Temporal variability of diazotroph community composition in the upwelling region off NW Iberia.

Knowledge of the ecology of N2-fixing (diazotrophic) plankton is mainly limited to oligotrophic (sub)tropical oceans. However, diazotrophs are widely distributed and active throughout the global ocean. Likewise, relatively little is known about the temporal dynamics of diazotrophs in productive areas. Between February 2014 and December 2015, we carried out 9 one-day samplings in the temperate northwestern Iberian upwelling system to investigate the temporal and vertical variability of the diazotrophic community and its relationship with hydrodynamic forcing. In downwelling conditions, characterized by deeper mixed layers and a homogeneous water column, non-cyanobacterial diazotrophs belonging mainly to nifH clusters 1G (Gammaproteobacteria) and 3 (putative anaerobes) dominated the diazotrophic community. In upwelling and relaxation conditions, affected by enhanced vertical stratification and hydrographic variability, the community was more heterogeneous vertically but less diverse, with prevalence of UCYN-A (unicellular cyanobacteria, subcluster 1B) and non-cyanobacterial diazotrophs from clusters 1G and 3. Oligotyping analysis of UCYN-A phylotype showed that UCYN-A2 sublineage was the most abundant (74%), followed by UCYN-A1 (23%) and UCYN-A4 (2%). UCYN-A1 oligotypes exhibited relatively low frequencies during the three hydrographic conditions, whereas UCYN-A2 showed higher abundances during upwelling and relaxation. Our findings show the presence of a diverse and temporally variable diazotrophic community driven by hydrodynamic forcing in an upwelling system

A acidificación dos océanos: un contexto real para traballar na aula

A acidifcación dos océanos é un problema ambiental derivado fundamentalmente da queima de combustibles fósiles e das consecuentes emisións de CO2 á atmosfera. Foi na última década cando a humanidade comezou a ser verdadeiramente consciente do problema. Polo tanto, trátase dunha cuestión de actualidade e bastante descoñecida xa que recentemente a comunidade científica comezou a traballar nesta liña delimitando o marco desta grave consecuencia para os océanos (Orr et al., 2005; Doney et al., 2009)S

Vertical zonation of bacterial assemblages attributed to physical stratification during the summer relaxation of the coastal upwelling off Galicia (NW Spain)

Research articleWe combined flow cytometry, CARD-FISH, and 16S rRNA gene tag pyrosequencing to investigate bacterioplankton dynamics along a transect in shelf waters off A Coruña (Galicia, NW Spain). Over five days (16-20th July 2012) we sampled during the relaxation of a summer upwelling pulse, providing an opportunity to examine the impact of pulses of cold nutrient-rich water into coastal microbial communities. The hydrographic conditions, characterized by intense density stratification of surface waters and the presence of a deep chlorophyll maximum (DCM) at 20–30 m, were relatively maintained over the sampling period. Indeed, bacterial abundance and composition displayed low day to day variation. Alpha diversity analysis suggested that species richness and diversity increased from coastal to shelf stations and from the surface down to the coastal DCM, which could be caused by the mixing of upwelled bacteria with the coastal surface waters. SAR11, SAR86, and Roseobacter were the most abundant bacteria detected in the samples by using CARD-FISH. The assemblages observed by pyrosequencing displayed a strong vertical zonation along the transect. Rhodobacteraceae (under class Alphaproteobacteria) and Bacteriodetes dominated the surface waters and decreased during the upwelling pulse, while SAR 86 (under class Gammaproteobacteria), Actinobacteria and SAR11 clade increased their relative abundance at the coastal DCM with upwelling relaxation, particularly at the shelf stations. Bacterial assemblages from surface waters were associated with higher temperature and light conditions, while coastal DCM assemblages were rather associated to salinity, inorganic nutrients and a diatom-bloom leading to high chlorophyll-a. Our findings suggest that the vertical variability in environmental conditions induced by the intense density stratification, the exportation of warmer and less saline surface water from the rias to the adjacent shelf, and the fertilizing effect of recently upwelled water at the deeper layer, determined the composition of distinct bacterial assemblages at the subsurface and DCM layers.XUNTA DE GALICIA (O9MMA 027604PR, 10MMA604024PR), IEO (PROYECTO RADIALES) y PLAN NACIONAL (MODUPLAN CTM2011-24008)Versión del editor2,24

Short term variability of bacterial communities in the shelf waters off Galicia (NW Iberian Peninsula): Patterns and drivers shaping the diversity

PósterEcological and biogeochemical processesEcological and biogeochemical processes in the ocean are dependent on a diverse assemblage of microbes, including members of Bacteria (Glöckner et al, 2012). These bacterial assemblages occurs in vast numbers and represent a huge genetic diversity, fulfilling a wide of ecological roles in the marine system such as carbon geochemical cycle and energy transfer into higher trophic levels.We combined flow cytometry, CARD-FISH and 16S rRNA gene tag pyrosequencing to investigate the short-term variability of the bacterial communities in samples collected along a transect in the shelf off NW Iberian Peninsula over one week

