A NEW SPECIES OF CHILOMYCTERUS FROM NEW GUINEA.

abstract not availabl

ON A COLLECYTION OF FRESHWATER FISHES OF THE ISLAND OF BILLITON

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Calcite production by Coccolithophores in the South East Pacific Ocean: from desert to jungle

International audienceBIOSOPE cruise achieved an oceanographic transect from the Marquise Islands to the Peru-Chili upwelling (PCU) via the centre of the South Pacific Gyre (SPG). Water samples from 6 depths in the euphotic zone were collected at 20 stations. The concentrations of suspended calcite particles, coccolithophores cells and detached coccoliths were estimated together with size and weight using an automatic polarizing microscope, a digital camera, and a collection of softwares performing morphometry and pattern recognition. Some of these softwares are new and described here for the first time. The coccolithophores standing stocks are usually low and reach maxima west of the PCU. The coccoliths of Emiliania huxleyi, Gephyrocapsa spp. and Crenalithus spp. (Order Isochrysidales) represent 50% of all the suspended calcite particles detected in the size range 0.1–46 µm (21% of PIC in term of the calcite weight). The latter species are found to grow preferentially in the Chlorophyll maximum zone. In the SPG their maximum concentrations was found to occur between 150 and 200 m, which is very deep for these taxa. The weight and size of coccoliths and coccospheres are correlated. Large and heavy coccoliths and coccospheres are found in the regions with relative higher fertility in the Marquises Island and in the PCU. Small and light coccoliths and coccospheres are found west of the PCU. This distribution may correspond to that of the concentration of calcium and carbonate ions

The Role of ocean acidification in Emiliania huxleyi coccolith thinning in the Mediterranean Sea

Ocean acidification is a result of the uptake of anthropogenic CO₂ from the atmosphere into the ocean and has been identified as a major environmental and economic threat. The release of several thousands of petagrams of carbon over a few hundred years will have an overwhelming effect on surface ocean carbon reservoirs. The recorded and anticipated changes in seawater carbonate chemistry will presumably affect global oceanic carbonate production. Coccolithophores as the primary calcifying phytoplankton group, and especially Emiliania huxleyi as the most abundant species have shown a reduction of calcification at increased CO₂ concentrations for the majority of strains tested in culture experiments. A reduction of calcification is associated with a decrease in coccolith weight. However, the effect in monoclonal cultures is relatively small compared to the strong variability displayed in natural E. huxleyi communities, as these are a mix of genetically and sometimes morphologically distinct types. Average coccolith weight is likely influenced by the variability in seawater carbonate chemistry in different parts of the world's oceans and on glacial/interglacial time scales due to both physiological effects and morphotype selectivity. An effect of the ongoing ocean acidification on E. huxleyi calcification has so far not been documented in situ. Here, we analyze E. huxleyi coccolith weight from the NW Mediterranean Sea in a 12-year sediment trap series, and surface sediment and sediment core samples using an automated recognition and analyzing software. Our findings clearly show (1) a continuous decrease in the average coccolith weight of E. huxleyi from 1993 to 2005, reaching levels below pre-industrial (Holocene) and industrial (20th century) values recorded in the sedimentary record and (2) seasonal variability in coccolith weight that is linked to the coccolithophore productivity. The observed long-term decrease in coccolith weight is most likely a result of the changes in the surface ocean carbonate system. Our results provide the first indications of an in situ impact of ocean acidification on coccolithophore weight in a natural E. huxleyi population, even in the highly alkaline Mediterranean Sea

Influence of stoichiometry and structure on the optical properties of AlNxOy films

