Horizontal and Vertical Distributions of Transparent Exopolymer Particles (TEP) in the NW Mediterranean Sea Are Linked to Chlorophyll a and O2 Variability

12 pages, 6 figures, 3 tables, supplementary material http://journal.frontiersin.org/article/10.3389/fmicb.2016.02159/full#supplementary-materialTransparent Exopolymer Particles (TEP) are relevant in particle and carbon fluxes in the ocean, and have economic impact in the desalination industry affecting reverse osmosis membrane fouling. However, general models of their occurrence and dynamics are not yet possible because of the poorly known co-variations with other physical and biological variables. Here, we describe TEP distributions in the NW Mediterranean Sea during late spring 2012, along perpendicular and parallel transects to the Catalan coast. The stations in the parallel transect were sampled at the surface, while the stations in the perpendicular transect were sampled from the surface to the bathypelagic, including the bottom nepheloid layers. We also followed the short-term TEP dynamics along a 2-day cycle in offshore waters. TEP concentrations in the area ranged from 4.9 to 122.8 and averaged 31.4 ± 12.0 μg XG eq L−1. The distribution of TEP measured in transects parallel to the Catalan Coast correlated those of chlorophyll a (Chla) in May but not in June, when higher TEP-values with respect to Chla were observed. TEP horizontal variability in epipelagic waters from the coast to the open sea also correlated to that of Chla, O2 (that we interpret as a proxy of primary production) and bacterial production (BP). In contrast, the TEP vertical distributions in epipelagic waters were uncoupled from those of Chla, as TEP maxima were located above the deep chlorophyll maxima. The vertical distribution of TEP in the epipelagic zone was correlated with O2 and BP, suggesting combined phytoplankton (through primary production) and bacterial (through carbon reprocessing) TEP sources. However, no clear temporal patterns arose during the 2-day cycle. In meso- and bathypelagic waters, where phytoplanktonic sources are minor, TEP concentrations (10.1 ± 4.3 μg XG eq l−1) were half those in the epipelagic, but we observed relative TEP increments coinciding with the presence of nepheloid layers. These TEP increases were not paralleled by increases in particulate organic carbon, indicating that TEP are likely to act as aggregating agents of the mostly inorganic particles present in these bottom nepheloid layersThis work was funded by projects funded by the Spanish Ministry of Science STORM (CTM2009-09352/MAR), SUMMER (CTM2008-03309/MAR), DOREMI (CTM2012-34294), REMEI (CTM2015-70340-R), ANIMA (CTM2015-65720-R), PEGASO (CTM2012-37615), and Grup consolidat de Recerca de la Generalitat de Catalunya (2014SGR/1179)Peer Reviewe

Wind-induced changes in the dynamics of fluorescent organic matter in the coastal NW Mediterranean

Original research paperMarine biogeochemistry dynamics in coastal marine areas is strongly influenced by episodic events such as rain, intense winds, river discharges and anthropogenic activities. We evaluated in this study the importance of these forcing events on modulating seasonal changes in the marine biogeochemistry of the northwestern coast of the Mediterranean Sea, based on data gathered from a fixed coastal sampling station in the area. A 4-year (2011–2014) monthly sampling at four depths (0.5 m, 20 m, 50 m and 80 m) was performed to examine the time variability of several oceanographic variables: seawater temperature, salinity, inorganic nutrient concentrations (NO3−, PO43 − and SiO2), chlorophyll a (Chl a), dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM). FDOM dynamics was predominantly influenced by upwelling events and mixing processes, driven by strong and characteristic wind episodes. SW wind episodes favored the upwelling of deeper and denser waters into the shallower shelf, providing a surplus of autochthonous humic-like material and inorganic nutrients, whereas northerlies favored the homogenization of the whole shelf water column by cooling and evaporation. These different wind-induced processes (deep water intrusion or mixing), reported along the four sampled years, determined a high interannual environmental variability in comparison with other Mediterranean sampling sites. Graphical abstract Image 1 Download : Download high-res image (344KB)Download : Download full-size imageECOSER (CTM2011-15937-E), DOREMI (CTM2012-342949), SUAVE (CTM2014/ 23456/1) and ANIMA (CTM2015-65720) from the Spanish Ministerio de Economía y Competitividad (MINECO) and the Grup de Recerca Consolidat 2014SGR1179 and 2014SGR1029 financed by the Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) from the Generalitat de Catalunya; (JAEPre_2011_00923) from the Agencia Estatal Consejo Su perior de Investigaciones Científicas (CSIC) and the project FERMIO (MINECO, CTM2014-57334-JIN) co-financed with FEDER fundsVersión del editor3,25

