous copepods. It varied from 35 mg Corg m-2 day-1 in 1997 to 96 mg Corg m-2 day-1 in 1999. In the central Kara Sea with its typical marine community, the daily flux reached 125 mg Corg m-2 day-1 in summer. The results of our calculations indicate that both in the White and Kara seas zooplankton pellet carbon contributes up to 30 % to the total carbon flux during particular seasons.

Vertical distribution of large particulate matter in the Western Mediterranean Sea

The relationship between mesoscale hydrodynamics and the distribution of large particulate matter (LPM, particles larger than 200 ?m) in the first 1000 m of the Western Mediterranean basin was studied with a microprocessor-driven CTD-video package, the Underwater Video Profiler (UVP). Observations made during the last decade showed that, in late spring and summer, LPM concentration was high in the coastal part of the Western Mediterranean basin at the shelf break and near the continental slope (computed maximum: 149 ?g C/l between 0 and 100 m near the Spanish coast of the Gibraltar Strait). LPM concentration decreased further offshore into the central Mediterranean Sea where, below 100 m, it remained uniformly low, ranging from 2 to 4 ?g C/l. However, a strong variability was observed in the different mesoscale structures such as the Almeria-Oran jet in the Alboran Sea or the Algerian eddies. LPM concentration was up to one order of magnitude higher in fronts and eddies than in the adjacent oligotrophic Mediterranean waters (i.e. 35 vs. 8 ?g C/l in the Alboran Sea or 16 vs. 3 ?g C/l in a small shear cyclonic eddy). Our observations suggest that LPM spatial heterogeneity generated by the upper layer mesoscale hydrodynamics extends into deeper layers. Consequently, the superficial mesoscale dynamics may significantly contribute to the biogeochemical cycling between the upper and meso-pelagic layers.

Reconstructed ice-sheet limit in the Kara and Barents Sea area at about 50,000 years ago (Markhida Line)

Glacial landforms in northern Russia, from the Timan Ridge in the west to the east of the Urals, have been mapped by aerial photographs and satellite images supported by field observations. An east-west trending belt of fresh hummock-and-lake glaciokarst landscapes has been traced to the north of 67°N. The southern boundary of these landscapes is called the Markhida Line, which is interpreted as a nearly synchronous limit of the last ice sheet that affected this region. The hummocky landscapes are subdivided into three types according to the stage of postglacial modification: Markhida, Harbei and Halmer. The Halmer landscape on the Uralian piedmont in the east is the freshest, whereas the westernmost Markhida landscape is more eroded. The west- east gradient in morphology is considered to be a result of the time-transgressive melting of stagnant glacier ice and of the underlying permafrost. The pattern of ice-pushed ridges and other directional features reflects a dominant ice flow direction from the Kara Sea shelf. Traces of ice movement from the central Barents Sea are only discernible in the Pechora River left bank area west of 50°E. In the Polar Urals the horseshoe-shaped end moraines at altitudes of up to 560 m a.s.l. reflect ice movement up-valley from the Kara Ice Sheet, indicating the absence of a contemporaneous ice dome in the mountains. The Markhida moraines, superimposed onto the Eemian strata, represent the maximum ice sheet extent in the western part of the Pechora Basin during the Weichselian. The Markhida Line truncates the huge arcs of the Laya-Adzva and Rogovaya ice-pushed ridges protruding to the south. The latter moraines therefore reflect an older ice advance, probably also of Weichselian age. Still farther south, fluvially dissected morainic plateaus without lakes are of pre-Eemian age, because they plunge northwards under marine Eemian sediments. Shorelines of the large ice-dammed Lake Komi, identified between 90 and 110 m a.s.l. in the areas south of the Markhida Line, are radiocarbon dated to be older than 45 ka. The shorelines, incised into the Laya-Adzva moraines, morphologically interfinger with the Markhida moraines, indicating that the last ice advance onto the Russian mainland reached the Markhida Line during the Middle or Early Weichselian, before 45 ka ago.