Temporal variability of diazotroph community composition in the upwelling region off NW Iberia

Knowledge of the ecology of N 2 -fixing (diazotrophic) plankton is mainly limited to oligotrophic (sub)tropical oceans. However, diazotrophs are widely distributed and active throughout the global ocean. Likewise, relatively little is known about the temporal dynamics of diazotrophs in productive areas. Between February 2014 and December 2015, we carried out 9 one-day samplings in the temperate northwestern Iberian upwelling system to investigate the temporal and vertical variability of the diazotrophic community and its relationship with hydrodynamic forcing. In downwelling conditions, characterized by deeper mixed layers and a homogeneous water column, non-cyanobacterial diazotrophs belonging mainly to nifH clusters 1G (Gammaproteobacteria) and 3 (putative anaerobes) dominated the diazotrophic community. In upwelling and relaxation conditions, affected by enhanced vertical stratification and hydrographic variability, the community was more heterogeneous vertically but less diverse, with prevalence of UCYN-A (unicellular cyanobacteria, subcluster 1B) and non-cyanobacterial diazotrophs from clusters 1G and 3. Oligotyping analysis of UCYN-A phylotype showed that UCYN-A2 sublineage was the most abundant (74%), followed by UCYN-A1 (23%) and UCYN-A4 (2%). UCYN-A1 oligotypes exhibited relatively low frequencies during the three hydrographic conditions, whereas UCYN-A2 showed higher abundances during upwelling and relaxation. Our findings show the presence of a diverse and temporally variable diazotrophic community driven by hydrodynamic forcing in an upwelling system.Xunta de Galicia | Ref. EM2013/021Ministerio de Economía, Industria y Competitividad | Ref. CTM2016-75451-C2-1-RMinisterio de Educación, Cultura y Deporte | Ref. FPU13/01674Ministerio de Educación, Cultura y Deporte | Ref. EST16/00142Universidad de Vigo | Ref. Axudas á investigación 201

Factors controlling the community structure of picoplankton in contrasting marine environments

The effect of inorganic nutrients on planktonic assemblages has traditionally relied on concentrations rather than estimates of nutrient supply. We combined a novel dataset of hydrographic properties, turbulent mixing, nutrient concentration, and picoplankton community composition with the aims of (i) quantifying the role of temperature, light, and nitrate fluxes as factors controlling the distribution of autotrophic and heterotrophic picoplankton subgroups, as determined by flow cytometry, and (ii) describing the ecological niches of the various components of the picoplankton community. Data were collected at 97 stations in the Atlantic Ocean, including tropical and subtropical open-ocean waters, the northwestern Mediterranean Sea, and the Galician coastal upwelling system of the northwest Iberian Peninsula. A generalized additive model (GAM) approach was used to predict depth-integrated biomass of each picoplankton subgroup based on three niche predictors: sea surface temperature, averaged daily surface irradiance, and the transport of nitrate into the euphotic zone, through both diffusion and advection. In addition, niche overlap among different picoplankton subgroups was computed using nonparametric kernel density functions. Temperature and nitrate supply were more relevant than light in predicting the biomass of most picoplankton subgroups, except for Prochlorococcus and low-nucleic-acid (LNA) prokaryotes, for which irradiance also played a significant role. Nitrate supply was the only factor that allowed the distinction among the ecological niches of all autotrophic and heterotrophic picoplankton subgroups. Prochlorococcus and LNA prokaryotes were more abundant in warmer waters (>20 ∘C) where the nitrate fluxes were low, whereas Synechococcus and high-nucleic-acid (HNA) prokaryotes prevailed mainly in cooler environments characterized by intermediate or high levels of nitrate supply. Finally, the niche of picoeukaryotes was defined by low temperatures and high nitrate supply. These results support the key role of nitrate supply, as it not only promotes the growth of large phytoplankton, but it also controls the structure of marine picoplankton communities.Ministerio de Economía y Competitividad | Ref. CTM2012-30680Ministerio de Economía y Competitividad | Ref. CTM2008-0626I-C03-01Ministerio de Economía y Competitividad | Ref. REN2003-09532-C03-01Ministerio de Economía y Competitividad | Ref. CTM2004-05174 -C02Ministerio de Economía y Competitividad | Ref. CTM2011-25035Xunta de Galicia | Ref. 09MMA027604PRXunta de Galicia | Ref. EM2013/021European Commission | Ref. FP7, n. 261860Ministerio de Economía y Competitividad | Ref. FJCI-641 2015-2571

