Assessment of Red Sea temperatures in CMIP5 models for present and future climate

The increase of the temperature in the Red Sea basin due to global warming could have a large negative effect on its marine ecosystem. Consequently, there is a growing interest, from the scientific community and public organizations, in obtaining reliable projections of the Red Sea temperatures throughout the 21st century. However, the main tool used to do climate projections, the global climate models (GCM), may not be well suited for that relatively small region. In this work we assess the skills of the CMIP5 ensemble of GCMs in reproducing different aspects of the Red Sea 3D temperature variability. The results suggest that some of the GCMs are able to reproduce the present variability at large spatial scales with accuracy comparable to medium and high-resolution hindcasts. In general, the skills of the GCMs are better inside the Red Sea than outside, in the Gulf of Aden. Based on their performance, 8 of the original ensemble of 43 GCMs have been selected to project the temperature evolution of the basin. Bearing in mind the GCM limitations, this can be an useful benchmark once the high resolution projections are available. Those models project an averaged warming at the end of the century (2080–2100) of 3.3 ±> 0.6°C and 1.6 ±> 0.4°C at the surface under the scenarios RCP8.5 and RCP4.5, respectively. In the deeper layers the warming is projected to be smaller, reaching 2.2 ±> 0.5°C and 1.5 ±> 0.3°C at 300 m. The projected warming will largely overcome the natural multidecadal variability, which could induce temporary and moderate decrease of the temperatures but not enough to fully counteract it. We have also estimated how the rise of the mean temperature could modify the characteristics of the marine heatwaves in the region. The results show that the average length of the heatwaves would increase ~15 times and the intensity of the heatwaves ~4 times with respect to the present conditions under the scenario RCP8.5 (10 time and 3.6 times, respectively, under scenario RCP4.5).En prensa4,41

Patterns and drivers of UV absorbing chromophoric dissolved organic matter in the euphotic layer of the open ocean

The global distribution of chromophoric dissolved organic matter (CDOM) in the euphotic layer of the Atlantic, Indian, and Pacific oceans (between 35° N and 40° S) was analyzed by absorption spectroscopy during the Malaspina 2010 circumnavigation. Absorption coefficients at 254 nm (a254) and 325 nm (a325), indices (a254/a365) and spectral slopes (between 275 and 295 nm, S275-295) were calculated from the dissolved fraction of the UV absorption spectra to describe the amount and quality of CDOM. Generalized Additive Models (GAMs) were applied to evaluate the relevance of physical and biogeochemical drivers for the variability of CDOM. Besides the low CDOM values, a first division of our data following the Longhurst’s biogeographic classification showed significant differences in CDOM levels among provinces. The lowest values of a254 and a325 were found in the oligotrophic gyres, particularly in the Indian Ocean, and the highest in the upwelling areas, particularly in the Equatorial Pacific. Opposite distributions were obtained for S275-295 and a254/a365, indicative of higher photobleaching in the gyres. Within each province, whereas a254 was constant through the photic layer, a325 increased significantly with depth as a result of the dominance of photobleaching over biological production in the surface layer and the opposite at depth. The Pacific provinces, including the subtropical gyres, showed, however, significantly higher a325 values, indicative of lower photobleaching/higher biological production. The GAM analysis indicates that a254 and a325 were primarily related to chlorophyll a (Chl a), exhibiting a significant positive linear response. Interestingly, Prochlorococcus and Synechococcus abundances were related to these absorption coefficients. Apparent oxygen utilization also contributed to explain the distributions of these absorption coefficients, being inversely related to a254 and directly related to a325. These results are consistent with the premise that a254 could be a proxy for the concentration of dissolved organic carbon and a325 for the aromatic by-products of biological degradation. The GAM analysis also shows that a254/a365 and S275-295 exhibited inverse relationships with solar radiation, indicating that the biological production of CDOM counteracts photodegradation as solar radiation increases. In summary, whereas photobleaching dictates the vertical distribution of CDOM, Chl a explains the CDOM differences among the photic layer of the tropical and subtropical ocean provinces visited during the circumnavigationMinisterio de Economía y Competitividad | Ref. CDS2008-0007

