Search results

Spanish Ministry of Economy and Competitiveness (projects ESTRESX CTM2012-32603 and CLIMPACT CGL2014-54246-C2-1-R). Ramón y Cajal contract (RYC-2013-14714) funded by the Spanish Ministry of Economy and Competitiveness and the Regional Government of the Balearic Islands. ; Peer Reviewed

Xabier Irigoien et al. ; With a current estimate of ~1,000 million tons, mesopelagic fishes likely dominate the world total fishes biomass. However, recent acoustic observations show that mesopelagic fishes biomass could be significantly larger than the current estimate. Here we combine modelling and a sensitivity analysis of the acoustic observations from the Malaspina 2010 Circumnavigation Expedition to show that the previous estimate needs to be revised to at least one order of magnitude higher. We show that there is a close relationship between the open ocean fishes biomass and primary production, and that the energy transfer efficiency from phytoplankton to mesopelagic fishes in the open ocean is higher than what is typically assumed. Our results indicate that the role of mesopelagic fishes in oceanic ecosystems and global ocean biogeochemical cycles needs to be revised as they may be respiring ~10% of the primary production in deep waters. ; This research was conducted by the Malaspina 2010 Expedition project, funded by the Spanish Ministry of Economy and Competitiveness (Consolider-Ingenio 2010, CSD2008-00077). Additional financial support was provided by the Basque Country Government and by AZTI-Tecnalia ; Peer Reviewed

Carlos M. Duarte et al. ; The Arctic marine ecosystem contains multiple elements that present alternative states. The most obvious of which is an Arctic Ocean largely covered by an ice sheet in summer versus one largely devoid of such cover. Ecosystems under pressure typically shift between such alternative states in an abrupt, rather than smooth manner, with the level of forcing required for shifting this status termed threshold or tipping point. Loss of Arctic ice due to anthropogenic climate change is accelerating, with the extent of Arctic sea ice displaying increased variance at present, a leading indicator of the proximity of a possible tipping point. Reduced ice extent is expected, in turn, to trigger a number of additional tipping elements, physical, chemical, and biological, in motion, with potentially large impacts on the Arctic marine ecosystem. ; This is a contribution to the Arctic Tipping Points project (www.eu-atp.org) funded by FP7 of the European Union (contract #226248). ; Peer reviewed

The Red Sea holds one of the most diverse marine ecosystems in the world, although fragile and vulnerable to ocean warming. Several studies have analysed the spatio-temporal evolution of temperature in the Red Sea using satellite data, thus focusing only on the surface layer and covering the last ∼30 years. To better understand the long-term variability and trends of temperature in the whole water column, we produce a 3-D gridded temperature product (TEMPERSEA) for the period 1958–2017, based on a large number of in situ observations, covering the Red Sea and the Gulf of Aden. After a specific quality control, a mapping algorithm based on optimal interpolation have been applied to homogenize the data. Also, an estimate of the uncertainties of the product has been generated. The calibration of the algorithm and the uncertainty computation has been done through sensitivity experiments based on synthetic data from a realistic numerical simulation. TEMPERSEA has been compared to satellite observations of sea surface temperature for the period 1981–2017, showing good agreement especially in those periods when a reasonable number of observations were available. Also, very good agreement has been found between air temperatures and reconstructed sea temperatures in the upper 100 m for the whole period 1958–2017, enhancing confidence in the quality of the product. The product has been used to characterize the spatio-temporal variability of the temperature field in the Red Sea and the Gulf of Aden at different timescales (seasonal, interannual and multidecadal). Clear differences have been found between the two regions suggesting that the Red Sea variability is mainly driven by air–sea interactions, while in the Gulf of Aden the lateral advection of water plays a relevant role. Regarding long-term evolution, our results show only positive trends above 40 m depth, with maximum trends of 0.045 + 0.016 ∘C decade−1 at 15 m, and the largest negative trends at 125 m (−0.072+0.011 ∘C decade−1). Multidecadal variations have a strong impact on the trend computation and restricting them to the last 30–40 years of data can bias high the trend estimates. ; This research was funded by King Abdullah University of Science and Technology (KAUST) through funds provided to S.A. and C.M.D (BAS/1/1072-01-01). Miguel Agulles has been partly funded by the European Union's Horizon 2020 research and innovation programme under grant agreement no. 776661 (SOCLIMPACT project).

