Influence of Organic Enrichment and Spisula subtruncata (da Costa, 1778) on Oxygen and Nutrient Fluxes in Fine Sand Sediments

[EN] The role of labile organic material and macrofaunal activity in benthic respiration and nutrient regeneration have been tested in sublittoral fine sand sediments from the Gulf of Valencia (northwestern Mediterranean Sea). Three experimental setups were made using benthic chambers. One experiment was performed in-situ through the annual cycle in a well-sorted fine sand community. The remaining experiments were carried out with mesocosms under laboratory conditions: one with different concentrations of organic enrichment (mussel meat and concentrated diatoms culture), and the other adding two different densities of the endofaunal bivalve Spisula subtruncata. Biochemical variables in surface sediment and changes in oxygen consumption and nutrient fluxes throughout incubation period were studied in each experiment. In the in situ incubations, dissolved oxygen (DO) fluxes showed a strong correlation with sedimentary biopolymeric fraction of organic carbon. Organic enrichment in the laboratory experiments was responsible for increased benthic respiration. However, sediment response (expressed as DO uptake and dissolved inorganic nitrogen—DIN—release) between oligotrophic and eutrophic conditions was more intense than between eutrophic and hypertrophic conditions. S. subtruncata abundances close to 400 and 850 ind m−2 also intensified benthic metabolism. DO uptake and DIN production in mesocosms with added fauna were between 60 and 75 % and 65–100 % higher than in the control treatment respectively. The results of these three experiments suggest that the macrobenthic community may increase the benthic respiration by roughly a factor of two in these bottoms, where S. subtruncata is one of the dominant species. Both organic enrichment and macrobenthic community in general, and S. subtruncata in particular, did not seem to have a relevant role in P and Si cycles in these sediments.This research was supported by the Conselleria d'Educacio (Generalitat Valenciana). We are very grateful for the valuable comments of anonymous reviewers on previous version of the manuscript.Sospedra, J.; Falco, S.; Morata, T.; Rodilla, M. (2016). Influence of Organic Enrichment and Spisula subtruncata (da Costa, 1778) on Oxygen and Nutrient Fluxes in Fine Sand Sediments. Estuaries and Coasts. doi:10.1007/s12237-016-0174-1SAller, R.C., and J.Y. Aller. 1998. The effect of biogenic irrigation intensity and solute exchange on diagenetic reaction rates in marine sediments. Journal of Marine Research 56: 905–936.Aminot, A., and M. Chaussepied. 1983. Manuel des analyses chimiques en milieu marin. Brest: Centre National pour l’Exploitation des Oceans.Arnosti, C., and M. Holmer. 2003. 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Arctic in Rapid Transition: Priorities for the future of marine and coastal research in the Arctic.

Understanding and responding to the rapidly occurring environmental changes in the Arctic over the past few decades require new approaches in science. This includes improved collaborations within the scientific community but also enhanced dialogue between scientists and societal stakeholders, especially with Arctic communities. As a contribution to the Third International Conference on Arctic Research Planning (ICARPIII), the Arctic in Rapid Transition (ART) network held an international workshop in France, in October 2014, in order to discuss high-priority requirements for future Arctic marine and coastal research from an early-career scientists (ECS) perspective. The discussion encompassed a variety of research fields, including topics of oceanographic conditions, sea-ice monitoring, marine biodiversity, land-ocean interactions, and geological reconstructions, as well as law and governance issues. Participants of the workshop strongly agreed on the need to enhance interdisciplinarity in order to collect comprehensive knowledge about the modern and past Arctic Ocean's geo-ecological dynamics. Such knowledge enables improved predictions of Arctic developments and provides the basis for elaborate decision-making on future actions under plausible environmental and climate scenarios in the high northern latitudes. Priority research sheets resulting from the workshop's discussions were distributed during the ICARPIII meetings in April 2015 in Japan, and are publicly available online

