(Table 1) Age, sex, length, girth and blubber thickness and content of ringed seals (Pusa hispida) in Kongsfjorden in 2000

This study of vertical fatty acid profiles, based on analysis of 58 fatty acids sampled at 3-mm intervals throughout the blubber column of a model marine mammal, the ringed seal (Pusa hispida), revealed three chemically distinct layers. The average depths of the outer and inner layers were quite consistent (~1.5 and ~1 cm, respectively). Consequently, the middle layer varied greatly in thickness, from being virtually absent in the thinnest animals to 2.5 cm thick in the fattest. The relative consistencies of the thickness and composition of the layers as well as the nature of the fatty acids making up each layer support the generally assumed function of the various layers: (1) the outer layer is primarily structural and thermoregulatory, (2) the inner layer is metabolically active with a fatty acid composition that is strongly affected by recent/ongoing lipid mobilization/deposition, and (3) the middle layer is a storage site that contracts and expands with food availability/consumption. The remarkable dynamics of the middle layer along with the discrete pattern of stratification found in the vertical fatty acid profiles have important implications for methodological sampling design for studies of foraging ecology and toxicology based on analyses of blubber of marine mammals.

The Fohsella chronocline in middle Miocene sediments from the Ontong Java Plateau, Pacific Ocean

Micropaleontologists have traditionally recognized the mid-Miocene Fohsella lineage as a flagship for phyletic gradualism within the planktic foraminifera. However, study of a deep-sea record from the western equatorial Pacific (ODP Site 806) reveals that coiling ratios within this clade suddenly (<5 kyr) shift after a prolonged, ancestral state of near randomness (~50%) to a transient phase (13.42-13.43 Ma) of dextral dominance (~75%) immediately following the first common occurrence of keeled fohsellids. This brief period of dextral dominance was abruptly (<5 kyr) succeeded by an irreversible change to sinistral dominance (~96%). Fohsellid abundances decline markedly through the interval in which the sinistral preference is established. The shift to sinistrality (13.42 Ma) predated the deepening of fohsellid depth ecology by ~240-488 kyr, indicating that these two events were unrelated. This view is supported by a lack of delta 18O evidence for depth-habitat differences between the two chiral forms, which refutes the notion that sinistral fohsellids were "pre-adapted" for ensuing hydrographic change because they occupied a deeper depth habitat than their dextral counterparts. Planktic foraminiferal assemblages become strongly oligotrophic in character through the interval in which the fohsellid delta 18O increase is recorded, indicating that the migration to deeper depths was fostered by an expansion of the mixed layer in the western equatorial Pacific. Salient aspects of this brief, but conspicuous faunal change are a marked increase in the abundance of symbiont-bearing globigerinoidids, a concomitant collapse of local Jenkinsella mayeri/siakensis populations, and reduced fohsellid abundances. The rapid and permanent nature of the Fohsella sinistral shift provides a distinct, unequivocal datum that may prove useful for correlating mid-Miocene sections throughout the Caribbean Sea and tropical regions in the western sectors of the Pacific and Atlantic. The coiling ratio changes that occurred during the evolution of the Fohsella chronocline probably reflect changing population dynamics between cryptic genotypes with different coiling preferences.

Benthic foraminiferal composition at the inner wall of the Middle America Trench, Costa Rica

The sediments of Deep Sea Drilling Project Site 565 and University of Texas Marine Science Institute Cores IG-24-7-38 to -42 taken on the landward slope of the Middle America Trench exhibit characteristics of material subject to reworking during downslope mass flow. These characteristics include a generally homogeneous texture, lack of sedimentary structures, pervasive presence of a penetrative scaly fabric, and presence of transported benthic foraminifers. Although these features occur throughout the sediments examined, trends in bulk density, porosity, and water content, and abrupt shifts in these index physical properties and in sediment magnetic properties at Site 565 indicate that downslope sediment creep is presently most active in the upper 45 to 50 m of sediment. It cannot be determined whether progressive dewatering of sediment has brought the material at this depth to a plastic limit at which sediment can no longer flow (thus resulting in its accretion to the underlying sediments) or whether this depth represents a surface along which slumping has occurred. We suspect both are true in part, that is, that mass movements and downslope reworking accumulate sediments in a mobile layer of material that is self-limiting in thickness.