Campaña "Galicia VII". Datos básicos

49 páginas, 9 figuras, 64 tablasDescripción de la campaña.- La campaña oceanográfica se realizó del 18 de Febrero al 7 de Marzo de 1984 a bordo del B/O "García del Cid". En la zona sur hubo viento fuerte del sur y después del noroeste que obligó a refugiarse en puerto, durante el resto de la campaña el viento fue del nordeste con una velocidad media de 16 nudos que se intensificó hacia el final. [...]Comisión Asesora de Investigación Científica y Técnica, proyecto C-3.0019/81.Peer reviewe

Grazing in a turbulent environment: Energy dissipation, encounter rates, and efficacy of feeding currents in Centropages hamatus

5 pages, 4 figures, 2 tablesThe creation of feeding currents by calanoid copepods increases encounter rates of copepods with their food and provides an advantage in dilute nutritional environments. Small-scale turbulence has also been hypothesized to increase the encounter rate between planktonic predators and their food. Centropages hamatus was exposed to turbulent and nonturbulent environments at two prey concentrations to quantify the influence of turbulence on feeding current efficacy. Turbulent energy dissipation rates used in the experiment were in the range of 0.05-0.15 cm2·sec-3. In the nonturbulent environments, feeding currents increased the encounter rates of C. hamatus 3-5 times that of control encounter areas. In turbulent environments, encounter rates were not increased by feeding currents, yet C. hamatus continued to create feeding currents. Energetic calculations indicate a tradeoff in the value of turbulence to a copepod feeding on phytoplankton. While turbulence is probably beneficial at low food concentrations, it may be deleterious at high food concentrationsPeer Reviewe

Impact of aerosols of different origin on marine microbial dynamics in the Mediterranean

Surface Ocean Lower Atmosphere Study Workshop (SOLAS) Workshop on Frontiers in Ocean-Atmosphere Exchange: Air Sea Interface and Fluxes of Mass and Energy, 15-18 May 2017 Cargèse, Corsica, France.-- 1 page, 7 figuresANIMA (Spanish MINECO/FEDER CTM2015-­65720-­R). Project ADEPT (CTM2011-­23458) is also acknowledged. I.M. was the recipient of an FPI fellowship. http://anima.icm.csic.esPeer Reviewe

Seasonal patterns of free-living and attached bacterial activity in the coastal NW Mediterranean

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainMatter in the ocean has traditionally been divided into dissolved or particulate fractions and associated to these, the life-style of bacteria can be classified as free-living (FL) or particle-attached (PA). We followed the size structure of bacterioplankton from September 2010 to June 2013 in a NW Mediterranean Sea coastal site (Blanes Bay Microbial Observatory, BBMO). A monthly sampling was performed in surface waters following bulk seawater, but also size fractionating through 5 different filters: 0.2 – 0.8 – 3.0 – 5.0 – 10.0 µm pore size. Bacterial abundance and production, extracellular enzyme activities, and utilization of sole carbon sources (95 substrates) were determined in these fractions. We observed different patterns of activity in different size fractions. Our results also suggest an important role of meteorological events, such as precipitation, and environmental factors such as temperature, nutrients and chlorophyll a in determining the seasonal patterns of fractionated bacterial activityPeer Reviewe

Mechanisms driving the fate of the organic matter in deep sea waters: quality and quantity of the substrates

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainThree different incubation experiments of 25 days long were conducted during the last FICARAM cruise in 2013. Water was sampled along the Southern Atlantic Ocean from more than 3000 m depth. Four experimental conditions were set for each experiment: K was kept as a control, CL received additions of labile compounds (acetate and glucose), CM got a mixture of twenty organic compounds and CR received a mixture of humic acids as examples of recalcitrant compounds. After 10 days of incubation bacteria population reached the stationary phase. Changes in composition and quality of DOM were tracked by calculating the absorption coefficient a254. While the release of humic like compounds was not remarkable in CR and K conditions, for CM and CL the concentration of aromatic substances increased associated to bacterial growth. Protein-like compounds were generated as a by-product of bacterial metabolism in conditions were the source of C was a mixture of acetate and glucose. Also a 5-components PARAFAC model was validated for the entire transect in order to track the compounds present in our water incubationsPeer Reviewe

