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About one-third of the carbon dioxide (CO2) released into the atmosphere as a result of human activity has been absorbed by the oceans, where it partitions into the constituent ions of carbonic acid. This leads to ocean acidification, one of the major threats to marine ecosystems and particularly to calcifying organisms such as corals, foraminifera and coccolithophores. Coccolithophores are abundant phytoplankton that are responsible for a large part of modern oceanic carbonate production. Culture experiments investigating the physiological response of coccolithophore calcification to increased CO2 have yielded contradictory results between and even within species. Here we quantified the calcite mass of dominant coccolithophores in the present ocean and over the past forty thousand years, and found a marked pattern of decreasing calcification with increasing partial pressure of CO2 and concomitant decreasing concentrations of CO32?. Our analyses revealed that differentially calcified species and morphotypes are distributed in the ocean according to carbonate chemistry. A substantial impact on the marine carbon cycle might be expected upon extrapolation of this correlation to predicted ocean acidification in the future. However, our discovery of a heavily calcified Emiliania huxleyi morphotype in modern waters with low pH highlights the complexity of assemblage-level responses to environmental forcing factors. [ABSTRACT FROM AUTHOR]

Abstract: A series of new iron(II) complexes bearing tridentate pyrazine-bis(2,6-arylimino) ligands where the aryl groups are 1-naphthyl, 2,6-dimethylphenyl, and 2,6-diisopropylphenyl have been used as ethylene polymerization catalysts after activation with alkylaluminiums. The new complexes display a lesser catalytic activity than those bearing the corresponding pyridine-bis(2,6-arylimino) ligands. Varying the steric bulkiness of the aromatic groups in the tridentate ligands and the polymerization conditions affects the catalytic productivity. [Copyright &y& Elsevier]

Abstract: The synthesis of a new series of 2,6-bis(imino)pyrazinyl ligands, [Arh name="dbnd" />Cyph name="sbnd" />Ch name="sbnd" />Ar] where the aryl groups Ar=naphtyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, and their iron(II) complexes is described starting from monoacetylpyrazine. [Copyright &y& Elsevier]

Syste`me de Reconnaissance Automatique de Coccolithes (SYRACO) is a tool for automatic recognition of coccoliths by neural networks. Previous versions of this tool were able to identify individual species of coccoliths with a high reliability, but failed in that many coccoliths were overlooked. SYRACO was able to identify only about half the coccoliths present in a field of view. We have now developed a new type of Neural Network, which includes a dynamic view of the object analysed. We have added parallel neural networks, which perform five types of simple image transformation to the general back-propagation neural network. This new dynamic version of SYRACO is able to identify individual coccoliths even more reliably at the same time as it is able to recognize almost all coccoliths present in a field of view. The only remaining problem concerns the inclusion of objects that are not coccoliths. This problem can be solved partly by performing a secondary SYRACO analysis of output images. The performance of the current system is demonstrated using the study of 21 EUMELI sediment trap samples. [Copyright &y& Elsevier]

Coccolithophorid assemblages and micro-charcoal content were analysed in giant piston core MD97-2141 recovered in the Sulu Sea (Philippines). These proxies help to reconstruct respectively the dynamics of the oceanic primary production (PP) and biomass burning in that area. PP in the Sulu Sea intensifies during the East Asian winter monsoon (EAWM) and therefore PP constitutes a proxy for EAWM dynamics. Most of the precipitation in the Sulu Sea region occurs during the East Asian summer monsoon (EASM). Because the intensity of biomass burning is related to dryness of the surrounding area, the sedimentary micro-charcoal content can be used as an inverse proxy for EASM intensity. Our results show that the EAWM intensifies during glacial times in agreement with previous studies. Precessional forcing appears to act directly on EAWN because of the early response of PP in that frequency band. The micro-charcoal record exhibits complex dynamics, which we attribute to the competing influence of the long-term El Nin˜o Southern Oscillation (ENSO)-like forcing and the glacial/interglacial cycle on EASM. These influences create an unusual frequency spectrum with power around 30 kyr and 19 kyr attributed to the non-linear response to the 100-kyr cycle (glacial) and the 23-kyr (ENSO) cycle. A factor of two increase in the amplitude of the micro-charcoal variability between 51 and 10 ka BP could correspond to Homo sapiens biomass burning in the style of the fire-stick farming of the Australian Aborigines. We also find, on precession cycles, an opposite phase between EASM and EAWM records and an advance of −δ18O and δ18O respectively by 2000 yr. [Copyright &y& Elsevier]