The AlNxOy system offers the possibility to obtain a wide range of responses, by tailoring the properties between Al, AlN and Al2O3, opening a significant number of possible applications. The aim of this work is to correlate the optical properties of AlNxOy thin films with their composition and structural features, taking as reference the binary systems AlNx and AlOy. In the AlNx system, the increase of the nitrogen content induced a wide variation in the optical properties, ranging from the typical profile of a polycrystalline Al-type film towards nearly constant reflectance values as low as 5%, as well as a smooth increase in samples transparency as the ratio N/Al approached unit. In the case of the AlOy system, the reflectance also decreased as the oxygen content increased, however the transition to transparent films (Al2O3-like) was more abrupt. The ternary system AlNxOy, revealed optical responses that ranged from a typical profile of a polycrystalline Al-type film, towards low and constant reflectance values in a wide range of x and y coefficients, ending up as semi-transparent when Al2O3-like films were formed. The unusual low optical reflectance of some films reveals some potential applications in solar power systems and sensors.This research is sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade, by national funds through FCT,, under the projects PTDC/CTMNAN/ 112574/2009 and PEST-C-FIS/UI607/2011–2012, and Programa Pessoa 2010/2011—Cooperação Portugal/França, Proc. no 441.00, Project ‘COLOURCLUSTER’. J Borges also acknowledges FCT financial support under PhD grant no SFRH/BD/47118/200

Eccentricity forcing on tropical ocean seasonality

The amount of radiative energy received at the Earth's surface depends on two factors: Earth–Sun distance and sunlight angle. Because of the former, high-eccentricity cycles can induce the appearance of seasons in the tropical ocean. In this paper, we use the Earth system model IPSL-CM5A2 to investigate the response of the low-latitude ocean to variations in Earth's orbit eccentricity. Sea surface temperature (SST) and primary production (PP) were simulated under six precession configurations at high eccentricity and two configurations at low eccentricity, representing extreme configurations observed over the past 1 million years. Results show that high eccentricity leads to increased seasonality in low-latitude mean SST, with an annual thermal amplitude of approximately 2.2 °C (vs. 0.5 °C at low eccentricity). Low-latitude mean PP, which already exhibits inherent seasonality under low-eccentricity conditions, sees its seasonality largely increased under high eccentricity. As a consequence, we show that on long timescales the intensity of SST seasonality exhibits only the eccentricity frequency, whereas that of PP additionally follows precession dynamics. Furthermore, the seasonal variations in both SST and PP at high eccentricities are influenced by the annual placement of the perihelion with its direct impact of radiative energy received in tropical regions. This leads to a gradual and consistent transition of seasons within the calendar. We introduce the concept of “eccentriseasons”, referring to distinct annual thermal differences observed in tropical oceans under high-eccentricity conditions, which shift gradually throughout the calendar year. These findings have implications for understanding low-latitude climate phenomena such as the El Niño–Southern Oscillation (ENSO) and monsoons in the past.</p

Calcification response of a key phytoplankton family to millennial-scale environmental change

Coccolithophores are single-celled photosynthesizing marine algae, responsible for half of the calcification in the surface ocean, and exert a strong influence on the distribution of carbon among global reservoirs, and thus Earth’s climate. Calcification in the surface ocean decreases the buffering capacity of seawater for CO2, whilst photosynthetic carbon fixation has the opposite effect. Experiments in culture have suggested that coccolithophore calcification decreases under high CO2 concentrations ([CO2(aq)]) constituting a negative feedback. However, the extent to which these results are representative of natural populations, and of the response over more than a few hundred generations is unclear. Here we describe and apply a novel rationale for size-normalizing the mass of the calcite plates produced by the most abundant family of coccolithophores, the Noëlaerhabdaceae. On average, ancient populations subjected to coupled gradual increases in [CO2(aq)] and temperature over a few million generations in a natural environment become relatively more highly calcified, implying a positive climatic feedback. We hypothesize that this is the result of selection manifest in natural populations over millennial timescales, so has necessarily eluded laboratory experiments

Electrical properties of AlNxOy thin films prepared by reactive magnetron sputtering