Campaña "Galicia VIII". Datos básicos

96 páginasDescripción de la campaña.- La campaña se realizó del 11 de Julio al 8 de Agosto de 1984 a bordo del B/O "García del Cid" abarcando la zona costera del NW de la península ibérica indicada en la figura 1 y una estación (E-2700) que no figura en el mapa. El tiempo, en general, fue bueno, predominando el viento norte como es general en esta época del año, con una velocidad media de 19 nudos, llegando alguna vez a 32 nudos. E1 final de? La campaña coincidió con una purga de mar intensa, localizada principalmente en las bocas de las Rías Bajas. […]Comisión Asesora de Investigación Científica y técnica, proyecto C-3.0019/81Peer reviewe

Growth stimulation of bacterioplankton from deep waters of the NW Mediterranean

Symposium on Integrating New Advances in Mediterranean Oceanography and Marine Biology, 26-29 November 2013, Institut de Ciències del Mar (CSIC), Barcelona, Catalunya, SpainBacteria in the deep ocean are present at very low concentrations, compared to upper layers. A possible limitation of their growth might be the availability or the lability of inorganic or organic nutrients. In order to test this hypothesis, we carried out a set of experiments to study the response of deep-water heterotrophic bacteria to the addition of different organic nutrients. Deep water was collected from the NW Mediterranean Sea in four different cruises during 2012 and 2013 from the same area of the NW Mediterranean. Water was filtered through 0.6 μm to avoid the presence of predators. One-liter microcosms were incubated during 2-3 days in the dark at in situ temperature. Duplicate treatments consisted in the addition of different carbon sources (24 μM C), or inorganic nutrients (ammonium, nitrate and phosphate, final concentrations 2.4, 44.7 and 0.6-1.29 μM, respectively). The results of the first experiments showed that a carbon source (glucose) and not inorganic nutrients, stimulated bacterial growth. This suggested that bacterial limitation was limited by carbon. In the following experiments, a more detailed analysis of the carbon sources that could stimulate the growth of bacterioplankton in deep waters was done. The results of those experiments suggest that bacteria prefer mainly two sources of dissolved organic matter: 1) derived from phytoplanktonic cultures, or 2) water collected from the deep chlorophyll maximum filtered through 0.2 μm. This might be very likely due to its higher complexity, compared to glucose, cellulose or chitin, but also to the higher lability in comparison to dissolved organic matter of river originPeer Reviewe

Coastal Bacterioplankton Metabolism Is Stimulated Stronger by Anthropogenic Aerosols than Saharan Dust

17 pages, 9 figures, 3 tables, supplemental material https://www.frontiersin.org/articles/10.3389/fmicb.2017.02215/full#supplementary-materialIn oligotrophic regions, such as the Mediterranean Sea, atmospheric deposition has the potential to stimulate heterotrophic prokaryote growth and production in surface waters, especially during the summer stratification period. Previous studies focused on the role of leaching nutrients from mineral particles of Saharan (S) origin, and were restricted to single locations at given times of the year. In this study, we evaluate the effect of atmospheric particles from diverse sources and with a markedly different chemical composition [S dust and anthropogenic (A) aerosols] on marine planktonic communities from three locations of the northwestern Mediterranean with contrasted anthropogenic footprint. Experiments were also carried out at different times of the year, considering diverse initial conditions. We followed the dynamics of the heterotrophic community and a range of biogeochemical and physiological parameters in six experiments. While the effect of aerosols on bacterial abundance was overall low, bacterial heterotrophic production was up to 3.3 and 2.1 times higher in the samples amended with A and S aerosols, respectively, than in the controls. Extracellular enzymatic activities [leu-aminopeptidase (AMA) and β-glucosidase (β-Gl)] were also enhanced with aerosols, especially from A origin. AMA and β-Gl increased up to 7.1 in the samples amended with A aerosols, and up to 1.7 and 2.1 times, respectively, with S dust. The larger stimulation observed with A aerosols might be attributed to their higher content in nitrate. However, the response was variable depending the initial status of the seawater. In addition, we found that both A and S aerosols stimulated bacterial abundance and metabolism significantly more in the absence of competitors and predatorsThis study was supported by the Spanish Ministerio de Economía y Competitividad through the projects ADEPT (CTM2011-23458), DOREMI (CTM2012-342949), and ANIMA (CTM2015-65720-R, MINECO/FEDER, EU). IM acknowledges the FPI Spanish scholarship program for a pre-doctoral grant (BES 2012-052976). SN received financial support from the National Counsel of Technological and Scientific Development (CNPq) of Brazil. EDS-P was economically supported by the Consejo Nacional de Ciencia y Tecnologia (CONACyT) of MexicoPeer Reviewe