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The subtropical gyres occupy about 70% of the ocean surface. While primary production (PP) within these oligotrophic regions is relatively low, their extension makes their total contribution to ocean productivity significant. Monitoring marine pelagic primary production across broad spatial scales, particularly across the subtropical gyre regions, is challenging but essential to evaluate the oceanic carbon budget. PP in the ocean can be derived from remote sensing however in situ depth-integrated PP (IPPis) measurements required for validation are scarce from the subtropical gyres. In this study, we collected >120 IPPis measurements from both northern and southern subtropical gyres that we compared to commonly used primary productivity models (the Vertically Generalized Production Model, VGPM and six variants; the Eppley-Square-Root model, ESQRT; the Howard–Yoder–Ryan model, HYR; the model of MARRA, MARRA; and the Carbon-based Production Model, CbPM) to predict remote PP (PPr) in the subtropical regions and explored possibilities for improving PP prediction. Our results showed that satellite-derived PP (IPPsat) estimates obtained from the VGPM1, MARRA and ESQRT provided closer values to the IPPis (i.e., the difference between the mean of the IPPsat and IPPis was closer to 0; |Bias| ~ 0.09). Model performance varied due to differences in satellite predictions of in situ parameters such as chlorophyll a (chl-a) concentration or the optimal assimilation efficiency of the productivity profile (PBopt) in the subtropical region. In general, model performance was better for areas showing higher IPPis, highlighting the challenge of PP prediction in the most oligotrophic areas (i.e. PP

From the beginning of the IEOOS, linked to local oceanographic studies, the IEO has promoted initiatives in order to make them accessible for the wide researcher community and any other users. In 1968 the IEO had designed as National Oceanographic Data Center for safeguarding of marine data and its activities are aimed to favour the quality controlled data and metadata permanent archive and data reusing, as well as the development of aggregated data products

The diel vertical migration (DVM) of zooplankton contributes to the biological pump transporting material from surface to deep waters. We examined the DVM of the zooplankton community in different size fractions (53–200 μm, 200–500 μm, 500–1000 μm, 1000–2000 μm and > 2000 μm) during three cruises carried out in the open NW Mediterranean Sea. We assessed their metabolic rates from empirical published relationships and estimated the active fluxes of dissolved carbon to the mesopelagic zone driven by migrant zooplankton. Within the predominantly oligotrophic Mediterranean Sea, the NW region is one of the most productive ones, with a seasonal cycle characterized by a prominent spring bloom. The study area was visited at three different phases of the seasonal cycle: during the spring bloom, the post-bloom, and strongly stratified oligotrophic conditions. We found seasonal differences in DVM, less evident during the bloom. Changes in DVM intensity were related to the composition of the zooplanktonic assemblage, which also varied between cruises. Euphausiids appeared as the most active migrants in all seasons, and their life cycle conditioned the observed pattern. Immature stages, which are unable to perform large diel vertical movements, dominated during the bloom, in contrast to the higher relative importance of migrating adults in the other two sampling periods. The amount of dissolved carbon exported was determined by the migrant zooplankton biomass, being highest during the post-bloom (2.2 mmol C respired m− 2 d− 1, and up to 3.1 mmol C exported m− 2 d− 1 when DOC release estimations are added). The active transport by diel migrants represented a substantial contribution to total carbon export to deep waters, especially under stratified oligotrophic conditions, revealing the importance of zooplankton in the biological pump operating in the study area., Spanish Ministry of Economy and Competitiveness. Proyecto FAMOSO CTM2008-06261-C03, SI

extended abstract del poster, In order to investigate the role of turbulence mixing on structuring marine phytoplankton communities, the CHAOS project included a multidisciplinary approach involving specifically designed field observations supported by remote sensing, database analyses, and modeling and laboratory chemostat experiments. Field observations carried out in the outer part of Ría de Vigo in summer 2013 showed that, as a result of increased mixing levels, nitrate diffusive input into the euphotic layer was approximately 4-fold higher during spring tides. This nitrate supply could contribute to explain the continuous dominance of large-sized phytoplankton during the upwelling favorable season. Simultaneous estimates of nitrate diffusive fluxes, derived from microturbulence observations, and picoplankton abundance collected in more than 100 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 and picocyanobacteria as a function of changing nutrient supply. The results derived from this project confirm that turbulence and mixing control the availability of light and nutrients, which in turn determine the structure of marine phytoplankton communities., RADIALES-20 (IEO), CHAOS (CTM 2012-30680), Malaspina-2010(CSD2008-00077)

