Regularidades estacionales en la producción primaria y los parámetros fotosintéticos en una estación costera del NO Mediterráneo

We carried out monthly photosynthesis-irradiance (P-E) experiments with the 14C-method for 12 years (2003–2014) to determine the photosynthetic parameters and primary production of surface phytoplankton in the Blanes Bay Microbial Observatory, a coastal sampling station in the NW Mediterranean Sea. Our goal was to obtain seasonal trends and to establish the basis for detecting future changes of primary production in this oligotrophic area. The maximal photosynthetic rate PBmax ranged 30-fold (0.5-15 mg C mg Chl a–1 h–1), averaged 3.7 mg C mg Chl a–1 h–1 (±0.25 SE) and was highest in August and lowest in April and December. We only observed photoinhibition twice. The initial or light-limited slope of the P-E relationship, αB, was low, averaging 0.007 mg C mg Chl a–1 h–1 (μmol photons m–2 s–1)–1 (±0.001 SE, range 0.001-0.045) and showed the lowest values in spring (April-June). The light saturation parameter or saturation irradiance, EK, averaged 711 μmol photons m–2 s–1 (± 58.4 SE) and tended to be higher in spring and lower in winter. Phytoplankton assemblages were typically dominated by picoeukaryotes in early winter, diatoms in late autumn and late winter, dinoflagellates in spring and cyanobacteria in summer. Total particulate primary production averaged 1.45 mg C m-3 h–1 (±0.13 SE) with highest values in winter (up to 8.50 mg C m-3 h–1) and lowest values in summer (summer average, 0.30 mg C m-3 h–1), while chlorophyll-specific primary production averaged 2.49 mg C mg Chl a–1 h–1 (±0.19, SE) and peaked in summer (up to 12.0 mg C mg Chl a–1 h–1 in August). 14C-determined phytoplankton growth rates varied between ca. 0.3 d–1 in winter and 0.5 d–1 in summer and were within 60-80% of the maximal rates of growth, based on PBmax. Chlorophyll a was a good predictor of primary production only in the winter and autumn. Seasonality appeared to explain most of the variability in the studied variables, while phytoplankton composition played a minor role. Daily integrated primary production was fairly constant throughout the year: similar to previous oxygen-based estimates in winter but considerably lower than these in summer. The difference between 14C- and oxygen-based estimates of primary production could be explained by community respiration. Annually integrated primary production amounted to a rather modest 48 g C m–2 yr–1 (equivalent to 130 mg C m–2 d–1). Although no interannual patterns were detected, our work soundly establishes the seasonal trends for the coastal NW Mediterranean, therefore setting the basis for future detection of change.Hemos llevado a cabo mediciones mensuales de la relación entre fotosíntesis e irradiancia (curvas P-E) con el método del 14C durante 12 años (2003-2014), para obtener los parámetros fotosintéticos y la producción primaria del fitoplancton superficial en el Observatorio Microbiano de la Bahía de Blanes, una estación de muestreo costera en el noroeste del Mediterráneo. Nuestro objetivo era determinar las tendencias estacionales y establecer la línea de base para detectar cambios futuros de la producción primaria en esta área oligotrófica. La tasa fotosintética máxima PBmaxosciló 30 veces (0.5 a 15 mg C mg Chl a–1 h–1), con un promedio de 3.7 mg C mg Chl a–1 h–1 (±0.25, error estándar), y fue máxima en agosto y mínima en abril y diciembre. Sólo se observó fotoinhibicion dos veces. La pendiente inicial de la curva P-E, αB, fue baja, con un promedio de 0.007 mg C mg Chl a–1 h–1 (µmol fotones m–2 s–1)–1 (error estándar ±0.001, rango de 0.001-0.045) y presentó los valores más bajos en primavera (abril-junio). El parámetro de saturación de irradiancia, EK, presentó un promedio de 711 µmol fotones m–2 s–1 (±58.4, error estándar) y tendió a ser mayor en primavera y menor en invierno. El fitoplancton estuvo típicamente dominado por picoeucariotas a principios de invierno, diatomeas a finales de otoño y en el invierno avanzado, dinoflagelados en primavera, y cianobacterias en verano. La producción primaria particulada total promedió 1.45 m–3 h–1 (±0.13 error estándar) con máximos en invierno (hasta 8.50 mg C m–3 h–1) y mínimos en verano (media en verano, 0.30 mg C m–3 h–1), mientras que la producción primaria por unidad de clorofila promedió 2.49 mg C mg Chl a–1 h–1 (±0.19, error estándar) y alcanzó su punto máximo en verano (hasta 12.0 mg C mg Chl a–1 h–1 en agosto). Las tasas de crecimiento del fitoplancton determinadas por 14C oscilaron entre ca. 0.3 d–1 en invierno y 0.5 d–1 en verano, siendo 60-80% de las tasas máximas de crecimiento basadas en los valores de PBmax. La clorofila a resultó ser un buen predictor de la producción primaria sólo en el invierno y el otoño. La estacionalidad explica la mayor parte de la variabilidad en las variables estudiadas, mientras que la composición del fitoplancton juega un papel menor. La producción primaria integrada diaria fue bastante constante durante todo el año, similar a estimaciones anteriores con mediciones de oxígeno en invierno, pero considerablemente más bajas en verano. La diferencia entre las estimaciones de la producción primaria por 14C y las estimaciones en base al oxígeno podrían explicarse por la respiración de la comunidad. Anualmente la producción primaria integrada ascendió a valores más bien modestos de 48 g C m–2 año–1 (equivalentes a 130 mg C m–2 d–1). Aunque no se detectaron patrones interanuales, nuestro trabajo establece las tendencias estacionales para la producción primaria en el litoral Mediterráneo noroccidental, y supone la línea de base para la detección de cambios futuros