A comparative study of responses in planktonic food web structure and function in contrasting European coastal waters exposed to experimental nutrient addition

We quantify, compare, and generalize responses of experimental nutrient loadings (LN) on planktonic community structure and function in coastal waters. Data were derived from three mesocosm experiments undertaken in Baltic (BAL), Mediterranean (MED), and Norwegian (NOR) coastal waters. A planktonic model with seven functional compartments and 30-32 different carbon flows fit to all three experiments was used as a framework for flow-rate estimation and comparison. Flows were estimated on the basis of time series of measured biomass, some measured flows, and inverse modeling. Biomass and gross uptake rate of carbon of most groups increased linearly with increasing LN in the nutrient input range of 0-1 µmol N L-1 d-1 at all locations. The fate of the gross primary production (GPP) was similar in all systems. Autotrophic biomass varied by two orders of magnitude among locations, with the lowest biomass and response to nutrient addition in MED waters. The variation of GPP among sites was less than one order of magnitude. Mesozooplankton dominated by doliolids (Tunicata), but not those dominated by copepods, presumably exerted efficient control of the autotrophic biomass, thereby buffering responses of autotrophs to high nutrient input. Among the many factors that can modify the responses of autotrophs to nutrients, the time scale over which the enrichment is made and the precise mode of nutrient enrichment are important. We suggest a general concept that may contribute to a scientific basis for understanding and managing coastal eutrophicatio

Nutrient supply does play a role on the structure of marine picophytoplankton communities

Conference communicationThe Margalef´s mandala (1978) is a simplified bottom-up control model that explains how mixing and nutrient concentration determine the composition of marine phytoplankton communities. Due to the difficulties of measuring turbulence in the field, previous attempts to verify this model have applied different proxies for nutrient supply, and very often used interchangeably the terms mixing and stratification. Moreover, because the mandala was conceived before the discovery of smaller phytoplankton groups (picoplankton <2 µm), it describes only the succession of vegetative phases of microplankton. In order to test the applicability of the classical mandala to picoplankton groups, we used a multidisciplinary approach including specifically designed field observations supported by remote sensing, database analyses, and modeling and laboratory chemostat experiments. Simultaneous estimates of nitrate diffusive fluxes, derived from microturbulence observations, and picoplankton abundance collected in more than 200 stations, spanning widely different hydrographic regimes, showed that the contribution of eukaryotes to picoautotrophic biomass increases with nutrient supply, whereas that of picocyanobacteria shows the opposite trend. These findings were supported by laboratory and modeling chemostat experiments that reproduced the competitive dynamics between picoeukaryote sand picocyanobacteria as a function of changing nutrient supply. Our results indicate that nutrient supply controls the distribution of picoplankton functional groups in the ocean, further supporting the model proposed by Margalef.Spanish Governmen

Global beta diversity patterns of microbial communities in the surface and deep ocean