Direct current magnetron sputtering was used to produce AlNxOy thin films, using an aluminum target, argon and a mixture of N2+O2 (17:3) as reactive gases. The partial pressure of the reactive gas mixture was increased, maintaining the discharge current constant. Within the two identified regimes of the target (metallic and compound), four different tendencies for the deposition rate were found and a morphological evolution from columnar towards cauliflower-type, ending up as dense and featureless-type films. The structure was found to be Al-type (face centered cubic) and the structural characterization carried out by X-ray 2 diffraction and transmission electron microscopy suggested the formation of an aluminumbased polycrystalline phase dispersed in an amorphous aluminum oxide/nitride (or oxynitride) matrix. This type of structure, composition, morphology and grain size, were found to be strongly correlated with the electrical response of the films, which showed a gradual transition between metallic-like responses towards semiconducting and even insulating-type behaviors. A group of films with high aluminum content revealed a sharp decrease of the temperature coefficient of resistance (TCR) as the concentration ratio of non-metallic/aluminum atomic ratio increased. Another group of samples, where the non-metallic content became more important, revealed a smooth transition between positive and negative values of TCR. In order to test whether the oxynitride films have a unique behavior or simply a transition between the typical responses of aluminum and of those of the correspondent nitride and oxide, the electrical properties of the ternary oxynitride system were compared with AlNx and AlOy systems, prepared in similar conditions.This research is sponsored by FEDER funds through the program COMPETE-Programa Operacional Factores de Competitividade, by the national funds through FCT-Fundação para a Ciência e a Tecnologia, under the project PTDC/CTM-NAN/112574/2009 and Programa Pessoa 2010/2011 Cooperação Portugal/França, Proc.º 441.00, Project“COLOURCLUSTER”. J. Borges also acknowledges FCT financial support under PhD grant no. SFRH/BD/47118/2008

Incentives for smoking cessation during pregnancy:an ethical framework

INTRODUCTION: Smoking during pregnancy increases the risk of morbidity and mortality of the mother and child. The inability of the unborn child to protect itself, raises the social and academic responsibility to protect the child from the harmful effects of smoking. Interventions including rewards ('incentives') for lifestyle changes are an upcoming trend and can encourage women to quit smoking. However, these incentives can, as we will argue, also have negative consequences, for example the restriction of personal autonomy and encouragement of smoking to become eligible for participation. To prevent these negative consequences, we developed an ethical framework that enables to assess and address unwanted consequences of incentive-based interventions whereby moral permissibility can be evaluated. METHODS: The possible adverse consequences of incentives were identified through an extensive literature search. Subsequently, we developed ethical criteria to identify these consequences based on the biomedical ethical principles of Beauchamp and Childress. RESULTS: Our framework consists of twelve criteria. These criteria concern (i) effectiveness, (ii) support of a healthy lifestyle, (iii) motivational for the target population, (iv) stimulating unhealthy behaviour, (v) negative attitudes, (vi) personal autonomy, (vii) intrinsic motivation, (viii) privacy, (ix) fairness, (x) allocation of incentives, (xi) cost-effectiveness, and (xii) health inequity. Based on these criteria, the moral permissibility of potential interventions can be evaluated. CONCLUSION: Incentives for smoking cessation are a response to the responsibility to protect the unborn child. But these interventions might have possible adverse effects. This ethical framework aims to identify and address ethical pitfalls in order to avoid these adverse effects

Technical note: A comparison of methods for estimating coccolith mass

The fossil record of coccolithophores dates back approximately 225 million years, and the production of their calcite platelets (coccoliths) contributes to the global carbon cycle over short and geological timescales. Variations in coccolithophore parameters (e.g. community composition, morphology, size and coccolith mass) are a key factor for ocean biogeochemical dynamics (e.g. biological carbon pump) and have been used as a palaeoproxy to understand past oceanographic conditions. Coccolith mass has been frequently estimated with different methods with electron microscopy being the most applied. Here, we compared the electron microscopy (EM) method with the Coulter multisizer (CM) (i.e. electric field disturbance) and bidirectional circular polarization (BCP) methods to estimate coccolith masses (pg CaCO3) in controlled laboratory experiments with two ecotypes of Emiliania huxleyi. Average coccolith mass estimates were in good agreement with literature data. However, mass estimates from the CM were slightly overestimated compared to EM and BCP estimates, and a correction factor (cf=0.8) is suggested to compensate for this discrepancy. The relative change in coccolith mass triggered by morphotype-specific structures and environmental parameters (i.e. seawater carbonate chemistry) was suitably captured by each of the three techniques.</p