When micron-sized particles are suspended into the dense brine waters of a deep hypersaline basin, in the absence of biological packaging, their settling velocities should be greatly attenuated. We observed this phenomenon in the anoxic brine water of the Urania Basin in the eastern Mediterranean. We found that the deepest part of this basin is filled with a high-density, about 110 m thick, homogenous fluid mud layer mainly containing microfossils of coccoliths and nannoplankton of Pleistocene and Pliocene age that float in a hot methane-laden brine overlaid by a 'clear' brine. The top of the fluid mud forms a secondary 'suspended seafloor' that has been stable for at least the last two decades since the discovery of the basin. The geochemical characteristics of the fluid mud (e.g. lower salinity than the clear brine, methane-rich) point to a deep source for the fluids, while the age of the microfossils suggests that the floating biogenic particles came from shallower, post-Messinian pelagic deposits such as those exposed along the walls and the rim of the Urania Basin. We hypothesize that catastrophic gravity failures and mass mobilization of the post-Messinian sedimentary layers triggered by earthquake activity are one of the main sources of the sediment in the fluid mud. Because of both, the dense brine fluids, the continuous mixing by thermal convection and the very fine grained nature of the particles, the re-mobilized sediments have never settled, and stay suspended as if they were frozen in time. The prolonged residence time of the supersaturated fluids and the associated microbial activity have also fostered the precipitation of the authigenic gypsum crystals and micron-sized authigenic carbonates that occur mixed with the fluid mud sediments. [ABSTRACT FROM AUTHOR]

The geochemistry of Upper Quaternary organic-rich (C 3.7-10.0%) sediments recovered by the 40-m-long Core MD02-2508 from the upper continental slope of Baja California is compared to the chemical composition of sedimentary rocks from the Miocene Monterey Formation, California. It is ascertained that concentrations of most macroelements (Al, Ti, Mg, K, Fe, M, S, C) and many microelements, including chalcophiles Ag, As, Mo, Sb, Se, Zn, along with some others (U, Co, Ni, Y, and REE) are nearly equal in both types of sediments. In addition, concentrations of most microelements in both types of sediments are close, to the average values common for the worldwide carbonaceous black shales irrespective of their lithology and age, indicating a stable influence of organic matter on their concentration during sedimentation and early digenesis. [ABSTRACT FROM AUTHOR]

Core MD02-2508 retrieved from the plateau of the continental slope off Baja California recovered a 40-m-thick section of sapropel (up to 15% Corg), calcareous clay, and diatom ooze with the age of 120 ka at the core bottom. The section is subdivided into three units: Unit I (Holocene) consists of the laminated sapropel; Unit II comprising oxygen isotope stages (MIS) 2, 3, and 4 is represented by homogeneous calcareous clay with interbeds of slightly siliceous sapropelic mud; and Unit III (MIS-5) is composed of laminated sapropelic diatom ooze. Laminated intervals are characterized by the intercalation of two lamina types: (1) dark-colored organic-rich laminae containing multi-species “oceanic” diatom assemblages, as well as radiolarians, coccoliths, planktonic and benthic foraminifera; (2) lighter-colored laminae consisting of diatom ooze with the neritic colonial diatom assemblages commonly composed of one to three species of a single genera. The dark laminae are assumed to be generated within a high productivity zone over the slope, whereas light ones likely represent diatom mats produced by short-term boisterous phytoplankton blooms, possibly in the coastal upwelling. [ABSTRACT FROM AUTHOR]

Abstract: Paleoenvironmental records in Europe describing paleofires extending back to the Last Interglacial have so far been unavailable. Here, we present paleofire results from the combined petrographic and automated image analysis of microcharcoal particles preserved in marine core MD95-2042 retrieved off southwestern Iberia and covering the last climatic cycle. The variability of microcharcoal concentrations reveals that the variability of fire emissions is mainly imprinted by the 23000yr precessional cycle. A focus on the Last Glacial Period further shows that paleofires follow the variability of Dansgaard–Oeschger oscillation and Heinrich events and, therefore, parallel the variability of atmospheric temperatures over Greenland detected in ice cores. There is no evidence for fire increase related to human activity. The variability of fire emission by-products for the Last Glacial Period is interpreted in terms of changes in biomass availability. Low fire activity is associated with periods of drought which saw the development of semi-desert vegetation that characterised stadial periods. Fire activity increased during wetter interstadials, related to the development of open Mediterranean forests with more woody fuel availability. [Copyright &y& Elsevier]

