Faecal pellet production of copepoda collected in water depth up to 30 meters in the eastern Mediterranean Sea in Oktober 2008 during SES_GR2

Mesozooplankton is collected by vertical tows within the Black sea water body mass layer in the NE Aegean, using a WP-2 200 µm net equipped with a large non-filtering cod-end (10 l). Macrozooplankton organisms are removed using a 2000 µm net. A few unsorted animals (approximately 100) are placed inside several glass beaker of 250 ml filled with GF/F or 0.2 µm Nucleopore filtered seawater and with a 100 µm net placed 1 cm above the beaker bottom. Beakers are then placed in an incubator at natural light and maintaining the in situ temperature. After 1 hour pellets are separated from animals and placed in separated flasks and preserved with formalin. Pellets are counted and measured using an inverted microscope. Animals are scanned and counted using an image analysis system. Carbon- Specific faecal pellet production is calculated from a) faecal pellet production, b) individual carbon: Animals are scanned and their body area is measured using an image analysis system. Body volume is then calculated as an ellipsoid using the major and minor axis of an ellipse of same area as the body. Individual carbon is calculated from a carbon- total body volume of organisms (relationship obtained for the Mediterranean Sea by Alcaraz et al. (2003) divided by the total number of individuals scanned and c) faecal pellet carbon: Faecal pellet length and width is measured using an inverted microscope. Faecal pellet volume is calculated from length and width assuming cylindrical shape. Conversion of faecal pellet volume to carbon is done using values obtained in the Mediterranean from: a) faecal pellet density 1,29 g cm**3 (or pg µm**3) from Komar et al. (1981); b) faecal pellet DW/WW=0,23 from Elder and Fowler (1977) and c) faecal pellet C%DW=25,5 Marty et al. (1994).

Iron and manganese in bottom sediments and interstitial waters sampled in the White Sea on August 21-30, 2003

Iron and manganese in bottom sediments studied along the sublatitudinal transect from Kandalaksha to Arkhangelsk are characterized by various contents and speciations depending on sedimentation environment, grain size of sediments, and diagenetic processes. The latter include redistribution of reactive forms leading to enrichment in Fe and Mn of surface sediments, formation of films, incrustations, and ferromanganese nodules. Variations in total Fe content (2-8%) are accompanied by changes in concentration of its reactive forms (acid extraction) and concentration of dissolved Fe in interstitial waters (1-14 µM). Variations in Mn content in bottom sediments (0.03-3.7%) and interstitial waters (up to 500 µM) correspond to high diagenetic mobility of this element. Changes in oxidation degree of chemical elements result in redox stratification of sediment strata with maximum concentrations of Fe, Mn, and sulfides. Organic matter of bottom sediments with considerable terrestrial constituent is oxidized by bottom water oxygen mainly at the sediment surface or in anaerobic conditions within the sediment strata. The role of inorganic components in organic matter oxidation changes from surface layer bottom sediments (where manganese oxyhydroxide dominates among oxidants) to deeper layers (where sulfate of interstitial water serves as the main oxidant). Differences in river runoff and hydrodynamics are responsible for geochemical asymmetry of the transect. The deep Kandalaksha Bay serves as a sediment trap for manganese (Mn content in sediments varies within 0.5-0.7%), whereas the sedimentary environment in the Dvina Bay promotes its removal from bottom sediments (Mn 0.05%).

Abundance and biomass of benthic foraminifera in bottom sediments from the Sea of Okhotsk and the Pacific Ocean

A study of distribution of live individuals of benthic foraminifera in sediments of the Sea of Okhotsk and of the Northwestern Basin of the Pacific Ocean shows that they can be present in sediments up to depth of 30 cm and probably can live there for long periods, sometimes forming high concentrations. Living individuals in the subsurface layer often account for more than 50% of total biomass, which varies from 1 to 21 g/m**2 in different morphological structures. The largest biomass values are attained in underwater rises embedded in relatively warm, oxygen-saturated Pacific waters. Minimum total biomass concentrations occur in deep-water depressions where stagnation phenomena are observed. Foraminifera biomass everywhere decreases gradually with increasing depth from the surface of sediments regardless of relief, depth, and nature of sediments.

