Isotopic composition of carbon in organic matter of sediments and particulate matter from the Northwest Pacific

A study was made of isotopic composition of carbon in lipids found in three samples of separate particulates and in eight bottom sediment samples collected in a from the Simushir Island towards the open Pacific Ocean. Average d13C of lipids from particulates was 2.3 per mil lower than one of sediments. Humic acids from sediments are the most isotopically heavy fraction (d13C = -21.2 per mil). Isotopic composition of carbon in lipids depended on their total content in samples and on composition of sediments. Formation of isotopically heavy lipids in the surface layer of sediments may be associated with biogeochemical resynthesis of humic acids.

Ingestion rate and egg production of copepods collected in the upper 100m in the eastern Mediterranean Sea in March and April 2008 during SES_GR1

The phytoplankton dataset is based on samples taken during March-April 2008 in Libyan Sea, Southern Aegean Sea and Northern Aegean Sea. Ingestion rates were estimated from experiments performed at all the third priority stations during the cruise according to DoW of Sesame project. Copepods for the experiments were obtained with slow non-quantitative tows from the upper 100 m layer of the water column using 200 µm mesh size nets fitted with a large non-filtering cod end. For the grazing experiments we used the following copepod species: Calanus helgolandicus and Centropages typicus according to the relevant reference (Bamstedt et al. 2000). Copepod clearance rates on ciliates were calculated according to Frost equations (Frost 1972). Ingestion rates were calculated by multiplying clearance rates by the initial standing stocks (Bamstedt et al. 2000). Egg production rates of the dominant calanoid copepods were determined by incubation of fertilised females (eggs/female/day) collected in the 0-100m layer. Copepod egg production was measured for the copepods Eucalanus monachus, Centropages typicus and Calanus helgolandicus. On board experiments for the estimation of copepod egg production were taken place. For the estimation of copepod production (mg/m**2/day), lengths (copepods and eggs) were converted to body carbon (Hopcroft et al., 1998) and production was estimated from biomass and weight-specific egg production rates, by assuming that those rates are representative for juvenile specific growth rates (Berggreen et al., 1988).

Radiocarbon datings of Upper Quaternary bottom sediments from the Mediterranean Sea

Bottom sediment samples were collected in the Central Mediterranean, Southern Adriatic, Tyrrhenian, Algerian-Provencal, and Alboran basins of the Mediterranean Sea. Fifty-six datings were done for 12 sediment cores. The lowest sedimentation rates during Holocene were found on the abyssal plain of the Algerian-Provencal basin (2.4-4.0 cm/ky). In the Southern Adriatic, Tyrrhenian, and Alboran basins sedimentation rates were somewhat higher (6-12 cm/ky). On slopes of the Southern Adriatic and Tyrrhenian basins during Late Würm glaciation rates of "normal" sedimentation were within the range 11.8-26.8 cm/ky.

Physical/chemical properties and stable oxygen and carbon isotope records of Holocene to late Pleistocene sediments in the Gela Basin, central Mediterranean Sea

The Holocene Twin Slides form the most recent of recurrent mass wasting events along the NE portion of Gela Basin within the Sicily Channel, central Mediterranean Sea. Here, we present new evidence on the morphological evolution and stratigraphic context of this coeval slide complex based on deepdrilled sediment sequences providing a >100 ka paleo-oceanographic record. Both Northern (NTS) and Southern Twin Slide (STS) involve two failure stages, a debris avalanche and a translational slide, but are strongly affected by distinct preconditioning factors linked to the older and buried Father Slide. Core-acoustic correlations suggest that sliding occurred along sub-horizontal weak layers reflecting abrupt physical changes in lithology or mechanical properties. Our results show further that headwall failure predominantly took place along sub-vertical normal faults, partly through reactivation of buried Father Slide headscarps.

Composition of bottom sediments from Mediterranean anoxis basins

Biomass and size structure of planktic infusoria communities were investigated in March 1987 at nine stations on a 370 mile transect across the coastal upwelling zone, the California current, and subtropical waters. Infusoria compose up to 71-92% of total biomass of heterotrophic micro- and nannoplankton; their biomass was 0.6-2.0 g/m**2 in the 0-200 m layer. Distinctive characteristics of taxonomic and size structures were of great diversity of microplanktic Stormbilidiwn forms, comparatively low abundance of tintinnids, and high abundance of nannoplanktic infusoria that accounted for 26-54% of biomass.