The inland fisheries sector is central for subsistence in many regions worldwide. The exploitation of fish resources is expected to increase along with the growing human population, with underlying conservation issues in regions with high biodiversity value. The small fishery of the Maroni River, French Guiana, is a hotspot of biodiversity and endemism where resource depletion is suspected. We surveyed 754 boat landings in seven villages located in the upper half of the watershed, representing > 6300 fish during the study period (November 2013 - September 2014). Fishers used canoes with outboard engines almost exclusively (75 %) and fished within 32 km of their villages. Most fish were caught in trammel nets (81 %); the 20 most-landed species represented more than 87 % of catches. Depending on the village, daily catches and biomass averaged 6–14 fish and 1.7−13 kg per boat landing, respectively. Seven control sites located outside of the fishing grounds were fished to identify potential differences in catch per unit effort and fish size. Per 100 m2 of trammel net, mean catches ranged from 4 to 13 and 8–29 fish in the villages and control sites, respectively, while fish biomass ranged from 0.9 to 4 and 3.2−7 kg in villages and control sites, respectively. For all species combined, fish caught at control sites were bigger than those landed in villages. This difference was significant for nine of the most-landed species. Differences in fishing techniques and fish catches between villages illustrated the gradual disappearance of the ancestral subsistence fishing. Our results support indications that the fish community in the upper Maroni River is harvested intensively, address the issue of sustainability of the fishery there, and call attention to the need to conserve the river's remarkable biodiversity. [ABSTRACT FROM AUTHOR]

Coccolithophores are calcifying marine phytoplankton of the class Prymnesiophyceae. They are considered to play an import role in the global carbon cycle through the production and export of organic carbon and calcite. We have compiled observations of global coccolithophore abundance from several existing databases as well as individual contributions of published and unpublished datasets. We make conservative estimates of carbon biomass using standardised conversion methods and provide estimates of uncertainty associated with these values. The quality-controlled database contains 57 321 individual observations at various taxonomic levels. This corresponds to 11 503 observations of total coccolithophore abundance and biomass. The data span a time period of 1929-2008, with observations from all ocean basins and all seasons, and at depths ranging from the surface to 500 m. Highest biomass values are reported in the North Atlantic, with a maximum of 127.2 μgCL-1. Lower values are reported for the Pacific (maximum of 20.0 μgCL-1) and Indian Ocean (up to 45.2 μgCL-1). Maximum biomass values show peaks around 60° N and between 40 and 20° S, with declines towards both the equator and the poles. Biomass estimates between the equator and 40° N are below 5 μgCL-1. Biomass values show a clear seasonal cycle in the Northern Hemisphere, reaching a maximum in the summer months (June-July). In the Southern Hemisphere the seasonal cycle is less evident, possibly due to a greater proportion of low-latitude data. The original and gridded datasets can be downloaded from Pangaea doi:10.1594/PANGAEA.785092). [ABSTRACT FROM AUTHOR]

The article presents a study which estimates the carbon biomass distributions of the global marine plankton know as coccolithophores. The study used remote sensing approaches, a quality control procedure, and statistical analyses. Results show that biomass distributions in North Atlantic were the highest biomass values, and all planktons were seen across the latitudes of the Northern Hemisphere.