Profiles of diatoms, pollen, XRD, XRF and organic composition of two sediment cores (PG2022 and PG2023) from Lake Kyutyunda in Yakutia, NE Siberia, Russia

Although the climate development over the Holocene in the Northern Hemisphere is well known, palaeolimnological climate reconstructions reveal spatiotemporal variability in northern Eurasia. Here we present a multi-proxy study from north-eastern Siberia combining sediment geochemistry, and diatom and pollen data from lake-sediment cores covering the last 38,000 cal. years. Our results show major changes in pyrite content and fragilarioid diatom species distributions, indicating prolonged seasonal lake-ice cover between ~13,500 and ~8,900 cal. years BP and possibly during the 8,200 cal. years BP cold event. A pollen-based climate reconstruction generated a mean July temperature of 17.8°C during the Holocene Thermal Maximum (HTM) between ~8,900 and ~4,500 cal. years BP. Naviculoid diatoms appear in the late Holocene indicating a shortening of the seasonal ice cover that continues today. Our results reveal a strong correlation between the applied terrestrial and aquatic indicators and natural seasonal climate dynamics in the Holocene. Planktonic diatoms show a strong response to changes in the lake ecosystem due to recent climate warming in the Anthropocene. We assess other palaeolimnological studies to infer the spatiotemporal pattern of the HTM and affirm that the timing of its onset, a difference of up to 3,000 years from north to south, can be well explained by climatic teleconnections. The westerlies brought cold air to this part of Siberia until the Laurentide ice-sheet vanished 7,000 years ago. The apparent delayed ending of the HTM in the central Siberian record can be ascribed to the exceedance of ecological thresholds trailing behind increases in winter temperatures and decreases in contrast in insolation between seasons during the mid to late Holocene as well as lacking differentiation between summer and winter trends in paleolimnological reconstructions.

Chemical composition of bottom sediments from the northern part of the Deryugin Trough, Sea of Okhotsk

Distribution trace element contents in the upper (up to 5 m) Holocene-Upper Pleistocene sediment layer along the northern and southern sublatitudinal profiles in the northern part of the Deryugin Trough is discussed. Mathematical processing of chemical analysis data has been made. On the basis of the cluster analysis 16 elements have been combined into 5 geochemical groups. Two of them (1 - Ag-Mo group and 2 - Mn-Ba-Ni-Sr group) were considered in detail. Analysis of Ag and Mo distributions in the sediments and findings of molybdenite permitted to conclude that enrichment of the sediments by these elements resulted from edaphic washing of magmatic rocks containing Ag-Mo mineralization and probably located on the northwestern slope of the Deryugin trough. The second geochemical group is most likely connected with hydrothermal barite mineralization found in the northeastern part of the Deryugin trough. Considering Mn distribution in bottom sediment cores supply of Mn was pulsating. This allows concluding that during Holocene - Late Pleistocene three cycles of hydrothermal activity occurred in the Deryugin Trough, and the most intensive one was in Holocene.

Manganese contents and accumulation rates in reduced bottom sediments of the Sea of Okhotsk

Manganese contents in reduced sediments and accumulation rates were investigated. Their values in sediments of most of cores are background (0.03-0.07 %).Anomalous concentrations (up to 2.5 %) and accumulation rates (up to 60 mg/cm**2/ka) occur near the known region of hydrothermal barite mineralization in the Derugin Basin. High accumulation rates of Mn (>10 mg/cm**2/ka) also occur in Holocene sediments to south-east from the Derugin Basin. It can be assumed that high Mn contents and accumulation rates occur there due to transportation of Mn-rich water from the Derugin Basin in the near-bottom layer under the lower border of the Sea of Okhotsk Intermediate Water. Intensive Mn accumulation is also typical for the South Okhotsk Basin near the Bussol Strait. Mn accumulation rates of glacial sediments of the second oxygen isotope stage are less significant, which is presumed to be caused by paleoceanological reasons.