Individual dinoflagellate cysts species of surface sediment samples from the Mediterranean Sea

To determine the relationship between the spatial dinoflagellate cyst distribution and oceanic environmental conditions, 34 surface sediments from the Eastern and Western Mediterranean Sea have been investigated for their dinoflagellate cyst content. Multivariate ordination analyses identified sea-surface temperature, chlorophyll-a , nitrate concentration, salinity, and bottom oxygen concentration as the main factors affecting dinoflagellate cyst distribution in the region. Based on the relative abundance data, two associations can be distinguished that can be linked with major oceanographic settings. (1) An offshore eastern Mediterranean regime where surface sediments are characterized by oligotrophic, warm, saline surface water, and high oxygen bottom water concentrations (Impagidinium species, Nematosphaeropsis labyrinthus, Pyxidinopsis reticulata and Operculodinium israelianum). Based on the absolute abundance, temperature is positively related to the cyst accumulation of Operculodinium israelianum. Temperature does not form a causal factor influencing the accumulation rate of the other species in this association. Impagidinium species and Nematosphaeropsis labyrinthus show a positive relationship between cyst accumulation and nitrate availability in the upper waters. (2) Species of association 2 have highest relative abundances in the Western Mediterranean Sea, Strait of Sicily/NW Ionian Sea, and/or the distal ends of the Po/Nile/Rhône River plumes. At these stations, surface waters are characterized by (relative to the other regime) higher productivity associated with lower sea-surface temperature, salinity, and lower bottom water oxygen concentrations (Selenopemphix nephroides, Echinidinium spp., Selenopemphix quanta, Quinquecuspis concreta, Brigantedinium spp. and Lingulodinium machaerophorum). Based on both the absolute and relative abundances, Selenopemphix nephroides is suggested to be a suitable indicator to trace changes in the trophic state of the upper waters. The distribution of Lingulodinium machaerophorum is related to the presence of river-influenced surface waters, notably the Nile River. We suggest that this species might form a suitable marker to trace past variations in river discharge, notably from the Nile.

Ciliates abundance in the eastern Mediterranean Sea in March and April 2008 during SES_GR1

The dataset is based on samples collected in the framework of the project SESAME, in the Ionian, Libyan and Aegean Sea during March- April 2008. For ciliate identification and enumeration, 100-3000 ml samples were left for 24h-4d for sedimentation and then observed under an inverted microscope. Ciliates were counted, distinguished into size-classes and major taxonomic groups and identified down to genus or species level where possible (Pitta et al. 2005).

Phytoplankton responses and associated carbon cycling during shipboard carbonate chemistry manipulation experiments conducted around Northwest European shelf seas

The ongoing oceanic uptake of anthropogenic carbon dioxide (CO2) is significantly altering the carbonate chemistry of seawater, a phenomenon referred to as ocean acidification. Experimental manipulations have been increasingly used to gauge how continued ocean acidification will potentially impact marine ecosystems and their associated biogeochemical cycles in the future; however, results amongst studies, particularly when performed on natural communities, are highly variable, which may reflect community/environment-specific responses or inconsistencies in experimental approach. To investigate the potential for identification of more generic responses and greater experimentally reproducibility, we devised and implemented a series (n = 8) of short-term (2-4 days) multi-level (>=4 conditions) carbonate chemistry/nutrient manipulation experiments on a range of natural microbial communities sampled in Northwest European shelf seas. Carbonate chemistry manipulations and resulting biological responses were found to be highly reproducible within individual experiments and to a lesser extent between geographically separated experiments. Statistically robust reproducible physiological responses of phytoplankton to increasing pCO2, characterised by a suppression of net growth for small-sized cells (<10 µm), were observed in the majority of the experiments, irrespective of natural or manipulated nutrient status. Remaining between-experiment variability was potentially linked to initial community structure and/or other site-specific environmental factors. Analysis of carbon cycling within the experiments revealed the expected increased sensitivity of carbonate chemistry to biological processes at higher pCO2 and hence lower buffer capacity. The results thus emphasise how biogeochemical feedbacks may be altered in the future ocean.