5to. Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad. Memoria académica

El V Congreso Internacional de Ciencia, Tecnología e Innovación para la Sociedad, CITIS 2019, realizado del 6 al 8 de febrero de 2019 y organizado por la Universidad Politécnica Salesiana, ofreció a la comunidad académica nacional e internacional una plataforma de comunicación unificada, dirigida a cubrir los problemas teóricos y prácticos de mayor impacto en la sociedad moderna desde la ingeniería. En esta edición, dedicada a los 25 años de vida de la UPS, los ejes temáticos estuvieron relacionados con la aplicación de la ciencia, el desarrollo tecnológico y la innovación en cinco pilares fundamentales de nuestra sociedad: la industria, la movilidad, la sostenibilidad ambiental, la información y las telecomunicaciones. El comité científico estuvo conformado formado por 48 investigadores procedentes de diez países: España, Reino Unido, Italia, Bélgica, México, Venezuela, Colombia, Brasil, Estados Unidos y Ecuador. Fueron recibidas un centenar de contribuciones, de las cuales 39 fueron aprobadas en forma de ponencias y 15 en formato poster. Estas contribuciones fueron presentadas de forma oral ante toda la comunidad académica que se dio cita en el Congreso, quienes desde el aula magna, el auditorio y la sala de usos múltiples de la Universidad Politécnica Salesiana, cumplieron respetuosamente la responsabilidad de representar a toda la sociedad en la revisión, aceptación y validación del conocimiento nuevo que fue presentado en cada exposición por los investigadores. Paralelo a las sesiones técnicas, el Congreso contó con espacios de presentación de posters científicos y cinco workshops en temáticas de vanguardia que cautivaron la atención de nuestros docentes y estudiantes. También en el marco del evento se impartieron un total de ocho conferencias magistrales en temas tan actuales como la gestión del conocimiento en la universidad-ecosistema, los retos y oportunidades de la industria 4.0, los avances de la investigación básica y aplicada en mecatrónica para el estudio de robots de nueva generación, la optimización en ingeniería con técnicas multi-objetivo, el desarrollo de las redes avanzadas en Latinoamérica y los mundos, la contaminación del aire debido al tránsito vehicular, el radón y los riesgos que representa este gas radiactivo para la salud humana, entre otros

Quantifying the overestimation of planktonic N2 fixation due to contamination of 15N2 gas stocks

The 15N2-tracer assay [Montoya et al. (1996) A simple, high-precision, high-sensitivity tracer assay for N2 fixation. Appl. Environ. Microbiol., 62, 986–993.] is the most used method for measuring biological N2 fixation in terrestrial and aquatic environments. The reliability of this technique depends on the purity of the commercial 15N2 gas stocks used. However, Dabundo et al. [(2014) The contamination of commercial 15N2 gas stocks with 15N-labeled nitrate and 142 ammonium and consequences for nitrogen fixation measurements. PLoS One, 9, e110335.] reported the contamination of some of these stocks with labile 15N-labeled compounds (ammonium, nitrate and/or nitrite). Considering that the tracer assay relies on the conversion of isotopically labeled 15N2 into organic nitrogen, this contamination may have led to overestimated N2 fixation rates. We conducted laboratory and field experiments in order to (i) test the susceptibility of 15N contaminants to assimilation by non-diazotroph organisms and (ii) determine the potential overestimation of the N2 fixation rates estimated in the field. Our findings indicate that the contaminant 15N-compounds are assimilated by non-diazotrophs organisms, leading to an overestimation of N2 fixation rates in the field up to 16-fold under hydrographic conditions of winter mixing

Temporal variability of diazotroph community composition in the upwelling region off NW Iberia

Abstract Knowledge of the ecology of N2-fixing (diazotrophic) plankton is mainly limited to oligotrophic (sub)tropical oceans. However, diazotrophs are widely distributed and active throughout the global ocean. Likewise, relatively little is known about the temporal dynamics of diazotrophs in productive areas. Between February 2014 and December 2015, we carried out 9 one-day samplings in the temperate northwestern Iberian upwelling system to investigate the temporal and vertical variability of the diazotrophic community and its relationship with hydrodynamic forcing. In downwelling conditions, characterized by deeper mixed layers and a homogeneous water column, non-cyanobacterial diazotrophs belonging mainly to nifH clusters 1G (Gammaproteobacteria) and 3 (putative anaerobes) dominated the diazotrophic community. In upwelling and relaxation conditions, affected by enhanced vertical stratification and hydrographic variability, the community was more heterogeneous vertically but less diverse, with prevalence of UCYN-A (unicellular cyanobacteria, subcluster 1B) and non-cyanobacterial diazotrophs from clusters 1G and 3. Oligotyping analysis of UCYN-A phylotype showed that UCYN-A2 sublineage was the most abundant (74%), followed by UCYN-A1 (23%) and UCYN-A4 (2%). UCYN-A1 oligotypes exhibited relatively low frequencies during the three hydrographic conditions, whereas UCYN-A2 showed higher abundances during upwelling and relaxation. Our findings show the presence of a diverse and temporally variable diazotrophic community driven by hydrodynamic forcing in an upwelling system