Updated bathymetric chart of the East Aral Sea

The Aral Sea is located in an arid region with much sand and salt deposits in the surrounding barren open land. Hence, significant displacements of sediments into the lakebed by the action of wind, water, gravity, or snow are likely. The bathymetry of the lake was last observed in the 1960s, and within the last half century, the structure of the lakebed has changed. Based on satellite observations of the temporal changes of shoreline (Landsat optical remote sensing) and water level (multi-mission satellite altimetry) over more than one decade an updated bathymetric chart for the East Basin of the Aral Sea has been generated. During this time, the geometry of the shallow East Basin experienced strong fluctuations due to the occurrence of periods of drying and strong inflow. By the year 2014 the East Basin fell dry. The dynamic behavior of the basin allowed for estimating the lake's bathymetry from a series of satellite-based information. The river mouth made its impression in the present East Aral Sea, because its shrinking led to the inflow of much sediment into the lake's interior. In addition, salt deposits along the shorelines increased the corresponding elevation, a phenomenon that is more pronounced in the reduced lakebed because of increased salinity. It must be noted that height estimates from satellite altimetry were only possible down to a minimum elevation of 27 m above sea level due to a lack of reliable altimetry data over the largely reduced water surface. In order to construct a complete bathymetric chart of the lakebed of the East Aral Sea heights below 27 m were obtained solely from Landsat optical images following the SRB (Selected Region Boundary) approach as described by Singh et al. (2015).

Coral oxygen isotope and Sr/Ca data from the Northern Gulf of Aqaba (Red Sea)

The last interglacial period (about 125,000 years ago) is thought to have been at least as warm as the present climate (Kukla et al., 2002, doi:10.1006/qres.2001.2316). Owing to changes in the Earth's orbit around the Sun, it is thought that insolation in the Northern Hemisphere varied more strongly than today on seasonal timescales (Berger, 1987, doi:10.1175/1520-0469(1978)035<2362:LTVODI>2.0.CO;2), which would have led to corresponding changes in the seasonal temperature cycle (Montoya et al., 2000, doi:10.1175/1520-0442(2000)013<1057:CSFKBW>2.0.CO;2). Here we present seasonally resolved proxy records using corals from the northernmost Red Sea, which record climate during the last interglacial period, the late Holocene epoch and the present. We find an increased seasonality in the temperature recorded in the last interglacial coral. Today, climate in the northern Red Sea is sensitive to the North Atlantic Oscillation (Felis et al., 2000 doi:10.1029/1999PA000477; Rimbu et al., 2001, doi:10.1029/2001GL013083), a climate oscillation that strongly influences winter temperatures and precipitation in the North Atlantic region. From our coral records and simulations with a coupled atmosphere-ocean circulation model, we conclude that a tendency towards the high-index state of the North Atlantic Oscillation during the last interglacial period, which is consistent with European proxy records (Zagwijn, 1996, doi:10.1016/0277-3791(96)00011-X; Aalbersberg and Litt, 1998, doi:10.1002/(SICI)1099-1417(1998090)13:5<367::AID-JQS400>3.0.CO;2-I; Klotz et al., 2003, doi:10.1016/S0921-8181(02)00222-9), contributed to the larger amplitude of the seasonal cycle in the Middle East.

Biomarkers in surface sediments from the Ob and Yenisei estuaries and the southern Kara Sea

Organic-geochemical bulk parameter (Total organic carbon contents, C/N ratios and d13Corg values), biogenic opal and biomarkers (n-alkanes, fatty acids, sterols and amino acids) were determined in surface sediments from the Ob and Yenisei estuaries and the adjacent southern Kara Sea. Maximum TOC contents were determined in both estuaries, reaching up to 3 %. Relatively high C/N ratios around 10, light d13Corg values of -26.5 per mil (Yenisei) and -28 to -28.7 per mil (Ob), and maximum concentrations of long-chain n-alkanes of up to about 10 µg/g Sed clearly show the predominance of terrigenous organic matter in the sediments from the estuaries. Towards the open Kara Sea, all p arameters indicate a decrease in terrigenous organic carbon. Brassicasterol as well as the short-chain n-alkanes parallel this trend, suggesting that these biomarkers are probably also related to a terrigenous (fresh-water phytoplankton) source. Amino acid spectra show characteristic trends from the Yenisei Estuary to the open Kara Sea revealing increasing state of degradation. Sedimentary organic matter in the Yenisei Estuary is relatively less degraded compared to the Ob Estuary and the open Kara Sea.