Carbon and Lead chemistry of sediments from the Middle Atlantic Bight

A mass budget was constructed for organic carbon on the upper slope of the Middle Atlantic Bight, a region thought to serve as a depocenter for fine-grained material exported from the adjacent shelf. Various components of the budget are internally consistent, and observed differences can be attributed to natural spatial variability or to the different time scales over which measurements were made. The flux of organic carbon to the sediments in the core of the depocenter zone, at a water depth of 1000 m, was measured with sediment traps to be 65 mg C m**-2 day**-1, of which 6-24 mg C m**-2 day**-1 is buried. Oxygen fluxes into the sediments, measured with incubation chambers attached to a free vehicle lander, correspond to total carbon remineralization rates of 49-70 mg C m**-2 day**-1. Carbon remineralization rates estimated from gradients of Corg within the mixed layer, and from gradients of dissolved ammonia and phosphate in pore waters, sum to only 4-6 mg C m**-2 day**-1. Most of the Corg remineralization in slope sediments is mediated by bacteria and takes place within a few mm of the sediment-water interface. Most of the Corg deposited on the upper slope sediments is supplied by lateral transport from other regions, but even if all of this material were derived from the adjacent shelf, it represents <2% of the mean annual shelf productivity. This value is further lowered by recognizing that as much as half of the Corg deposited on the slope is refractory, having originated by reworking from older deposits. Refractory Corg arrives at the sea bed with an average 14C age 600-900 years older than the pre-bomb 14C age of DIC in seawater, and has a mean life in the sediments with respect to biological remineralization of at least 1000 years. Labile carbon supplied to the slope, on the other hand, is rapidly and (virtually) completely remineralized, with a mean life of < 1 year. Carbon-14 ages of fine-grained carbonate and organic carbon present within the interstices of shelf sands are consistent with this material acting as a source for the old carbon supplied to the slope. Winnowing and export of reworked carbon may contribute to the often-described relationship between organic carbon preservation and accumulation rate of marine sediments.

Composition of surface layer bottom sediments from the Kem' River estuary, White Sea

Based on grain-size, mineralogical and chemical analyses of samples collected in cruises of R/V Ekolog (Institute of Northern Water Problems, Karelian Research Centre of RAS, Petrozavodsk) in 2001 and 2003 regularities of chemical element distribution in surface layer bottom sediments of the Kem' River Estuary in the White Sea were studied. For some toxic elements labile and refractory forms were determined. Correlation analysis was carried out and ratios Me/Al were calculated as proxies of terrigenous contribution. Distribution of such elements as Fe, Mn, Zn, Cr, Ti was revealed to be influenced by natural factors, mainly by grain size composition of bottom sediments. These metals have a tendency for accumulation in fine-grained sediments with elevated organic carbon contents. Distribution of Ni is different from one of Fe, Mn, Zn, Cr, Ti. An assumption was made that these distinctions were caused by anthropogenic influence.

Ash layer characteristics and major element oxide content of glasses from ODP Sites 162-982 and 162-985

The Cenozoic volcanic activity on Iceland has been recorded in North Atlantic sediments drilled during several Ocean Drilling Program (ODP)/Deep Sea Drilling Project legs (Legs 104, 151, 152, 162, and 163). Leg 162 (North Atlantic-Arctic Gateways II) recovered ash layers at Sites 982, 985, and 907 (Jansen, Raymo, Blum, et al., 1996, doi:10.2973/odp.proc.ir.162.1996). The revisited Site 907 was first drilled during Leg 151, and the ash from this site has been described in detail by Lacasse et al. (1996, doi:10.2973/odp.proc.sr.151.122.1996) and Werner et al. (1996, doi:10.2973/odp.proc.sr.151.123.1996). Site 982 is located within the Hatton-Rockall Basin on the Rockall Plateau, which is situated west of the British Isles. Site 985 is located northeast of Iceland at the foot of the eastern slope of the Iceland Plateau, adjacent to the Norwegian Basin. Here we report chemical analyses of Neogene tephra layers from Holes 982A, 983B, 982C, 985A, and 985B. The sedimentary sequence at Site 982 spans the lower Miocene-Holocene; Site 985 recovered sediments spanning the upper Oligocene-Holocene. Twenty-two distinct ash layers and ash-bearing sediments were sampled in Holes 982A-982C (Cores 162-982A-16H through 24H, 162-982B-14H through 56X, and 162-982C-15H through 27H), and 59 ash layers were sampled in Holes 985A and 985B (Cores 162-985A-11H through 59X, and 162-985B-11H through 14H). Almost 50% of the sampled ash is strongly altered (predominantly from Site 985). A cluster of altered thin layers in the lower Pliocene of Site 985 (top of Unit III) is remarkable.