Grain shape of sediment from the Weddell Sea

Very fine quartz sand was examined from Paleogene and Neogene sediments of ODP Sites 693, 694, 695, 696, and 697 to determine their grain roundness using Fourier analysis and SEM surface texture characteristics. The objective of this study was to identify grain roundness and surface texture characteristics unique to East (Site 693) and West (Sites 695, 696, and 697) Antarctica and to glacial regimes. Once identified, these distinguishing features could then be used to determine changes in source area and glacial conditions in the central Weddell Sea Basin (Site 694). Three end members of very fine quartz sand are recognized in the Oligocene to Pleistocene sediments of the Weddell Sea: angular, rounded, and intermediate. End member 1 (angular) consists of extremely angular grains with numerous fracture textures. Previous investigations suggested that these sands are derived from crystalline rocks that fractured during formation or deformation and/or were exposed to weathering by ice. In this study, however, the correlation of angularity with ice activity is problematical as the most angular sands were recovered in the lower Oligocene sediments of the South Orkney Microcontinent, a period of temperate climatic conditions. End member 3 (rounded) consists of rounded grains with chemically and mechanically produced surface textures. These sands are presumed to be derived from the Beacon-type rocks in East Antarctica and the sedimentary deposits of the Northern Antarctic Peninsula. End member 2 (intermediate) grains display crystalline nodes and grain embayments. They are thought to be derived from felsic intrusives, East Antarctic quartzites, basement metamorphics of the South Orkney Microcontinent, and/or the Andean intrusive series of West Antarctica. Unfortunately, no features unique to either the East or West Antarctic sediment sources or to glacial conditions could be isolated. Therefore, the objective of determining provenance changes and sediment erosion and transport mechanisms could not be achieved using this approach.

Microbial community, biomarker concentrations and their isotopic signature in sediment of Gullfaks and Tommeliten methane seeps in the Northern North Sea

Gullfaks is one of the four major Norwegian oil and gas fields, located in the northeastern edge of the North Sea Plateau. Tommeliten lies in the greater Ekofisk area in the central North Sea. During the cruises HE 208 and AL 267 several seep locations of the North Sea were visited. At the Heincke seep at Gullfaks, sediments were sampled in May 2004 (HE 208) using a video-guided multiple corer system (MUC; Octopus, Kiel). The samples were recovered from an area densely covered with bacterial mats where gas ebullition was observed. The coarse sands limited MUC penetration depth to maximal 30 centimeters and the highly permeable sands did not allow for a high-resolution, vertical subsampling because of pore water loss. The gas flare mapping and videographic observation at Tommeliten indicated an area of gas emission with a few small patches of bacterial mats with diameters <50 cm from most of which a single stream of gas bubbles emerged. The patches were spaced apart by 10-100 m. Sampling of sediments covered by bacterial mats was only possible with 3 small push cores (3.8 cm diameter) mounted to ROV Cherokee. These cores were sampled in 3 cm intervals. Lipid biomarker extraction from 10 -17 g wet sediment was carried out as described in detail elsewhere (Elvert et al., 2003; doi:10.1080/01490450303894). Briefly, defined concentrations of cholestane, nonadecanol and nonadecanolic acid with known delta 13C-values were added to the sediments prior to extraction as internal standards for the hydrocarbon, alcohol and fatty acid fraction, respectively. Total lipid extracts were obtained from the sediment by ultrasonification with organic solvents of decreasing polarity. Esterified fatty acids (FAs) were cleaved from the glycerol head group by saponification with methanolic KOH solution. From this mixture, the neutral fraction was extracted with hexane. After subsequent acidification, FAs were extracted with hexane. For analysis, FAs were methylated using BF3 in methanol yielding fatty acid methyl esters (FAMES). The fixation for total cell counts and CARD-FISH were performed on-board directly after sampling. For both methods, sediments were fixed in formaldehyde solution. After two hours, aliquots for CARD-FISH staining were washed with 1* PBS (10mmol/l sodium phosphate solution, 130mmol/l NaCl, adjusted to a pH of 7.2) and finally stored in a 1:1 PBS:ethanol solution at -20°C until further processing. Samples for total cell counts were stored in formalin at 4°C until analysis. For sandy samples, the total cell count/CARD-FISH protocol was optimized to separate sand particles from the cells. Cells were dislodged from sediment grains and brought into solution with the supernatant by sonicating each sample onice for 2 minutes at 50W. This procedure was repeated four times and supernatants were combined. The sediment samples were brought to a final dilution of 1:2000 to 1:4000 and filtered onto 0.2µm GTTP filters (Millipore, Eschbonn, Germany).