This is contribution 1112 from AZTI Marine Research Division.-- 14 pages, 4 figures, 3 tables, supporting information https://doi.org/10.1111/geb.13572.-- Data Availability Statement: DNA sequences for surface prokaryotes are publicly available at the European Nucleotide Archive [http://www.ebi.ac.uk/ena; accession number PRJEB25224 (16S rRNA genes)], for deep prokaryotes at the National Center for Biotechnology Information (NCBI) Sequence Read Archive (http://www.ncbi.nlm.nih.gov/Traces/sra) under accession ID SRP031469, and for surface and deep picoeukaryotes at the European Nucleotide Archive with accession number PRJEB23771 (http://www.ebi.ac.uk/ena). Environmental data used in this study are available from https://github.com/ramalok/malaspina.surface.metabacoding, Giner et al. (2020) and Salazar et al. (2015). The code to analyze the data and produce the figures of this research is available from the corresponding author upon request.-- This is the pre-peer reviewed version of the following article: Ernesto Villarino, James R. Watson, Guillem Chust ,A. John Woodill, Benjamin Klempay, Bror Jonsson, Josep M. Gasol, Ramiro Logares, Ramon Massana, Caterina R. Giner, Guillem Salazar, X. Anton Alvarez-Salgado, Teresa S. Catala, Carlos M. Duarte, Susana Agusti, Francisco Mauro, Xabier Irigoien, Andrew D. Barton; Global beta diversity patterns of microbial communities in the surface and deep ocean; Global Ecology and Biogeography 31(11): 2323-2336 (2022), which has been published in final form at https://doi.org/10.1111/geb.13572. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsAim: Dispersal and environmental gradients shape marine microbial communities, yet the relative importance of these factors across taxa with distinct sizes and dispersal capacity in different ocean layers is unknown. Here, we report a comparative analysis of surface and deep ocean microbial beta diversity and examine how these patterns are tied to oceanic distance and environmental gradients. Location: Tropical and subtropical oceans (30°N–40°S). Time period: 2010-2011. Major taxa studied: Prokaryotes and picoeukaryotes (eukaryotes between 0.2 and 3 μm). Methods: Beta diversity was calculated from metabarcoding data on prokaryotic and picoeukaryotic microbes collected during the Malaspina expedition across the tropical and subtropical oceans. Mantel correlations were used to determine the relative contribution of environment and oceanic distance driving community beta diversity. Results: Mean community similarity across all sites for prokaryotes was 38.9% in the surface and 51.4% in the deep ocean, compared to mean similarity of 25.8 and 12.1% in the surface and deep ocean, respectively, for picoeukaryotes. Higher dispersal rates and smaller body sizes of prokaryotes relative to picoeukaryotes likely contributed to the significantly higher community similarity for prokaryotes compared with picoeukaryotes. The ecological mechanisms determining the biogeography of microbes varied across depth. In the surface ocean, the environmental differences in space were a more important factor driving microbial distribution compared with the oceanic distance, defined as the shortest path between two sites avoiding land. In the deep ocean, picoeukaryote communities were slightly more structured by the oceanic distance, while prokaryotes were shaped by the combined action of oceanic distance and environmental filtering. Main conclusions: Horizontal gradients in microbial community assembly differed across ocean depths, as did mechanisms shaping them. In the deep ocean, the oceanic distance and environment played significant roles driving microbial spatial distribution, while in the surface the influence of the environment was stronger than oceanic distanceData collection was funded by the Malaspina 2010 Circumnavigation Expedition project (Consolider-Ingenio 2010, CSD2008-00077) and cofunded by the Basque Government (Department Deputy of Agriculture, Fishing and Food Policy). We acknowledge funding from the Spanish Government through the “Severo Ochoa Center of Excelence” accreditation CEX2019-000928-S. [...] We also acknowledge H2020 Mission Atlantic project (Ref. Grant Agreement Number 862428). EV was supported by an international exchange post-doc scholarship to Scripps Institution of Oceanography and Oregon State University granted by the Education Department of the Basque GovernmentPeer reviewe

Large carbon export, but short residence times, of transparent exopolymer particles in the global ocean

ASLO Aquatic Sciences Meeting 2023, Resilience and Recovery in Aquatic Systems, 4–9 June 2023, Palma de Mallorca, SpainAcidic polysaccharides released by phytoplankton and prokaryotic heterotrophs promote the formation of gel-like transparent exopolymer particles (TEPs). TEPs can have a relevant contribution to the biological carbon pump due to their carbon-rich composition and their ability to coagulate and sink towards the deep ocean. However, little is known about TEPs distribution, carbon export, and residence times below the export (200 m) and sequestration (1000 m) depths. We provide the first comprehensive inventory of TEP from the ocean surface to a depth of 4000 meters in the tropical and subtropical Atlantic, Indian, and Pacific Oceans, evaluating its contribution to carbon export and sequestration into the deep ocean. Results indicate that TEP concentration is primarily determined by primary production, with higher concentrations located above the deep chlorophyll maxima. In the deep ocean, TEP concentrations are lower yet mirror the concentrations in the surface, demonstrating the significance of TEP sinking below both the export compartment (2.8 Pg C yr-1; 27% of total POC flux at 200 m) and the sequestration compartment (0.8 Pg C yr-1; 36% of total POC flux at 1000 m). In situ incubation experiments conducted across ocean basins indicate short TEP residence times, averaging 27 and 333 days in the export and sequestration compartments, respectively. These findings reveal that the export and subsequent sequestration of carbon by TEP sinking into the deep ocean diverts it from the long times observed for the dissolved carbon fraction (i.e. centuries) in the global carbon cycleN