Major oxides for tektites and for conglomerate clast of the Upper Eocene ejecta-bearing layer of ODP Hole 150-904A (Table 1)

Evidence for the Chesapeake Bay Crater as the source for New Jersey continental margin ejecta is provided by fine-grained tektites and coarse-grained unmelted ejecta. The Upper Eocene ejecta deposit, now demonstrated to be part of the North American strewn field, occurs on the New Jersey continental margin at Ocean Drilling Program (ODP) Sites 904 and 903. The mineralogy, major oxide composition of the ejecta materials, and biostratigraphic age of the enclosing sediments link the origin of these ejecta to the recently recognized Chesapeake Bay impact crater, located only 330 km away. Sediments associated with the ejecta provide information about the dynamics of impact events. The 35-cm-thick ejecta-bearing layer can be subdivided into three subunits that indicate a sequence of events. Bottom subunit III documents sediment failure and deposition of gravel-sized fragments, middle subunit II records deposition of abundant sand-sized ejecta by gravity settling, and upper subunit I contains a 12-cm-thick sedimentary deposit containing rare silt-sized tektites and evidence of waning currents. These events are interpreted by linking sediment deposition to seismic ground motion and subsequent tsunami waves triggered by both the Chesapeake Bay impact and slope failures.

Reconstruction of sea-surface conditions at middle to high latitudes of the Northern Hemisphere

A new calibration database of census counts of organic-walled dinoflagellate cyst (dinocyst) assemblages has been developed from the analyses of surface sediment samples collected at middle to high latitudes of the Northern Hemisphere after standardisation of taxonomy and laboratory procedures. The database comprises 940 reference data points from the North Atlantic, Arctic and North Pacific oceans and their adjacent seas, including the Mediterranean Sea, as well as epicontinental environments such as the Estuary and Gulf of St. Lawrence, the Bering Sea and the Hudson Bay. The relative abundance of taxa was analysed to describe the distribution of assemblages. The best analogue technique was used for the reconstruction of Last Glacial Maximum (LGM) sea-surface temperature and salinity during summer and winter, in addition to sea-ice cover extent, at sites from the North Atlantic (n=63), Mediterranean Sea (n=1) and eastern North Pacific (n=1). Three of the North Atlantic cores, from the continental margin of eastern Canada, revealed a barren LGM interval, probably because of quasi-permanent sea ice. Six other cores from the Greenland and Norwegian seas were excluded from the compilation because of too sparse assemblages and poor analogue situation. At the remaining sites (n= 54), relatively close modern analogues were found for most LGM samples, which allowed reconstructions. The new LGM results are consistent with previous reconstructions based on dinocyst data, which show much cooler conditions than at present along the continental margins of Canada and Europe, but sharp gradients of increasing temperature offshore. The results also suggest low salinity and larger than present contrasts in seasonal temperatures with colder winters and more extensive sea-ice cover, whereas relatively warm conditions may have prevailed offshore in summer. From these data, we hypothesise low thermal inertia in a shallow and low-density surface water layer.