Chemistry of dense clumps near moving Herbig-Haro objects

Localised regions of enhanced emission from HCO+, NH3 and other species near Herbig-Haro objects (HHOs) have been interpreted as arising in a photochemistry stimulated by the HHO radiation on high density quiescent clumps in molecular clouds. Static models of this process have been successful in accounting for the variety of molecular species arising ahead of the jet; however recent observations show that the enhanced molecular emission is widespread along the jet as well as ahead. Hence, a realistic model must take into account the movement of the radiation field past the clump. It was previously unclear as to whether the short interaction time between the clump and the HHO in a moving source model would allow molecules such as HCO+ to reach high enough levels, and to survive for long enough to be observed. In this work we model a moving radiation source that approaches and passes a clump. The chemical picture is qualitatively unchanged by the addition of the moving source, strengthening the idea that enhancements are due to evaporation of molecules from dust grains. In addition, in the case of several molecules, the enhanced emission regions are longer-lived. Some photochemically-induced species, including methanol, are expected to maintain high abundances for ~10,000 years.Comment: 7 pages, 3 figure

Arctic Oceanography - Oceanography: Atmosphere-Ocean Exchange, Biogeochemistry & Physics

The Arctic Ocean is, on average, the shallowest of Earth’s oceans. Its vast continental shelf areas, which account for approximately half of the Arctic Ocean’s total area, are heavily influenced by the surrounding land masses through river run-off and coastal erosion. As a main area of deep water formation, the Arctic is one of the main «engines» of global ocean circulation, due to large freshwater inputs, it is also strongly stratified. The Arctic Ocean’s complex oceanographic configuration is tightly linked to the atmosphere, the land, and the cryosphere. The physical dynamics not only drive important climate and global circulation patterns, but also control biogeochemical cycles and ecosystem dynamics. Current changes in Arctic sea-ice thickness and distribution, air and water temperatures, and water column stability are resulting in measurable shifts in the properties and functioning of the ocean and its ecosystems. The Arctic Ocean is forecast to shift to a seasonally ice-free ocean resulting in changes to physical, chemical, and biological processes. These include the exchange of gases across the atmosphere-ocean interface, the wind-driven ciruclation and mixing regimes, light and nutrient availability for primary production, food web dynamics, and export of material to the deep ocean. In anticipation of these changes, extending our knowledge of the present Arctic oceanography and these complex changes has never been more urgent

Algunos efectos metabólicos de la sustitución de proteínas por grasa en la dieta para truchas