Seasonal impact of grazing, viral mortality, resource availability and light on the group-specific growth rates of coastal Mediterranean bacterioplankton

Estimation of prokaryotic growth rates is critical to understand the ecological role and contribution of different microbes to marine biogeochemical cycles. However, there is a general lack of knowledge on what factors control the growth rates of different prokaryotic groups and how these vary between sites and along seasons at a given site. We carried out several manipulation experiments during the four astronomical seasons in the coastal NW Mediterranean in order to evaluate the impact of grazing, viral mortality, resource competition and light on the growth and loss rates of prokaryotes. Gross and net growth rates of different bacterioplankton groups targeted by group-specific CARD-FISH probes and infrared microscopy (for aerobic anoxygenic phototrophs, AAP), were calculated from changes in cell abundances. Maximal group-specific growth rates were achieved when both predation pressure and nutrient limitation were experimentally minimized, while only a minimal effect of viral pressure on growth rates was observed; nevertheless, the response to predation removal was more remarkable in winter, when the bacterial community was not subjected to nutrient limitation. Although all groups showed increases in their growth rates when resource competition as well as grazers and viral pressure were reduced, Alteromonadaceae consistently presented the highest rates in all seasons. The response to light availability was generally weaker than that to the other factors, but it was variable between seasons. In summer and spring, the growth rates of AAP were stimulated by light whereas the growth of the SAR11 clade (likely containing proteorhodopsin) was enhanced by light in all seasons. Overall, our results set thresholds on bacterioplankton group-specific growth and mortality rates and contribute to estimate the seasonally changing contribution of various bacterioplankton groups to the function of microbial communities. Our results also indicate that the least abundant groups display the highest growth rates, contributing to the recycling of organic matter to a much greater extent than what their abundances alone would predict.En prensa2,92