Marbà N, Jordà G, Agusti S, Girard C, Duarte C M. 2015. Footprints of climate change on Mediterranean Sea biota. Frontiers in Marine Science, 2: 00056. DOI=10.3389/fmars.2015.00056 ; The Mediterranean Sea ranks among the ocean regions warming fastest. There is evidence for impacts of climate change on marine Mediterranean organisms but a quantitative assessment is lacking. We compiled the impacts of warming reported in the literature to provide a quantitative assessment for the Mediterranean Sea. During the last three decades the summer surface temperature has increased 1.15°C. Strong heat wave events have occurred in years 1994, 2003, and 2009. Impacts of warming are evident on growth, survival, fertility, migration and phenology of pelagic and benthic organisms, from phytoplankton to marine vegetation, invertebrates and vertebrates. Overall, 50% of biological impacts in the Mediterranean Sea occur at summer surface temperature anomaly ≤ 4.5°C and at summer surface temperature of 27.5°C. The activation energy (geometric mean 1.58 ± 0.48 eV), the slope of the Arrhenius equation describing the temperature-dependence of biological processes, for the response of Mediterranean marine biota to warming reveals that these responses in the Mediterranean are far steepest than possibly explained by the direct effect of warming alone. The observations are biased toward the northern and western sectors of the basin, likely underestimating the impacts of warming in areas where warming is particularly intense. ; This research is a contribution to the ESTRESX (CTM2012-32603) and the CLIMPACT (CGL2014-54246-C2-1-R) projects funded by the Spanish Ministry of Economy and Competitiveness.We thank Xavier Carcelero for assistance during data compilation. GJ also acknowledges a Ramón y Cajal contract (RYC-2013-14714) funded by the Spanish Ministry of Economy and Competitiveness and the Regional Government of theBalearic Islands. ; Peer reviewed

Special issue Polar Microbes.-- 22 pages, 4 figures, 5 tables, supplementary material https://doi.org/10.3390/microorganisms9020317.-- Data Availability Statement: All data is reported in the present article.-- This research is part of POLARCSIC activities ; The ocean surface microlayer (SML), with physicochemical characteristics different from those of subsurface waters (SSW), results in dense and active viral and microbial communities that may favor virus–host interactions. Conversely, wind speed and/or UV radiation could adversely affect virus infection. Furthermore, in polar regions, organic and inorganic nutrient inputs from melting ice may increase microbial activity in the SML. Since the role of viruses in the microbial food web of the SML is poorly understood in polar oceans, we aimed to study the impact of viruses on prokaryotic communities in the SML and in the SSW in Arctic and Antarctic waters. We hypothesized that a higher viral activity in the SML than in the SSW in both polar systems would be observed. We measured viral and prokaryote abundances, virus-mediated mortality on prokaryotes, heterotrophic and phototrophic nanoflagellate abundance, and environmental factors. In both polar zones, we found small differences in environmental factors between the SML and the SSW. In contrast, despite the adverse effect of wind, viral and prokaryote abundances and virus-mediated mortality on prokaryotes were higher in the SML than in the SSW. As a consequence, the higher carbon flux released by lysed cells in the SML than in the SSW would increase the pool of dissolved organic carbon (DOC) and be rapidly used by other prokaryotes to grow (the viral shunt). Thus, our results suggest that viral activity greatly contributes to the functioning of the microbial food web in the SML, which could influence the biogeochemical cycles of the water column ; This research was part of the ATOS project, funded as part of the Spanish contribution to the International Polar Year (IPY) by the Spanish Ministry of Science and Innovation (POL200600550/CTM). J.A.B.'s work was supported by a PhD fellowship from the Spanish Ministerio de Ciencia e Innovación (FPU grant) ; With funding from the Spanish government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S) ; Peer reviewed