Thematic Issue on Microbiome Ecology.-- 13 pages, 7 figures, 1 table, supporting information https://dx.doi.org/10.1111/1462-2920.13285, Photosynthetic picoeukaryotes (PPEs) are fundamental contributors to oceanic primary production and form diverse communities dominated by prymnesiophytes, chlorophytes, pelagophytes and chrysophytes. Here, we studied the vertical distribution of these major groups in two offshore regions of the northern Iberian Peninsula during summer stratification. We performed a fine-scale vertical sampling (every ∼2 m) across the DCM and used fluorescence in situ hybridization (FISH) to determine the PPE composition and to explore the possible segregation of target groups in the light, nutrient and temperature gradients. Chlorophytes, pelagophytes and prymnesiophytes, in this order of abundance, accounted for the total PPEs recorded by flow cytometry in the Avilés canyon, and for more than half in the Galicia Bank, whereas chrysophytes were undetected. Among the three detected groups, often the prymnesiophytes were dominant in biomass. In general, all groups were present throughout the water column with abundance peaks around the DCM, but their distributions differed: pelagophytes were located deeper than the other two groups, chlorophytes presented two peaks and prymnesiophytes exhibited surface abundances comparable to those at the DCM. This study offers first indications that the vertical distribution of different PPE groups is heterogeneous within the DCM, Financial support has been provided by projects FAMOSO (CTM2008-06261-C03-01/MAR) to ML, MEFISTO (CTM2013-43767-P) to RM and MICRO-3B (FP7-OCEAN-2011 287589, EU). AM Cabello was recipient of a Spanish FPI grant (BES-2009-027194). We are also grateful for the financial support of the Generalitat de Catalunya to the “Grup de Diversitat Microbiana en Ecosistemes Aquàtics” (2014SGR/1591).”

Fluorescent dissolved organic matter (FDOM) in open surface waters (< 200 m) of the Atlantic, Pacific, and Indian oceans was analysed by excitation-emission matrix (EEM) spectroscopy and parallel factor analysis (PARAFAC). A four-component PARAFAC model was fit to the EEMs, which included two humic- (C1 and C2) and two amino acid-like (C3 and C4) components previously identified in ocean waters. Generalized-additive models (GAMs) were used to explore the environmental factors that drive the global distribution of these PARAFAC components. The explained variance for the humic-like components was substantially larger (> 70%) than for the amino acid-like components (< 35%). The environmental variables exhibiting the largest effect on the global distribution of C1 and C2 were apparent oxygen utilisation followed by chlorophyll a. Positive non-linear relationships between both predictor variables and the two humic-like PARAFAC components suggest that their distribution are biologically controlled. Compared with the dark ocean (> 200 m), the relationships of C1 and C2 with AOU indicate a higher C1/AOU and C2/AOU ratios of the humic-like substances in the dark ocean than in the surface ocean where a net effect of photobleaching is also detected. C3 (tryptophan-like) and C4 (tyrosine-like) variability was mostly dictated by salinity (S), by means of positive non-linear relationships, suggesting a primary physical control of their distributions at the global surface ocean scale that could be related to the changing evaporation-precipitation regime. Remarkably, bacterial biomass (BB) only contributed to explain a minor part of the variability of C1 and C4., SI

The 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

Conference communication The 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