COVID-19 lockdown moderately increased oligotrophy at a marine coastal site

8 pages, 4 figures, 2 figures, supplementary figures https://doi.org/10.1016/j.scitotenv.2021.151443.COVID-19 has led to global population lockdowns that have had indirect effects on terrestrial and marine fauna, yet little is known on their effects on marine planktonic communities. We analysed the effect of the spring 2020 lockdown in a marine coastal area in Blanes Bay, NW Mediterranean. We compared a set of 23 oceanographic, microbial and biogeochemical variables sampled right after the strict lockdown in Spain, with data from the previous 15 years after correcting for long-term trends. Our analysis shows a series of changes in the microbial communities which may have been induced by the combination of the decreased nitrogen atmospheric load, the lower wastewater flux and the reduced fishing activity in the area, among other factors. In particular, we detected a slight decrease beyond the long-term trend in chlorophyll a, in the abundance of several microbial groups (phototrophic nanoflagellates and total prokaryotes) and in prokaryotic activity (heterotrophic prokaryotic production and β-glucosidase activity) which, as a whole, resulted in a moderate increase of oligotrophy in Blanes Bay after the lockdown.Data from the specific sampling in 2020 were supported by the MIAU project of the Spanish Ministerio de Ciencia e Innovación, MICINN (RTI2018-101025-B-I00), while previous years were supported by many Spanish and EU projects. Other projects of the MICINN also supported this research: DOGMA (PID2020-112653GB-I00), DIVAS (PID2019-108457RB-I00), and HICCUP (RTI2018-095083-B-I00). We thank Amanda Con and Juan Rodríguez for providing data of the Blanes WWTP. We sincerely thank Irene Forn, Carolina Antequera, Arturo Lucas, Elisabet Laia Sà and Vanessa Balagué for their invaluable laboratory work. The work of the authors was supported by Generalitat de Catalunya Grups de Recerca Consolidats 2017SGR1568 and 2017SGR1011. This study acknowledges institutional support from the “Severo Ochoa Centre of Excellence” accreditation (CEX2019-000928-S).Peer reviewe

Guia d’identificació del plàncton

68 pages, figuresSota les onades de l’oceà es belluguen una immensitat d’organismes. Molts els coneixem però, t’has imaginat mai que alguns arribin a ser tan petits que no poden ser vistos a ull nu? Submergeix-te en el mar d’espècies que es deixen portar pel vaivé de les onades. Descobriràs el plàncton, un món fascinant!Un projecte de l’Institut de Ciències del Mar (ICM-CSIC) i l’Escola del Mar (Ajuntament de Badalona), amb la col·laboració de la Fundación Española para la Ciencia y la Tecnología (FECYT) - Ministerio de Ciencia e Innovación, i amb el suport institucional de l’acreditació AEI ‘Severo Ochoa Centre of Excellence’ (CEX2019-000928-S)Peer reviewe

High amino acid osmotrophic incorporation by marine eukaryotic phytoplankton revealed by click-chemistry