Geochemical and biogeochemical parameters of bottom sediments from the area of the Spitsbergen (Svalbard) Archipelago

Quantitative characteristics for rates of diagenetic processes in the upper (0-30 cm) layer of sedimentary deposits in the area of the Spitsbergen (Svalbard) Archipelago (78°-80°N) were obtained by lithologo-geochemical, radioisotope (35S, 14C), and stable isotope (d34S, d13C) studies. It was proved that rates of diagenetic processes in polar deposits at 123-395 m depth affected by the East Spitsbergen ''warm'' current are mostly determined by bioproductivity and are commensurate with rates of processes in shelf deposits of temperate latitudes. High contents of migratory methane (up to 263 ml/dm**3) and isotopically-light organic carbon (Corg, d13C = -30 per mil PDB) were found in the 1 m layer of shelf deposits (at 123 m sea depth) with low bacterial in situ production of methane. It was shown that methane is not utilized in the deposits by the methanotrophic bacterial community and it may be supplied to the water mass and, probably, to the atmosphere.

Chemical composition of bottom sediments at DSDP Sites 91-595 and 91-596 and ODP Sites 114-701 and 129-801

Subducted sediments play an important role in arc magmatism and crust-mantle recycling. Models of continental growth, continental composition, convergent margin magmatism and mantle heterogeneity all require a better understanding of the mass and chemical fluxes associated with subducting sediments. We have evaluated subducting sediments on a global basis in order to better define their chemical systematics and to determine both regional and global average compositions. We then use these compositions to assess the importance of sediments to arc volcanism and crust-mantle recycling, and to re-evaluate the chemical composition of the continental crust. The large variations in the chemical composition of marine sediments are for the most part linked to the main lithological constituents. The alkali elements (K, Rb and Cs) and high field strength elements (Ti, Nb, Hf, Zr) are closely linked to the detrital phase in marine sediments; Th is largely detrital but may be enriched in the hydrogenous Fe-Mn component of sediments; REE patterns are largely continental, but abundances are closely linked to fish debris phosphate; U is mostly detrital, but also dependent on the supply and burial rate of organic matter; Ba is linked to both biogenic barite and hydrothermal components; Sr is linked to carbonate phases. Thus, the important geochemical tracers follow the lithology of the sediments. Sediment lithologies are controlled in turn by a small number of factors: proximity of detrital sources (volcanic and continental); biological productivity and preservation of carbonate and opal; and sedimentation rate. Because of the link with lithology and the wealth of lithological data routinely collected for ODP and DSDP drill cores, bulk geochemical averages can be calculated to better than 30% for most elements from fewer than ten chemical analyses for a typical drill core (100-1000 m). Combining the geochemical systematics with convergence rate and other parameters permits calculation of regional compositional fluxes for subducting sediment. These regional fluxes can be compared to the compositions of arc volcanics to asses the importance of sediment subduction to arc volcanism. For the 70% of the trenches worldwide where estimates can be made, the regional fluxes also provide the basis for a global subducting sediment (GLOSS) composition and flux. GLOSS is dominated by terrigenous material (76 wt% terrigenous, 7 wt% calcium carbonate, 10 wt% opal, 7 wt% mineral-bound H2O+), and therefore similar to upper continental crust (UCC) in composition. Exceptions include enrichment in Ba, Mn and the middle and heavy REE, and depletions in detrital elements diluted by biogenic material (alkalis, Th, Zr, Hf). Sr and Pb are identical in GLOSS and UCC as a result of a balance between dilution and enrichment by marine phases. GLOSS and the systematics of marine sediments provide an independent approach to the composition of the upper continental crust for detrital elements. Significant discrepancies of up to a factor of two exist between the marine sediment data and current upper crustal estimates for Cs, Nb, Ta and Ti. Suggested revisions to UCC include Cs (7.3 ppm), Nb (13.7 ppm), Ta (0.96 ppm) and TiO2 (0.76 wt%). These revisions affect recent bulk continental crust estimates for La/Nb and U/Nb, and lead to an even greater contrast between the continents and mantle for these important trace element ratios. GLOSS and the regional sediment data also provide new insights into the mantle sources of oceanic basalts. The classical geochemical distinction between 'pelagic' and 'terrigenous' sediment sources is not valid and needs to be replaced by a more comprehensive understanding of the compositional variations in complete sedimentary columns. In addition, isotopic arguments based on surface sediments alone can lead to erroneous conclusions. Specifically, the Nd/Hf ratio of GLOSS relaxes considerably the severe constraints on the amount of sediment recycling into the mantle based on earlier estimates from surface sediment compositions.