Large scale patterns in planktonic food web structure were studied by applying continuous size-scaled models of biomass and δ15N to plankton samples, collected at 145 stations during the Malaspina-2010 Expedition across three ocean basins and including major biomes. Carbon biomass and δ15N were determined in size-fractionated samples (40 to 5000 μm) collected by vertical hauls (0-200 m). Biomass-normalized size-spectra were constructed to summarize food web structure and spatial patterns in spectral parameters were analyzed using geographically-weighted regression analysis. Except in the northwestern Atlantic, size-spectra showed low variability, reflecting a large homogeneity in nitrogen sources and food web structure for the central oceans. Estimated predator-to-prey mass ratios 20% (Trades and Westerlies biomes) suggested that oceanic plankton food webs could support a larger number of trophic levels than current estimates based on high efficiency values. The largest changes in spectral parameters and nitrogen sources were related to inputs of atmospheric nitrogen, either from diazotrophic organisms or dust deposition. These results suggest geographic homogeneity in the net transfer of nitrogen up the food web., CONSOLIDER-INGENIO 2010 (CSD2008-00077) ; EURO-BASIN (FP7-ENV-2010 264933), 1,7490

The effect of internal wave activity on nutrient supply to the euphotic layer and its potential impact on phytoplankton composition and size-structure remain unexplored in the shelf edge off NW Iberian Peninsula. In August 2013, continuous measurements (yo-yo) of dissipation rates of turbulent kinetic energy, obtained with a microstructure profiler, were carried out during spring and neap tides, covering a complete tidal cycle (25 hours). Every hour the yo-yo was interrupted to collect samples for inorganic nutrient concentration. Microturbulence and nutrient concentration data were combined to compute the nutrient input into the euphotic zone driven by vertical diffusivity. Size-fractionated chlorophyll-a and pigment composition samples were taken for the determination of phytoplankton community structure. As a result of increased mixing levels, nitrate transport to the euphotic layer during spring tides was approximately 4-fold higher (34.6 mmol m-2 d-1) than during neap tides (9.4 mmol m-2 d-1). However, the phytoplankton community was always dominated by large (>20 µm) chain-forming diatoms and seemed to be mainly controlled by the upwelling conditions predominating in late August.

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, Spain, The relationships between environmental forcing (hydrographic characteristics of the water column, in situ PAR and major nutrient profiles) and the vertical distribution patterns of in vivo fluorescence and chlorophyll a (Chl a) concentration have been studied along transects of the Malaspina 2010 expedition covering several biogeographic regions in the Indian and Pacific Oceans. Except in the zone of the Equatorial upwelling, a subsurface Chl a maximum (SCM) was generally found at depths between 60 and 150 m. It was typically located at about the 1% light level, in association with the nutriclines and the nitrite maximum. The SCM occurred well below the depth of maximum Brunt-Väisälä frequency in the open Indian Ocean and South Equatorial Pacific, and near or above it in zones strongly influenced by advection (Agulhas, Great Australian Bight). The average proportion of Chl a in the size fraction < 2 micrometers ranged from 60% at surface to 66% at the DCM. The relationship between surface Chl a concentration and integrated Chl a was significant for some geographical regions, but not for the whole data set

Comunicación oral Picoplankton are the most abundant organisms in the ocean, often dominate planktonic biomass and primary production, and they could represent a substantial contribution to the global export of carbon. Nowadays, we have a limited understanding about the factors that control the picoplankton community structure. A recent analysis indicates that light and temperature are the main factors explaining Prochlorococcus and Synechococcus distributions, whereas nutrient concentrations play a minor role (Flombaum et al., PNAS 2013). Methodological difficulties to quantify mixing in the marine enviroments have motivated the use of indirect approaches to determine the input of nutrients into the euphotic zone, however, nutrient concentrations are not necessarily a proxy of nutrient supply. We present a large data set, including open-ocean and coastal regions, of simultaneous measurements of picoplankton abundance, temperature and irradiance, together with estimates of nutrient supply. The transport of nutrients across the nutricline was computed combining nutrient concentrations and small-scale turbulence observations collected with a microstructure profiler. Our preliminary results indicate that nutrient supply also plays a role in the distribution of functional groups of picoplankton in the ocean.