pages, 7 figures.-- Data Availability Statement: Raw sequences are publicly available at the European Nucleotide Archive (https://www.ebi.ac.uk/ena) under the accession number PRJEB63614. The datasets generated for this study are available on request to the corresponding authors.The osmotrophic uptake of dissolved organic compounds in the ocean is considered to be dominated by heterotrophic prokaryotes, whereas the role of planktonic eukaryotes is still unclear. We explored the capacity of natural eukaryotic plankton communities to incorporate the synthetic amino acid L-homopropargylglycine (HPG, analogue of methionine) using biorthogonal noncanonical amino acid tagging (BONCAT), and compared it with prokaryotic HPG use throughout a 9-day survey in the NW Mediterranean. BONCAT allows to fluorescently identify translationally active cells, but it has never been applied to natural eukaryotic communities. We found a large diversity of photosynthetic and heterotrophic eukaryotes incorporating HPG into proteins, with dinoflagellates and diatoms showing the highest percentages of BONCAT-labelled cells (49 ± 25% and 52 ± 15%, respectively). Among them, pennate diatoms exhibited higher HPG incorporation in the afternoon than in the morning, whereas small (≤5 μm) photosynthetic eukaryotes and heterotrophic nanoeukaryotes showed the opposite pattern. Centric diatoms (e.g., Chaetoceros, Thalassiosira, Lauderia spp.) dominated the eukaryotic HPG incorporation due to their high abundances and large sizes, accounting for up to 86% of the eukaryotic BONCAT signal, and strongly correlating with bulk 3H-leucine uptake rates. When including prokaryotes, eukaryotes were estimated to account for 19–31% of the bulk BONCAT signal. Our results evidence a large complexity in the osmotrophic uptake of HPG, which varies over time within and across eukaryotic groups, and highlights the potential of BONCAT to quantify osmotrophy and protein synthesis in complex eukaryotic communitiesThis work was funded by the Spanish Ministry of Science, Innovation and Universities (MICINN) through the MIAU (RTI2018-101025-30-B-I00) and MICOLOR (PID2021-125469NB-C31) projects and the Ramon y Cajal contract to C.R.G. (RYC2019-026758-I), with funding from the Spanish Government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S). C.M. was supported by the Juan de la Cierva-formación fellowship (FJC2021-047745-34 I), funded by the Spanish Ministry of Science and Innovation (MCIN/AEI) and the EU (“NextGenerationEU”/PRTR)Peer reviewe

El compromís de l’ICM amb la igualtat de gènere en la recerca marina

2 pages, 1 figure[EN] Despite the drive towards equality between women and men in research institutions in recent years and the progress that has been made, there is still a long road ahead. Science is still associated with the male image, and women’s work and contributions are often invisible. Like many other spheres of society, research institutions contribute to the structural re(production) of gender inequalities. Women and men each tend to have more presence in certain scientific fields, with the horizontal segregation that this involves. Furthermore, the “glass ceiling” (the invisible barrier that hinders women’s access to the highest levels of decision-making or responsibility, limiting their professional careers) causes vertical segregation. Staying in research is an obstacle course in which there is a constant trickle of skills and talents, which is exacerbated for women. Moreover, research often seems blind to the gender dimension in its approach, content and analysis. […][ES] A pesar del impulso de la igualdad entre mujeres y hombres en las instituciones de investigación en los últimos años y de los avances logrados, aún queda un largo camino por recorrer. La ciencia constituye todavía un ámbito asociado a la imagen masculina, invisibilizando con frecuencia el trabajo y las aportaciones de las mujeres. Como muchas otras esferas de la sociedad, las instituciones de investigación contribuyen a la re(producción) estructural de les desigualdades de género. Mujeres y hombres tienden a concentrarse en determinados campos científicos con la segregación horizontal que ello implica. Por otra parte, el llamado “techo de cristal” –la barrera invisible que dificulta u obstaculiza el acceso de las mujeres a los niveles más altos de poder, de decisión o de responsabilidad, limitando sus carreras profesionales–, materializa la segregación vertical. La permanencia en la investigación es una carrera de obstáculos en la que se produce un goteo constante de capacidades y talentos, que se agrava para las mujeres. Además, la investigación parece a menudo ciega a la importancia de considerar la dimensión de género en su abordaje, contenido y análisis. […][CAT] Malgrat l’impuls envers la igualtat a les institucions de recerca dels darrers anys i els avenços assolits, encara hi ha un llarg camí per recórrer. La ciència constitueix encara un àmbit associat a la imatge masculina, invisibilitzant sovint el treball i les aportacions de les dones. Com moltes altres esferes de la societat, les institucions de recerca contribueixen a la re(producció) estructural de les desigualtats de gènere. Dones i homes tendeixen a concentrar-se en determinats camps científics amb la segregació horitzontal que això implica. Per altra banda, l’anomenat “sostre de vidre” –la barrera invisible que dificulta o obstaculitza l’accés de les dones als nivells més alts de poder, de decisió o de responsabilitat, encotillant les seves carreres professionals–, materialitza la segregació vertical. La permanència en la recerca és una carrera d’obstacles on es produeix un degoteig constant de capacitats i talents, agreujat entre les dones. A més, la recerca sembla sovint cega a la importància de considerar la dimensió de gènere en el seu abordatge, contingut i anàlisi. […]Peer reviewe