(Table 1) Composition of bottom sediments and pore waters from the West Africa shelf

Organic and mineral phosphorus (P_org and P_min) have been determined in pore waters of terrigenous, biogenous, as well as weakly phosphatic and phosphatic sediments from the shelf of the West Africa (in 30 samples). Concentrations of P_min in the pore waters have been examined in close relation to grain size and chemical composition (amounts of P and N_org) of solid phase of the sediments. It has been demonstrated that among sands and coarse silts, maximum concentrations of P_min (up to 1.7 mg/l) in the pore waters have been observed in weakly phosphatic and phosphatic sediments rich in organic matter of the highly productive shelf of the Southwest Africa. Concentrations of P_min in the pore waters are most clearly associated with contents of N_org in the solid phase of the sediments (correlation coefficient R = 0.71) and P_org in the pore waters (R = 0.78).

(Table 1) Biomass (as energy) of different elements of the planktonic community in the Equatorial Pacific in the 0-150 m layer

An analysis was made of composition and content of nutrients, salts, particulate and dissolved organic matter, and various plankton groups in a series of samples collected by a 140-liter sampling bottle to depth up to 150 m at 4 equatorial stations between 97° and 154°W. Large and small phytoplankton, bacteria (aggregated and dispersed), heterotrophic flagellates, infusorians, radiolarians, foraminifers, fine filter-feeders, small and large, mostly herbivorous copepods, cyclopoids, predatory calanoids, and other predators were investigated separately. Trophic relations between these elements are established from personal and published data, and rate of their metabolism and some other physiological parameters are determined. Such functional characteristics as extent of satisfaction of food requirements of organisms belonging to various trophic groups, intensity of trophic relations, balance between production and consumption by individual elements of the community, ecological efficiency, and net and specific production of the groups distinguished, of individual trophic levels, of total zooplankton, and of the community as a whole are calculated. Variations of these characteristics along the equator with decreasing upwelling intensity are examined and their possible causes and mechanisms are discussed.

Multibeam and seismic survey, physical oceanography, and sea-bottom videos from the Bay of Biscay

We report the northernmost and deepest known occurrence of deep-water pycnodontine oysters, based on two surveys along the French Atlantic continental margin to the La Chapelle continental slope (2006) and the Guilvinec Canyon (2008). The combined use of multibeam bathymetry, seismic profiling, CTD casts and a remotely operated vehicle (ROV) made it possible to describe the physical habitat and to assess the oceanographic control for the recently described species Neopycnodonte zibrowii. These oysters have been observed in vivo in depths from 540 to 846 m, colonizing overhanging banks or escarpments protruding from steep canyon flanks. Especially in the Bay of Biscay, such physical habitats may only be observed within canyons, where they are created by both long-term turbiditic and contouritic processes. Frequent observations of sand ripples on the seabed indicate the presence of a steady, but enhanced bottom current of about 40 cm/s. The occurrence of oysters also coincides with the interface between the Eastern North Atlantic Water and the Mediterranean Outflow Water. A combination of this water mass mixing, internal tide generation and a strong primary surface productivity may generate an enhanced nutrient flux, which is funnelled through the canyon. When the ideal environmental conditions are met, up to 100 individuals per m² may be observed. These deep-water oysters require a vertical habitat, which is often incompatible with the requirements of other sessile organisms, and are only sparsely distributed along the continental margins. The discovery of these giant oyster banks illustrates the rich biodiversity of deep-sea canyons and their underestimation as true ecosystem hotspots.