Abstract: The mismatch between the 100 and 400 k.y. components of Pleistocene climate and the relative power of those terms from the eccentricity of the Earth''s orbit remains a challenge to the Milankovitch hypothesis. Coccolithophores have the potential to respond to parameters of orbital forcing other than insolation, and, as a critical component of the ocean carbon cycle, can act to modify the climate response. The first direct comparison of coccolith fraction Sr/Ca, alkenone abundance and automated coccolithophore counts, shows that CF Sr/Ca is largely driven by changing production of bloom species, with unusually high Sr/Ca ratios. The periods of high CF Sr/Ca and high bloom production mark periods of high global coccolithophore production, which correlate inversely with the low amplitude 100 and higher amplitude 400 k.y. eccentricity orbital frequency. ∼400 k.y. cycles of coccolithophore bloom production correspond to periods of enhanced carbonate accumulation in some parts of the ocean, deep ocean dissolution in others, positive shifts in global ocean δ13C, and acmes of Gephyrocapsa caribbeanica and Emiliania huxleyi. The link between production of coccolithophore blooms and eccentricity may be due to orbital control of silica leakage from the Southern Ocean, to the orbitally defined inverse correlation between insolation and growing season length and the asymptotic growth response to these parameters, or to changes in nutrient input from weathering. During the Pleistocene, the eccentricity induced coccolithophore acmes have no apparent influence on atmospheric carbon dioxide (pCO2) due to the shift towards small bloom coccolithophores, or to coupling with increased diatom productivity, or the ballast effect of the calcium carbonate rain, such that Pleistocene climate has no significant variance at the largest amplitude eccentricity forcing of 400 k.y. Coccolithophores and their influence on the carbon cycle may act as a filter between the incident orbital forcing and resultant climate. [Copyright &y& Elsevier]

Abstract: A new piston core from Santa Barbara Basin, California provides evidence of the timing, magnitude, and character of deglaciation, including evidence of warming prior to Termination IA. IMAGES Site MD02-2503 (570m water depth) consists of intermittently laminated hemipelagic sediments extending to Interstadial (D/O) event 6 (∼34ka), that accumulated at ∼135cm/ka. During the deglacial episode (16.75–10ka), δ 18O values decreased by 3.2‰ in the planktonic species Globigerina bulloides, indicating a total warming of 8–9°C recorded by surface-dwelling foraminifera (inferred by removing the 1‰ influence of ice volume change). Similarly, benthic species (Bolivina argentea and Uvigerina peregrina) record a 1.65‰δ 18O decrease across the deglacial, interpreted as a 2–3°C warming at upper intermediate depths. δ 18O values of both planktonic and benthics indicate that surface and intermediate waters began to warm ∼2ka prior to Termination IA, beginning at ∼16.5ka. Intermediate water warming exhibits similar structure and synchronous timing with surface waters. These findings are consistent with a growing number of records from around the globe that exhibit pre-Bølling warming prior to Termination IA, and extends the record of such processes to the northern Pacific. [Copyright &y& Elsevier]

Marine hydrocarbon seepage emits oil and gas, including methane (≈30 Tg of CH4 per year), to the ocean and atmosphere. Sediments from the California margin contain preserved tar, primarily formed through hydrocarbon weathering at the sea surface. We present a record of variation in the abundance of tar in sediments for the past 32,000 years, providing evidence for increases in hydrocarbon emissions before and during Termination IA [16,000 years ago (16 ka) to 14 ka] and again over Termination IB (11–10 ka). Our study provides direct evidence for increased hydrocarbon seepage associated with deglacial warming through tar abundance in marine sediments, independent of previous geochemical proxies. Climate-sensitive gas hydrates may modulate thermogenic hydrocarbon seepage during deglaciation. [ABSTRACT FROM AUTHOR]

New records of past sea surface temperatures (SSTs) were derived in the 30–50 kyr B.P. time interval from a core located at 45°S in the Southern Indian Ocean, MD94-103. To investigate the climatic phasing between the Southern Indian Ocean, the Greenland and the Antarctic ice, the magnetic signal of core MD94-103 was synchronized at better than millennial accuracy in the vicinity of the Laschamp geomagnetic to a reference record, NAPIS-75, already placed on the GISP2 age model. Coccolithophorid and diatom species abundances both point to a cooling of surface waters during H4. Specific diatoms also indicate lower salinity waters during the same time interval. These observations do not support the idea that the South hemisphere warmed 1.5–2 kyr before the North hemisphere (Nature 394 (1998) 739). Rather, alkenone-derived SSTs suggest that cold conditions have characterized the surface waters in the south latitudes during H4 and H5, and that temperature at evaporation sites contributed to the isotopic events A1 and A2 visible in the isotopic records of central Antarctica (Earth Planet. Sci. Lett. 177 (2000) 219). SSTs obtained from foraminifera assemblages depict somewhat different temperature patterns, possibly indicative of water stratification. [Copyright &y& Elsevier]

Presents a study which obtained a downward particle flux with moored sediment traps at several depths of the water column in regions characterized by production levels of the North Atlantic Ocean. Methodology; Results; Discussion.