Zoobenthos and oceanographical parameters in the Kemskaya Guba (Bay) - estuary of the Kem' River entering the Onega Bay, White Sea

Data on distribution of zoobenthos in the Kemskaya Guba (or Kemskaya Bay - the estuary of the Kem' River entering the Onega Bay of the White Sea), which is strongly influenced by river runoff, are presented. The number of species at sampling stations varied from 4 to 65. Density of communities and zoobenthos biomass varied from 342±68 to 4293±96 #/m**2 and from 0.418±0.081 to 1975.22±494.36 g/m**2, respectively. Shannon index values varied between 1.19 to 4.7 bit/ind. At the upper part of the estuary, detritivores dominated, while in the central part and at outlets sestonophages prevailed. Changes in quantitative parameters of the zoobenthos along gradient of water salinity were traced, and relations of these parameters with seven other environmental factors were revealed. It was found that species composition, biodiversity, and trophic structure of the zoobenthos significantly correlated with some of parameters mentioned above. Multiple regression analysis was used to assess combined effect of factors, and it revealed which of them played a determining role in Kemskaya Guba: for species composition - depth, water color, and total concentration of suspended matter; for number of species - contents of <0.01 mm grain size (pelite) fraction and organic carbon in bottom sediments. Biomass depended on water salinity, water chromaticity, and organic carbon contents in bottom sediments and suspended matter. Values of the Shannon index of diversity are determined by water color, and contents of organic carbon and pelite fraction in bottom sediments. Calculations of ecological stress values revealed two zones with unstable state of the zoobenthos.

Hydrology dataset based on 111 CTD stations in the North Aegean Sea during June 1998 from the project INTERREGAEGEAN

The combination of two research projects offered us the opportunity to perform a comprehensive study of the seasonal evolution of the hydrological structure and the circulation of the North Aegean Sea, at the northern extremes of the eastern Mediterranean. The combination of brackish water inflow from the Dardanelles and the sea-bottom relief dictate the significant differences between the North and South Aegean water columns. The relatively warm and highly saline South Aegean waters enter the North Aegean through the dominant cyclonic circulation of the basin. In the North Aegean, three layers of distinct water masses of very different properties are observed: The 20-50 m thick surface layer is occupied mainly by Black Sea Water, modified on its way through the Bosphorus, the Sea of Marmara and the Dardanelles. Below the surface layer there is warm and highly saline water originating in the South Aegean and the Levantine, extending down to 350-400 m depth. Below this layer, the deeper-than-400 m basins of the North Aegean contain locally formed, very dense water with different i/S characteristics at each subbasin. The circulation is characterised by a series of permanent, semi-permanent and transient mesoscale features, overlaid on the general slow cyclonic circulation of the Aegean. The mesoscale activity, while not necessarily important in enhancing isopycnal mixing in the region, in combination with the very high stratification of the upper layers, however, increases the residence time of the water of the upper layers in the general area of the North Aegean. As a result, water having out-flowed from the Black Sea in the winter, forms a separate distinct layer in the region in spring (lying between "younger" BSW and the Levantine origin water), and is still traceable in the water column in late summer.