The net community production (NCP) of plankton communities affects their role as sources or sinks of atmospheric CO2. Most estimates of NCP have been made by enclosing communities in bottles, generally glass borosilicate, that remove ultraviolet (UV)B and part of UVA wavelengths. A series of experiments were conducted to test whether NCP values from communities incubated excluding UVB (+ part of UVA) radiation (i.e., in glass borosilicate) differ from those of communities receiving the full solar radiation spectrum (i.e., incubated with quartz bottles) and to explore the effect of UV radiation on the respiration rates and bacterial production in these communities. Plankton NCP tended to be 43% lower, on average, when the rates were measured under full solar radiation than when UVB (+ part of UVA) was removed. Dark respiration was significantly enhanced after exposure to the full solar spectrum for most communities, showing lower values when previously incubated in a light environment free of UVB (-50%) or in the dark (-62%). Bacterial production was inhibited by natural sunlight but increased, as observed for community respiration, when transferred to the dark. Communities previously exposed to full solar spectrum showed the greatest increase in bacterial production when allowed to recover in the dark. The net result of these responses were an increase in community respiration and decline in net community production over 24 h, indicating that UVB radiation plays a major role in the metabolic balance of the ocean's surface ecosystem. © 2014, by the Association for the Sciences of Limnology and Oceanography, Inc. ; This study was supported by the Conselleria d'Economía, Hisenda i Inovation, Government of the Balearic Islands to the Grup d'Investigació Competitiu: Grupo de Analisis de Ecosistemas Mediterraneos (GAEM) and by the research projects Evaluacion del Impacto del Cambio Global en Ecosistemas Marinos Mediterraneos (MEDEICG, CTM2009-07013); Remolinos Oceanicos y Deposicion Atmosferica (RODA, CTM2004-06842-C03-02/MAR); Atmospheric inputs of organic carbon and pollutants to the polar ocean: Rates, significance, and Outlook (ATOS, POL2006-00550/CTM), funded by the Spanish Ministry of Science and Innovation; and StressX-Synergia y antagonismo entre multiples estreses en ecosistemas marinos Mediterraneos (CTM2012-32603), funded by the Spanish Ministry of Economy and Competitiveness ; Peer Reviewed

11 pages, 7 figures, 2 tables ; A series of dialysis experiments was performed to study the relative importance of substrate limitation and grazing in controlling the proportion of active cells of coastal marine bacterioplankton. The grazer community was manipulated by filling dialysis bags with unfiltered water and water serially passed through 150-, 40-, and 0.8-μm pore-size filters. The total number of bacteria, the number of metabolically active cells, bacterial loss rates, and the abundances of heterotrophic nanoflagellates were measured immediately and at 3 and 6 d. Gross growth rates were similar in all treatments, suggesting that ambient nutrient concentrations set an upper limit to the maximum growth rates, whereas grazing determined the net growth rates and the final number of bacteria. Bacterial loss rates, measured as the disappearance of fluorescently labeled minicells, correlated well with the initial density of heterotrophic nanoflagellates in the different treatments. The number of active cells at the end of the experiments varied widely among treatments and reached 2.0 x 106 ml-1, or over 55% of the total final density in dialysis bags, with little or no grazing by nanoflagellates. The final proportion of active cells was negatively correlated to both the loss rates and the initial nanoflagellate density, and it was estimated that grazing rates on metabolically active bacteria were four or more times higher than those on inactive bacteria. Heterotrophic nanoflagellates thus seemed to control bacterial density by skimming newly growing cells rather than by cropping the standing stock of bacteria ; This work was supported by grants from the Spanish Interministerial Commission for Science and Technology (CICYT- MAR) and from the Government of Qukbec through the FCAR International Cooperation Program ; Peer Reviewed

An experiment was performed in order to analyze the effects of the increase in water temperature and CO2 partial pressure expected for the end of this century in a present phytoplankton community inhabiting the Arctic Ocean. We analyzed both factors acting independently and together, to test possible interactions between them. The arctic planktonic community was incubated under six different treatments combining three experimental temperatures (1, 6, and 10°C) with two different CO2 levels of 380 or 1000 ppm, at the UNIS installations in Longyearbyen (Svalbard), in summer 2010. Under warmer temperatures, a decrease in chlorophyll a concentration, biovolume and primary production was found, together with a shift in community structure toward a dominance of smaller cells (nano-sized). Effects of increased pCO2 were more modest, and although interactions were weak, our results suggest antagonistic interactive effects amongst increased temperature and CO2 levels, as elevated CO2 compensated partially the decrease in phytoplankton biomass induced by temperature in some groups. Interactions between the two stressors were generally weak, but elevated CO2 was observed to lead to a steeper decline in primary production with warming. Our results also suggest that future increases in water temperature and pCO2 would lead to a decrease in the community chl a concentration and biomass in the Arctic phytoplankton communities examined, leading to communities dominated by smaller nano-phytoplankton groups, with important consequences for the flow of carbon and food web dynamics. ; This study was supported by the project Arctic Tipping Points (ATP, contract # 226248) from the European Union. Alexandra Coello-Camba was supported by a grant BES-2007-15193 from the Spanish Ministry of Science and Innovation. ; Peer reviewed ; Peer Reviewed