The diel vertical migration (DVM) of zooplankton contributes to the biological pump transporting material from surface to deep waters. We examined the DVM of the zooplankton community in five different size fractions in the open NW Mediterranean Sea. We found differences in DVM at three phases of the seasonal cycle: during the spring bloom, post-bloom, and strongly stratified oligotrophic conditions. DVM intensity was related to the composition of the zooplanktonic assemblage, which also varied between cruises. Euphausiids appeared as the most active migrants in all seasons, and their life cycle conditioned the observed pattern. We estimated active fluxes of dissolved carbon to the mesopelagic zone driven by migrant zooplankton. The amount of dissolved carbon exported was highest during post-bloom conditions (2.2 mmol C respired m-2 d-1, and up to 3.1 mmol C exported m-2 d-1 when DOC release estimations are added). Active transport by diel migrants represented a substantial contribution to total carbon export to deep waters, especially under stratified oligotrophic conditions, revealing the importance of zooplankton in the biological pump operating in the study area.

We used HPLC to test for a differential effect of atmospheric deposition on coastal phytoplankton of Barcelona and Blanes, a neighboring town subjected to a lower anthropogenic aerosol influence. We performed three microcosm experiments: one in winter (in Barcelona) and two in spring (one in Blanes and one in Barcelona). In each experiment, we incubated six containers with 15 L of coastal seawater pre-filtered through 150 μm at the temperature and light cycle of the respective time of the year. We added 0.8 mg L-1 of Saharan dust to two containers, 0.8 mg L-1 of anthropogenic dust to other two, and the remaining were used as controls. Samples for pigment analysis by HPLC were collected at the beginning and at the end of the experiments. In the two experiments from Barcelona, Fucoxantin was always the predominant pigment in both treatments, indicating the dominance of diatoms. However, in Blanes, Zeaxantin predominated initially, indicating the presence of Cyanobacteria, while Fucoxantin, 19’-butanoyloxyfucoxanthin and 19'-hexanoyloxyfucoxanthin, and Chlorophyll-c2 prevailed at the end. We discuss the results from both treatments in relation to the phytoplankton response.

HPLC analysis of phytoplankton pigments from natural samples usually requires the filtration of relatively large volumes of water (1-12 L) through filters of 25-47 mm diameter. Pigment extraction from filters of this size is performed with minimum volumes of 2-5 mL extraction solvent, routinely 90% acetone. The difference in polarity between the solvent for extraction and the initial eluent for HPLC analysis of phytoplankton pigments limits the load to c.a. 150 μL sample into the chromatographic system. This implies that less than 10% of the sample is analyzed, with the consequent decrease of pigment detectability. Here, a procedure allowing injections of up to 1440 μL of 90% acetone without pigment loss is presented. The method can be easily implemented in current HPLC systems. The response of the peak area measured against volume injected was linear (r 2 > 0.998 for any pigment). The precision for injections between 120 and 1440 μL varied between 0.08 and 4.9% (coefficient of variation, n= 4). This system increases the signal response one order of magnitude, reducing the amount of volume filtered and/or enhancing the detectability and identification of minor pigments., Sí

Phytoplankton distribution is relatively constant in large areas of the surface ocean. In order to maintain this apparent stability, phytoplankton production and losses have to be balanced. Indeed, growth (μo) and grazing (g) rates obtained simultaneously with the dilution technique are often tightly coupled. One problem with this approach is that growth and grazing are not independent in the ecological model on which the method is based (net growth rate = μo – g). We evaluated to which extent this methodological artefact may influence the correlation between μo and g estimated using the dilution technique. Following a Monte-Carlo approach, we show that the methodological correlation can be substantial depending on: (1) the % error in the measurement of the state variable ND (e.g. chlorophyll a) and (2) the range (± SD) of the μo and g considered. As long as the error of ND is small (< 10%), the measured correlation between growth and grazing closely reflects a true ecological relationship. For large errors, the dilution technique can yield a substantial correlation between both variables, regardless of their ecological relation. The influence of this methodological correlation decreases as the range of growth and grazing rate values increases. We developed a procedure to evaluate the ecological versus the methodological nature of the correlation observed between μo and g. The application of this procedure to a data set obtained from a coastal site revealed that the high correlation observed (rS = 0.881, p < 0.0001) reflected a true ecological relationship. 2