Un viatge a l'Antàrtida

Charla en la Escola de Teixits de punt de Canet de Mar con motivo del Dia de la Ciència a les EscolesPeer Reviewe

Un viatge a l'Antàrtida

Charla divulgativa en el marco del Dia de la Ciència a les Escoles - Setmana de la Ciència, Canet de MarPeer Reviewe

Annual variability in light modulation of bacterial heterotrophic activity in surface northwestern Mediterranean waters

13 pages, 7 figures, 2 tablesThe effect of photosynthetically available radiation (PAR; 400–700 nm) and ultraviolet radiation (UVR; 280–400 nm) on marine bacterial heterotrophic activity was assessed monthly throughout a seasonal cycle in Blanes Bay (northwestern Mediterranean Sea). Seawater samples amended with 3H-leucine were exposed to solar radiation under three radiation treatments: PAR + UVR (280–700 nm), PAR + UVA (320–700 nm), and PAR only. Parallel reference incubations in the dark and under a fixed artificial light source (PAR only) were also performed. Exposure to high UVR doses caused strong inhibition of 3H-leucine incorporation rates (LIR), whereas natural PAR doses did not cause overall significant effects. Within UVR, UVA radiation accounted for most of the reduction in LIR, and this effect was modulated by the proportionality of the experimental light to the previous light exposure history of the samples. Constant (artificial) PAR-only exposure led to a general but seasonally variable increase in bacterial heterotrophic production compared to the dark controls, with large increases in spring and lower changes during summer. This pattern was likely caused by the stimulation of the bacterial group Gammaproteobacteria, which showed higher numbers of cells active in 3H-leucine uptake after light exposure. Again, the previous light history of the samples seemed to partly explain the measured effects. Overall, our results show variable responses of bacterial activities to light manipulations, depending on seasonally changing light conditions and communities, and stress the importance of realistic simulation of light exposure conditions for ecosystem-relevant photobiological studies with microbial planktonThis work has been supported by the Spanish Ministry of Science and Innovation through projects ‘‘Fuentes de Materia Orgánica, Diversidad microbiana y funcionamiento (Respiración y Uso del Carbono) del ecosistema marino pelágico costero’’–MODIVUS (Ciencias y Tecnologías Marinas–CTM2005-04795/MAR), ‘‘Surface Mixing Modulation of the Exposure to Solar Radiation’’–SUMMER (Ciencias y Tecnologías Marinas–CTM2008-03309/MAR) and by a Ph.D. studentship to C.R.-G.Peer reviewe

Observando los polos : Una visión integral del conocimiento de las zonas polares y sobre las alteraciones que están sufriendo debido al cambio global

317 pagesLas zonas polares, principales responsables del clima de nuestro planeta, están sufriendo cambios drásticos en su naturaleza debido a su alta sensibilidad al cambio global, que afectan directamente a la dinámica climática, oceanográfica y ambiental de latitudes extrapolares. El presente libro pretende dar una visión integral y multidisciplinar del estado del conocimiento de las zonas árticas y antárticas: su evolución geológica, los acuciantes problemas de contaminación de estos territorios, la caracterización de los diversos ecosistemas terrestres y marinos, así como la evolución pasada y futura del clima polar. El objetivo final es explicar, de forma clara y amena, las similitudes y diferencias entre ambos polos y concienciar sobre las alteraciones que están sufriendo debido al cambio global. Asimismo, se dan a conocer las investigaciones, de gran relevancia científica y social, realizadas por el personal científico y técnico del Consejo Superior de Investigaciones Científicas (CSIC), acercándonos a la historia y situación actual de la investigación polar en EspañaPeer reviewe