11 pages, 4 figures, 3 tables ; Bacterioplankton have the potential to significantly affect the cycling of organic matter in the ocean; however, little is known about the linkage between bacterial assemblage structure and carbon metabolism. In this study, we investigated whether changes in the phylogenetic composition of bacterioplankton were associated with changes in bacterial carbon processing (bacterial production, respiration and biomass) in the subtropical NE Atlantic Ocean. We found consistent differences in the composition of the bacterial assemblage, as revealed by denaturing gradient gel electrophoresis (DGGE) and catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH), along a gradient from the NW African upwelling to the oligotrophic North Atlantic Subtropical Gyre. The percent contribution of Bacteroidetes, Roseobacter and Gammaproteobacteria significantly increased towards more productive waters, whereas the SAR11 clade of the Alphaproteobacteria remained relatively constant (average 28% of DAPI-stained cells) throughout the area. Changes in the composition of the bacterial assemblage detected by DGGE were weakly but significantly correlated with changes in carbon processing variables. The abundances of Roseobacter and Gammaproteobacteria were highly correlated with the concentration of particulate organic carbon and chlorophyll a, reflecting the affinity of these groups to nutrient-enriched conditions. The abundance of Roseobacter was also positively correlated with heterotrophic bacterial production, suggesting their active participation in carbon processing ; Fieldwork was supported by the COCA (REN2000 1471-CO2-O1-MAR) and DEBACOCA (REN2001-4211-E) projects. Molecular work was funded by projects MICRODIFF (REN2001-2120/MAR), BASICS (EVK3-CT- 2002-00078) and GENMUMAR (CTM2004-02586/MAR). This is a contribution to the MARBEF European Network of Excellence (FP6-2002-Global-1). Financial support was provided by a Ph D fellowship from the Spanish government to L.A.S. ; Peer reviewed

The race between pathogens and their hosts is a major evolutionary driver, where both reshuffle their genomes to overcome and reorganize the defenses for infection, respectively. Evolutionary theory helps formulate predictions on the future evolutionary dynamics of SARS-CoV-2, which can be monitored through unprecedented real-time tracking of SARS-CoV-2 population genomics at the global scale. Here we quantify the accelerating evolution of SARS-CoV-2 by tracking the SARS-CoV-2 mutation globally, with a focus on the Receptor Binding Domain (RBD) of the spike protein determining infection success. We estimate that the > 820 million people that had been infected by October 5, 2021, produced up to 1021 copies of the virus, with 12 new effective RBD variants appearing, on average, daily. Doubling of the number of RBD variants every 89 days, followed by selection of the most infective variants challenges our defenses and calls for a shift to anticipatory, rather than reactive tactics involving collaborative global sequencing and vaccination. ; This research was funded by King Abdullah University of Science and technology through research made available to the Computational BioScience Research Center, CMD and TG. TG. VME and JFG acknowledge funding from "la Caixa" Foundation under the project code SR20-00386 (COVID-SHINE). JFG was supported by Direcció General de Política Universitària i Recerca from the government of the Balearic Islands through the postdoctoral program Vicenç Mut. ; Peer reviewed