Chemical composition of bottom sediments and interstitial waters from DSDP Sites 252, 285, 315, 317, 336, and 386

Six Deep Sea Drilling Project (DSDP) Sites (252, 285, 315, 317, 336, 386) were examined for the chemical composition of the dissolved salts in interstitial waters, the oxygen isotopic composition of the interstitial waters, and the major ion composition of the bulk solid sediments. An examination of the concentration-depth profiles of dissolved calcium, magnesium, potassium, and H218O in conjunction with oxygen isotope mass balance calculations confirms the hypothesis that in DSDP pelagic drill sites concentration gradients in Ca. Mg. K, and H218O are largely due to alteration reactions occurring in the basalts of Layer 2 and to alteration reactions involving volcanic matter dispersed in the sediment column. Oxygen isotope mass balance calculations require substantial alteration of Layer 2 (up to 25% of the upper 1000 m). but only minor exchange of Ca, Mg, and K occurs with the overlying ocean. This implies that alteration reactions in Layer 2 are almost isochemical.

Hydrocarbons in particulate matter and bottom sediments from the north Caspian Sea shelf

Data are presented on content and composition of hydrocarbons (HC) (aliphatic AHC and polyaromatic PAH) in filtered particulate matter and in the surface layer of bottom sediments from the northern shelf of the Caspian Sea and related to data on their contents in the Volga River estuary. Because of transformation and precipitation of anthropogenic and natural compounds, HC composition in particulate matter and bottom sediments undergoes transformations caused by mixing of fresh and saline waters (in bottom sediments, within concentration ranges 70.4-4557.9 µg/g for AHC and 3.8-4800 ng/g for PAH). It was found that the greatest concentrating of HC proceeds in the region of the avalanche sedimentation, and their contents are independent of grain-size types of bottom sediments. Anthropogenic HC (oil and pyrogenous) do not get over the marginal filter of the Volga River and do not pass to the open part of the sea.

Rare earth and other element contents in surface layer bottom sediments and ferromanganese nodules along the Transatlantic profile

Behavior of rare earth elements (REE) and Th is studied along the Transatlantic transect at 22°N. It is shown that both REE and Th contents relative to Al (the most lithogenic element) increase toward the pelagic region. The increasing trend becomes more complicated due to variations in content of biogenic calcium carbonate that acts as a diluting component in sediments. REE composition varies symmetrically relative to the Mid-Atlantic Ridge (MAR) emphasizing weak hydrothermal influence on sediments of the ridge axis, although the well-known criteria for hydrothermal contribution, such as Al/(Al+Mn+Fe) and (Fe+Mn)/Ti, do not reach critical values. Variations in REE content and composition allowed to distinguish the following five sediment zones in the transect: (I) terrigenous sediments of the Nares abyssal plain; (II) pelagic sediments of the North American Basin; (III) carbonate ooze of the MAR axis; (IV) pelagic sediments of the Canary Basin; and (V) terrigenous clay and calcareous mud of the African continental slope and slope base. Ferromanganese nodules of the hydrogenous type with extremely high Ce (up to 1801 ppm) and Th (up to 138 ppm) contents occur in pelagic sediments. It is ascertained that P, REE, and Th contents depend on Fe content in Atlantic sediments. Therefore, one can suggest that only minor amount of phosphorus is bound with bone debris. Low concentration of bone debris phosphorus is a result of relatively high sedimentation rates in the Atlantic Ocean, as compared with those in pelagic regions of the Pacific Ocean.