Middle Miocene stable carbon and oxygen isotope record of foraminifera of ODP Hole 120-747A

Paleoceanographic variability at southern high latitude Ocean Drilling Program (ODP) Site 747 was investigated in this study through the interval which spans the Middle Miocene Climate Transition (MMCT). Between 15.0 and 12.2 million years ago (Ma), foraminiferal d18O records derived from both benthic (Cibicidoides spp.) and planktonic taxa (Globorotalia praescitula and Globigerina bulloides) reveal a history of changes in water column thermal and salinity structure and a strong imprint of seasonality. Prior to the MMCT, in the interval between 14.35 and 13.9 Ma, G. bulloides displays relatively high d18O values similar to those of G. praescitula, interpreted to indicate weakening of the thermocline and/or increased seasonality with cooler early-spring and/or late-fall temperatures. Following this interval, G. bulloidesd18O values diverge significantly from benthic and G. praescitula values, with G. bulloides values remaining relatively low for at least 600 kyr following the benthic foraminiferal d18O shift during the MMCT at ~13.9 Ma. This divergence in d18O records occurs in direct association with the Mi3 cooling and glaciation event and may suggest: (1) a strengthening of the vertical temperature gradient, with greater cooling of deep waters than surface waters, (2) changes in the depth habitat of G. bulloides, (3) changes in the dominant season of G. bulloides calcification, (4) modification of surface-water d18O values in association with enhanced sea-ice formation, (5) increased surface-water carbonate ion concentration, and/or (6) a significant decrease in surface-water salinity across the MMCT. The first of these possible scenarios is not likely, particularly in light of recent Mg/Ca evidence for significant surface-water cooling in the Southern Ocean associated with the MMCT. Of the remaining possibilities, we favor a change in surface salinity to explain the observed trends in d18O values and hypothesize that surface salinity may have decreased by up to 2 salinity units at ~13.9 Ma. In this scenario, the development of a lower-salinity Antarctic surface layer coincided with regional cooling of both surface and deep waters of the Southern Ocean during the Mi3 glaciation of East Antarctica, and contributed into the dominance of Neogloboquadrina spp. between 13.8 and 13.2 Ma. Additionally, the distinct patterns observed in planktonic foraminiferal d18O records spanning the MMCT correspond with changes in the vertical d13C gradient between planktonic and benthic foraminiferal records and major changes in planktonic foraminiferal assemblages at Site 747, providing further evidence of the environmental significance of this climatic transition.

Concentration and production of bacteria and bacterial destruction in the photic layer of the Sodruzhestvo Sea area, Southern Ocean

Bacterioplankton in the photic layer of the Sodruzhestvo Sea area and adjoining waters consists in summer primarily of cocci, with fractions smaller than 2 ?m predominating. The average abundance and biomass of microorganisms are 427 thousand cells/ml and 438 mg C/m**2, with ranges of 150-1770 thousand cells/ml and 221-1146 mg C/m**2. The average daily production and bacterial destruction increase from 49 and 104 mg C/m**2 at the beginning of the growth period to 85 and 180 mg C/m**2 in the middle of the period and remain at this level till the end. Despite low rate of increase (daily P/B coefficient averages 0.12), because of its high abundance bacterioplankton in Antarctic waters plays a major role in destruction of organic matter, accounting for 60-85% of energy consumed by heterotrophs.

Mineralogy and geochemistry of Mg-phyllosilicates from Middle Valley, northern Juan de Fuca Ridge

We present results of a detailed mineralogical and geochemical study of the progressive hydrothermal alteration of clastic sediments recovered at ODP Site 858 in an area of active hydrothermal venting at the sedimented, axial rift valley of Middle Valley (northern Juan de Fuca Ridge). These results allow a characterization of newly formed phyllosilicates and provide constraints on the mechanisms of clay formation and controls of mineral reactions on the chemical and isotopic composition of hydrothermal fluids. Hydrothermal alteration at Site 858 is characterized by a progressive change in phyllosilicate assemblages with depth. In the immediate vent area, at Hole 858B, detrital layers are intercalated with pure hydrothermal precipitates at the top of the section, with a predominance of hydrothermal phases at depth. Sequentially downhole in Hole 858B, the clay fraction of the pure hydrothermal layers changes from smectite to corrensite to swelling chlorite and finally to chlorite. In three pure hydrothermal layers in the deepest part of Hole 858B, the clay minerals coexist with neoformed quartz. Neoformed and detrital components are clearly distinguished on the basis of morphology, as seen by SEM and TEM, and by their chemical and stable isotope compositions. Corrensite is characterized by a 24 Å stacking sequence and high Si- and Mg-contents, with Fe/(Fe+Mg) ratio of = 0.08. We propose that corrensite is a unique, possibly metastable, mineralogical phase and was precipitated directly from seawater-dominated hydrothermal fluids. Hydrothermal chlorite in Hole 858B has a stacking sequence of 14 Å with Fe/(Fe+Mg) ratios of ? 0.35. The chemistry and structure of swelling chlorite suggest that it is a corrensiteychlorite mixed-layer phase. The mineralogical zonation in Hole 858B is accompanied by a systematic decrease in d18O, reflecting both the high thermal gradients that prevail at Site 858 and extensive sediment-fluid interaction. Precipitation of the Mg-phyllosilicates in the vent region directly controls the chemical and isotopic compositions of the pore fluids. This is particularly evident by decreases in Mg and enrichments in deuterium and salinity in the pore fluids at depths at which corrensite and chlorite are formed. Structural formulae calculated from TEM-EDX analyses were used to construct clay-H2O oxygen isotope fractionation curves based on oxygen bond models. Our results suggest isotopic disequilibrium conditions for corrensite-quartz and swelling chlorite-quartz precipitation, but yield an equilibrium temperature of 300° C ± 30° for chlorite-quartz at 32 m below the surface. This estimate is consistent with independent estimates and indicates steep thermal gradients of 10-11°/m in the vent region.