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For this purpose, the taxonomic composition of the micro-phytoplankton communities at 32 fixed stations was determined in four sampling campaigns from summer 2010 to spring 2011. The results indicate that nutrient inputs mainly from the Serpis river and channels that drain the Safor Wetland determine the composition and abundance of the phytoplankton community, and that several key environmental factors such as water temperature, radiation, nutrients, and the molar ratios of nutrients influence seasonal phytoplankton assemblages. However, the discharge of effluent from a sewage treatment plant through the submarine outfall did not appear to have a significant impact on the phytoplankton community. The phytoplankton community comprised two main groups: diatoms and dinoflagellates and a total of 108 taxa were identified. The diatom population primarily flourished in autumn and winter whereas in spring, dinoflagellate bloom occurred with high radiation, very low DIP and high DIN:DIP and low DSi:DIN molar ratios. In this paper we discuss the possible rationale for these nutrient changes. Furthermore, potentially blooming species were detected in the Gandia harbour and in the mouth of the Serpis river at Venecia Beach.[ES] La variabilidad estacional de la comunidad de fitoplancton de las aguas superficiales de la zona costera de Gandía en el sur del Golfo de Valencia (Mediterráneo occidental) fue examinada, teniendo en cuenta su relación con diferentes variables físicas y químicas (p.e. salinidad, nutrientes, oxígeno disuelto, temperatura, etc.). En esta pequeña área se dan la mayoría de las entradas de nutrientes, tanto puntuales como difusas, que afectan las áreas costeras: descargas de aguas residuales mediante emisarios submarinos, aportes fluviales y descargas de aguas subterráneas procedentes de acuíferos costeros. Además, los canales superficiales que drenan el humedal de La Safor, cuyo uso fundamental es la agricultura, vierten en las aguas confinadas del puerto. El objetivo principal de este estudio fue observar las variaciones de los grupos de fitoplancton como respuesta a las variaciones ambientales en diferentes estaciones del año, y determinar que especies pueden ser utilizadas como indicadores de presión antrópica. Para ello, se determinó la composición taxonómica de la comunidad de micro-fitoplancton en 32 puntos de muestreo fijos en cuatro campañas de muestreo, desde verano de 2010 hasta primavera de 2011. Los resultados muestran que la entrada de nutrientes, principalmente a través del Río Serpis y los canales que drenan el humedal, determinan la composición y abundancia de la comunidad de fitoplancton. Además diversos factores ambientales clave como temperatura del agua, radiación, nutrientes, así como las relaciones entre nutrientes influyen en las diferentes asociaciones de fitoplancton observadas en cada estación. Por otro lado, la descarga del efluente procedente de la depuradora de aguas residuales no tuvo un impacto significativo sobre la comunidad de fitoplancton. La comunidad de fitoplancton estuvo formada principalmente por dos grupos: diatomeas y dinoflagelados. Se identificaron un total de 108 taxones. Las diatomeas proliferaron principalmente en otoño e invierno. Los dinoflagelados proliferaron en primavera, bajo condiciones de elevada radiación, baja concentración de DIP, razones DIN:DIP elevadas y razones DSi:DIN bajas. En este documento se discute la justificación de los cambios en la concentración de nutrientes. Además, se detectaron especies potencialmente nocivas en el Puerto de Gandía y en la desembocadura del río Serpis, en la playa de Venecia.Financial support for this research was provided by Ministry of Education, Culture and Sport, Government of Spain, through the Training Program for University Teachers (FPU). We would like to express our deepest thanks to Margarita Fernández and Vanessa Castan of IRTA (Research Institute of Technology, food and Agriculture).Gadea, I.; Rodilla, M.; Sospedra, J.; Falco, S.; Morata, T. (2013). Seasonal dynamics of the phytoplankton community in the Gandia coastal area, southern Gulf of Valencia. Thalassas. Revista de Ciencias del Mar. 29(1):35-58. http://hdl.handle.net/10251/46133S355829

Systematic Molecular Differentiation in Starless Cores

(Abridged) We present evidence that low-mass starless cores, the simplest units of star formation, are systematically differentiated in their chemical composition. Molecules including CO and CS almost vanish near the core centers, where the abundance decreases by one or two orders of magnitude. At the same time, N2H+ has a constant abundance, and the fraction of NH3 increases toward the core center. Our conclusions are based on a study of 5 mostly-round starless cores (L1498, L1495, L1400K, L1517B, and L1544), which we have mappedin C18O(1-0), C17O(1-0), CS(2-1), C34S(2-1), N2H+(1-0), NH3(1,1) and (2,2), and the 1.2 mm continuum. For each core we have built a model that fits simultaneously the radial profile of all observed emission and the central spectrum for the molecular lines. The observed abundance drops of CO and CS are naturally explained by the depletion of these molecules onto dust grains at densities of 2-6 10^4 cm-3. N2H+ seems unaffected by this process up to densities of several 10^5, while the NH3 abundance may be enhanced by reactions triggered by the disappearance of CO from the gas phase. With the help of our models, we show that chemical differentiation automatically explains the discrepancy between the sizes of CS and NH3 maps, a problem which has remained unexplained for more than a decade. Our models, in addition, show that a combination of radiative transfer effects can give rise to the previously observed discrepancy in the linewidth of these two tracers. Although this discrepancy has been traditionally interpreted as resulting from a systematic increase of the turbulent linewidth with radius, our models show that it can arise in conditions of constant gas turbulence.Comment: 25 pages, 9 figures, accepted by Ap

Are Neurotrophin Genes Involved in the Pathophysiology of Gambling Disorder?

N/