Amino acid in Deep Sea Drilling Project cores

Several amino acid diagenetic reactions, which take place in the deep-sea sedimentary environment, were investigated, using various Deep Sea Drilling Project (DSDP) cores. Initially it was found that essentially all the amino acids in sediments are bound in peptide linkages; but, with increasing age, the peptide bonds undergo slow hydrolysis that results in an increasingly larger fraction of amino acids in the free state. The hydrolysis half-life in calcareous sediments was estimated to be ~1-2 million years, while in non-carbonate sediment the hydrolysis rate may be considerably slower. The amino acid compositions and the extent of racemization of several amino acids were determined in various fractions isolated from the sediments. These analyses demonstrated that the mechanism, kinetics, and rate of amino acid diagenesis are highly dependent upon the physical state (i.e., free, bound, etc.) in which the amino acids exist in the sedimentary environment. In the free state, serine and threonine were found to decompose primarily by a dehydration reaction, while in the bound state (residue or HCl-insoluble fraction) a reversible aldol-cleavage reaction is the main decomposition pathway of these amino acids. The change in amino acid composition of the residue fraction with time was suggested to be due to the hydrolysis of peptide bonds, while in foraminiferal tests the compositional changes over geological time are the result of various decomposition reactions. Reversible first-order racemization kinetics are not observed for free amino acids in sediments. The explanation for these anomalous kinetics involves a complex reaction series which includes the hydrolysis of peptide bonds and the very rapid racemization of free amino acids. The racemization rates of free amino acids in sediments were found to be many orders of magnitude faster than those predicted from elevated temperature experiments using free amino acids in aqueous solution. The racemization rate enhancement of free amino acids in sediments may be due to the catalysis of the reaction by trace metals. Reversible first-order kinetics are followed for amino acids in the residue fraction isolated from sediments; the rate of racemization in this fraction is slower than that predicted for protein-bound amino acids. Various applications of amino acid diagenetic reactions are discussed. Racemization and the decomposition reaction of serine and threonine can both be used, with certain limitations, to make rough age estimates of deep-sea sediments back to several million years. The extent of racemization in foraminiferal tests which have been dated by some other independent technique can be used to estimate geothermal gradients, and thus heat flows, and to evaluate the bottom water temperature history in certain oceanic areas.

Acute survivorship of the deep-sea coral Lophelia pertusa from the Gulf of Mexico under acidification,warming,and deoxygenation

Changing global climate due to anthropogenic emissions of CO2 are driving rapid changes in the physical and chemical environment of the oceans via warming, deoxygenation, and acidification. These changes may threaten the persistence of species and populations across a range of latitudes and depths, including species that support diverse biological communities that in turn provide ecological stability and support commercial interests. Worldwide, but particularly in the North Atlantic and deep Gulf of Mexico, Lophelia pertusa forms expansive reefs that support biological communities whose diversity rivals that of tropical coral reefs. In this study, L. pertusa colonies were collected from the Viosca Knoll region in the Gulf of Mexico (390 to 450 m depth), genotyped using microsatellite markers, and exposed to a series of treatments testing survivorship responses to acidification, warming, and deoxygenation. All coral nubbins survived the acidification scenarios tested, between pH of 7.67 and 7.90 and aragonite saturation states of 0.92 and 1.47. However, calcification generally declined with respect to pH, though a disparate response was evident where select individuals net calcified and others exhibited net dissolution near a saturation state of 1. Warming and deoxygenation both had negative effects on survivorship, with up to 100% mortality observed at temperatures above 14ºC and oxygen concentrations of approximately 1.5 ml·l-1. These results suggest that, over the short-term, climate change and OA may negatively impact L. pertusa in the Gulf of Mexico, though the potential for acclimation and the effects of genetic background should be considered in future research.

Primary production within the euphotic layer of the Norwegian Sea in July 1997: measurements by different methods

Results of primary production measurements obtained by different methods are presented. These methods are radiocarbon and oxygen modifications of the flask method, as well as fluorometric procedure with a PrimProd submersible probing fluorometer (produced at the Biological Department, Moscow State University). The research was carried out during a complex expedition aboard R/V Akademik Boris Petrov to the Norwegian Sea in July, 1977. Distributions of primary production values measured by different methods were correlated with other oceanographic data. Then a comparison of obtained values by the above-mentioned methods was performed.

Sea ice thickness from airborne electromagnetic (EM) induction sounding acquired from fixed-wing aircraft POLAR 5 surveys from several airports in Spitsbergen, Greenland, Canada and Alaska

While summer Arctic sea-ice extent has decreased over the past three decades, it is subject to large interannual and regional variations. Methodological challenges in measuring ice thickness continue to hamper our understanding of the response of the ice-thickness distribution to recent change, limiting the ability to forecast sea-ice change over the next decade. We present results from a 2400 km long pan-Arctic airborne electromagnetic (EM) ice thickness survey in April 2009, the first-ever large-scale EM thickness dataset obtained by fixed-wing aircraft over key regions of old ice in the Arctic Ocean between Svalbard and Alaska. The data provide detailed insight into ice thickness distributions characteristic for the different regions. Comparison with previous EM surveys shows that modal thicknesses of old ice had changed little since 2007, and remained within the expected range of natural variability.