A Systems Biology Approach Identifies Molecular Networks Defining Skeletal Muscle Abnormalities in Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) is an inflammatory process of the lung inducing persistent airflow limitation. Extensive systemic effects, such as skeletal muscle dysfunction, often characterize these patients and severely limit life expectancy. Despite considerable research efforts, the molecular basis of muscle degeneration in COPD is still a matter of intense debate. In this study, we have applied a network biology approach to model the relationship between muscle molecular and physiological response to training and systemic inflammatory mediators. Our model shows that failure to co-ordinately activate expression of several tissue remodelling and bioenergetics pathways is a specific landmark of COPD diseased muscles. Our findings also suggest that this phenomenon may be linked to an abnormal expression of a number of histone modifiers, which we discovered correlate with oxygen utilization. These observations raised the interesting possibility that cell hypoxia may be a key factor driving skeletal muscle degeneration in COPD patients

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Growth and abundance of Synechococcus sp. in a Mediterranean Bay: Seasonality and relationship with temperature

Este artículo contiene 9 páginas, 5 figuras.In this study, we confirm the relationship between temperature and Synechococcus sp. experimental growth rates (r = 0.87, p < 0.005) and provide evidence of the existence of a general relationship. This link leads to a strong seasonality of abundance and biomass of Synechococcus sp. in the Bay of Blanes (NW Mediterranean), which was followed for 2 yr (1995, 1996), with high values in summer months (6 X 10' cells I-') and low values in winter (5 X 105 cells I-'). The growth rate achieved in summer months (1.5 d-') IS close to or at the maximum possible at the in situ water temperature. As a result, Synechococcus growth may exceed the grazing capacity of its predators in summer, and this explains its significant contribution of >30%, of the total gross autotrophic production and >20% of the total autotroph~cb lomass in summer Thus, Sj~nechococcusis an important source of organic C and nutrients for the coastal Mediterranean food web in the summer.This study was funded by the European Commission under the MAST programme (contract MAS3- CT96-0045) and by the Spanish Commission of Science and Technology (CICYT project AMB94-0746). N.S.R.A. is supported by a fellowship of the Agencia Espaliola de Cooperacion InternacPeer reviewe

Prochlorococcus and synechococcus cells in the central Atlantic Ocean: Distribution, growth and mortality (grazing) rates

The distribution, primary production, growth and grazing rates of Prochlorococcus and Synechococcus were investigated across the tropical Atlantic ocean during boreal autumn and spring. The picophytoplankton fraction contributed significantly to total phytoplankton community biomass and production (>70% and > 50%, respectively). Prochlorococcus reaching up to 2.5 · 105 cells ml-1 numerically dominated the picophytoplankton community in the central oligotrophic Atlantic waters while Synechococcus was abundant at the ends of the transects (i.e. in nutrient rich coastal waters). High resolution surface samples showed the meridional patterns of Prochlorococcus and Synechococcus abundance to be highly variable within a few degrees latitude and correlated well with intermediate scale variability (< 500 km) in water mass structure along the transects. Growth rates of Prochlorococcus and Synechococcus in surface waters range from 0.40 to 1.47 d-1, and 0.22 to 1.58 d-1, respectively. There was a positive relationship (r=0.77, p<0.05) between growth and grazing rates, and the average differences between growth and grazing rates were -0.17 ± 0.25 d-1, and 0.15 ± 0.11 d-1, for Prochlorococcus and Synechococcus, respectively. High grazing rates on Prochlorococcus and Synechococcus indicate that top down control of picophytoplankton abundance is most likely important in Central Atlantic waters.Peer Reviewe