Abundance and biomass of planktonic diatom Proboscia alata and associated species, chlorophyll a, organic carbon and nitrogen concentrations in waters over the Bering Sea middle shelf in August 2001

During most of the vegetation season from late May to early September large-sized diatom alga Proboscia alata forms local patches with high abundances and biomasses in different oceanographic domains of the eastern Bering Sea shelf. For 0-25 m layer average abundance and biomass of species in these patches are 700000 cells/l and 5 g/m**3 (wet weight), while corresponding estimates for the layer of maximal species concentrations are 40000000 cells/l and 38 g/m**3 (wet weight) or 1.6 g C/m**3. These levels of abundance and biomass are typical for the spring diatom bloom in the region. Outbursts of P. alata mass development are important for the carbon cycle in the pelagic zone of the shelf area in the summer season. The paradox of P. alata summertime blooms over the middle shelf lies in their occurrences against the background of the sharp seasonal pycnocline and deficiency in nutrients in the upper mixed layer. Duration of the outbursts in P. alata development is about two weeks and size of patches with high abundances can be as large as 200 km across. Degradation of the P. alata summertime outbursts may occur during 4-5 days. Rapid sinking of cells through the seasonal pycnocline results in intense transport of organic matter to bottom sediments. One of possible factors responsible for rapid degradation of the blooms is affect on the population by ectoparasitic flagellates. At terminal stages of the P. alata blooms percentage of infected cells can reach 70-99%.

Middle Miocene evolution and stable isotope ratios of Globorotalia (Fohsella) in the western equatorial Pacific

Evolution of the planktic foraminiferal lineage Globorotalia (Fohsella) occurred during the Miocene between 23.7 and 11.8 Ma and forms the basis for stratigraphic subdivision of the early middle Miocene (Zones N 10 through N 12). Important morphologic changes within the G. (Fohsella) lineage included a marked increase in test size, a transition from a rounded to an acute periphery, and the development of a keel in later forms. We found that the most rapid changes in morphology of G. (Fohsella) occurred between 13 and 12.7 Ma and coincided with an abrupt increase in the delta18O ratios of shell calcite. Comparison of isotopic results of G. (Fohsella) with other planktic foraminifers indicate that delta18O values of the lineage diverge from surface-dwelling species and approach deep-dwelling species after 13.0 Ma, indicating a change in depth habitat from the surface mixed layer to intermediate depth near the thermocline. Isotopic and faunal evidence suggests that this change in depth stratification was associated with an expansion of the thermocline in the western equatorial Pacific. After adapting to a deeper water habitat at 13.0 Ma, the G. (Fohsella) lineage became extinct abruptly at 11.8 Ma during a period when isotopic and faunal evidence suggest a shoaling of the thermocline. Following the extinction of G. (Fohsella), the ecologic niche of the lineage was filled by the Globorotalia (Menardella) group, which began as a deep-water form and later evolved to an intermediate-water habitat. We suggest that the evolution of G. (Fohsella) and G. (Menardella) were tightly linked to changes in the structure of the thermocline in the western equatorial Pacific.