Measurements of isotopic composition of marine primary producers are a valuable tool to follow and trace the source and cycling of organic matter in the marine systems, as well to describe the physiological status of aquatic photosynthetic organisms. Although stable isotope data abounds in the literature, relatively limited information regarding the isotopic signatures of marine primary producers is available for the Red Sea. Here we present data on carbon concentration (and nitrogen when possible) of phytoplankton, macroalgae, seagrasses, mangroves and salt-marsh plants, and examine how their isotopic signatures differed among plant types across a north-south gradient in the Red Sea. We also tested the potential use of deuterium, δD, to distinguish among primary producers whose carbon isotopic values may overlap. Our findings showed a clear differentiation of carbon and nitrogen content between the different groups of primary producers, as well as between species. Seagrasses and mangroves had on average larger carbon (30 and 49% of C, respectively) and nitrogen content (1.8% N) than other groups. In terms of stable carbon isotopes, seagrasses, and macroalgae tended to be heavier (-7.3 and -13.3%0, respectively) than halophytes, mangroves, and phytoplankton, which showed statistically similar and lighter δC values (between -24 and -26%0). There was a tendency for the nitrogen isotopic composition of seagrass and macroalgae to become lighter from the southern to the northern Red Sea, in parallel to a decline in nitrogen concentration in the tissues, indicative of a higher dependence of nitrogen fixation as a source of nitrogen toward the more oligotrophic northern Red Sea. Our results showed an overlap in the δC and δN values between macroalgae and seagrasses; however, their δD values were significantly different (seagrasses -56.6 ± 2.8%0 and macroalgae -95.7 ± 3.4%0). This remarkable difference offers a promising alternative for ecological studies where a similar range of isotopic values could mask different potential sources. ; This research was funded by King Abdullah University of Science and Technology through base-line funding to CD and SA, with references BAS/1/1071-01-01 and BAS/1/1072-01-01, and CCF funding to CD. IH was supported by a Ramon y Cajal Fellowship RYC2014-14970, cofounded by the Conselleria d'Innovació, Recerca i Turisme of the Balearic Government (Pla de ciència, tecnologia, innovació i emprenedoria 20132017) and the Spanish Ministry of Economy, Industry, and Competitiveness.

13 pages, 5 figures, 3 tables, supplemental material https://www.frontiersin.org/articles/10.3389/fmicb.2019.00494/full#supplementary-material ; Ocean acidification and warming are two main consequences of climate change that can directly affect biological and ecosystem processes in marine habitats. The Arctic Ocean is the region of the world experiencing climate change at the steepest rate compared with other latitudes. Since marine planktonic microorganisms play a key role in the biogeochemical cycles in the ocean it is crucial to simultaneously evaluate the effect of warming and increasing CO2 on marine microbial communities. In 20 L experimental microcosms filled with water from a high-Arctic fjord (Svalbard), we examined changes in phototrophic and heterotrophic microbial abundances and processes [bacterial production (BP) and mortality], and viral activity (lytic and lysogenic) in relation to warming and elevated CO2. The summer microbial plankton community living at 1.4°C in situ temperature, was exposed to increased CO2 concentrations (135–2,318 μatm) in three controlled temperature treatments (1, 6, and 10°C) at the UNIS installations in Longyearbyen (Svalbard), in summer 2010. Results showed that chlorophyll a concentration decreased at increasing temperatures, while BP significantly increased with pCO2 at 6 and 10°C. Lytic viral production was not affected by changes in pCO2 and temperature, while lysogeny increased significantly at increasing levels of pCO2, especially at 10°C (R2 = 0.858, p = 0.02). Moreover, protistan grazing rates showed a positive interaction between pCO2 and temperature. The averaged percentage of bacteria grazed per day was higher (19.56 ± 2.77% d-1) than the averaged percentage of lysed bacteria by virus (7.18 ± 1.50% d-1) for all treatments. Furthermore, the relationship among microbial abundances and processes showed that BP was significantly related to phototrophic pico/nanoflagellate abundance in the 1°C and the 6°C treatments, and BP triggered viral activity, mainly lysogeny at 6 and 10°C, while bacterial mortality rates was significantly related to bacterial abundances at 6°C. Consequently, our experimental results suggested that future increases in water temperature and pCO2 in Arctic waters will produce a decrease of phytoplankton biomass, enhancement of BP and changes in the carbon fluxes within the microbial food web. All these heterotrophic processes will contribute to weakening the CO2 sink capacity of the Arctic plankton community ; This study was funded by the project Arctic Tipping Points (ATP, contract #226248) in the FP7 program of the European Union. EL was supported by a grant from the Spanish Ministry of Science and Innovation ; Peer Reviewed