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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)

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

El Gergal is the last link in a system of reservoirs located in the Rivera de Huelva River, Seville (South-West Spain). Because of its position within the system and the different water transfer possibilities between reservoirs, the florisitic composition of phytoplankton in El Gergal can be strongly influenced by the concentration of cells present in the water transferred from other reservoirs in the series. In June 2000 a large Ceratium hirundinella inoculums was transferred from an upstream reservoir into El Gergal. The dinoflagellate inoculums entered in the receiving reservoir through the riverine zone depicting a marked horizontal structure, and inducing an intense summer bloom. Our results show that this Ceratium bloom was effective to compete and counteract the later development of the harmful cyanobacteria Aphanizomenon flos-aquae. Further, after the integration of a set of adaptations to the semi-arid Mediterranean region and subsequently validation, the PROTECH model (a 1D phytoplankton community model) was used to describe, assess and evaluate the potential impact on El Gergal phytoplankton dynamics of an alternative water transfer strategy. Finally, we encourage the use of dynamic modelling in lakes and reservoir management, as it constitutes a powerful tool that should offer reliable predictions and help managers in the usually difficult and complex task of adopting optimal decisions, in order to minimise water treatment costs and provide the best possible environmental quality. El Gergal ocupa la última posición dentro de la cadena de embalses ubicada sobre el río Rivera de Huelva (Sevilla, Sureste de España). Debido a su singular localización, El Gergal constituye el último receptor de una amplia gama de estrategias de trasvase de aguas. Como consecuencia, su comunidad fitoplanctónica presenta una dinámica espacio-temporal frecuentemente influida por la composición y la abundancia de microalgas en las aguas de trasvase. De esta manera, en junio de 2000 un trasvase de aguas desde el embalse de La Minilla a El Gergal propició el ingreso en éste de un importante inóculo del dinoflagelado Ceratium hirundinella a través de su zona fluvial. Una vez en El Gergal, Ceratium generó una marcada estructura horizontal y su población registró una intensa proliferación estival. Nuestros resultados sugieren que dicha proliferación de dinoflagelados repercutió de forma negativa en el posterior desarrollo de la cianobacteria Aphanizomenon flos-aquae. Además, tras la integración y validación de una serie de adaptaciones específicas para ecosistemas leníticos Mediterráneos, se aplicó el modelo numérico unidimensional de comunidad fitoplanctónica PROTECH para describir y evaluar el impacto potencial sobre la dinámica fitoplanctónica de El Gergal de una estrategia alternativa de trasvase de aguas. En este contexto, sugerimos el uso de modelos dinámicos como herramientas eficientes en la gestión integrada de embalses. Sin duda, su aplicación resultará de utilidad en la difícil y compleja tarea que supone adoptar decisiones que combinen la optimización de los costes de tratamiento del agua con el mantenimiento de una calidad ecológica adecuada.

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 hydrodynamic behaviour in lentic ecosystems is closely related with the spatial and temporal evolution of their physical, chemical and biological characteristics. Because of this, and in order to improve our present knowledge on the limnological dynamics of such ecosystems, a coupled analysis on the relationship between the biological patterns and the governing hydrodynamics mechanisms it is necessary. This paper uses both field analysis and numerical simulation to describe the links between the water movements and the phytoplankton spatial distribution on two shallow waterbodies in the South of Spain: Alhama de Granada Reservoir (Granada) and Laguna Nueva de la Albufera de Adra (Almería). In both systems the observed phytoplankton spatial distribution exhibited dynamic patterns forced by hydrodynamical transport processes. The knowledge of this physical-biological coupling could be useful to outline the basic guidelines for water quality management. Los ecosistemas acuáticos leníticos se caracterizan por un intenso acoplamiento entre los mecanismos de transporte hidrodinámico que en ellos ocurren y la evolución espacial y temporal de sus principales variables físico-químicas y biológicas. En consecuencia y con el objetivo de mejorar nuestro entendimiento sobre la dinámica limnológica de este tipo de sistemas, resulta necesario el desarrollo de análisis interdisciplinares que profundicen en esta estrecha relación hidrodinámica-biología. En este trabajo se analiza, a partir de estudios de campo y simulaciones numéricas, el acoplamiento entre el movimiento de la masa fluida a nivel de macroescala y la distribución espacial del fitoplancton en dos ecosistemas acuáticos someros del Sur de España : el embalse de Alhama de Granada (Granada) y la Laguna Nueva de la Albufera de Adra (Almería). En ambos sistemas se han encontrado patrones dinámicos de distribución espacial de las microalgas, íntimamente relacionados con la dinámica de la masa de agua. El conocimiento de este acoplamiento resulta útil en la definición de líneas básicas para la adecuada gestión de la calidad del agua.

The latitudinal position of the north-wall of the Gulf Stream influences the climatic conditions in the Atlantic North and Western Europe. Southerly movements of the Gulf Stream (low Gulf Stream Index values, GSI) typically induce unstable meteorological conditions in this region, while north displacements of the oceanic current (high GSI values) are associated with stable weather. In the present article we explore a seven years data set including annual GSI, meteorological records and phytoplankton community composition and abundance to demonstrate that the year-to-year changes in the position of the Gulf Stream and its influence on the prevailing weather conditions have an effect on the long-term variability of phytoplankton community in El Gergal reservoir, an ecosystem located in the Atlantic coast of Andalusia (SW Spain). Furthermore, we describe the response of each considered phytoplankton functional groups to changes in the Gulf Stream position. Thus, northerly displacements of the north-wall increased the abundance of H+S1 cyanobacteria through a non-linear function with two marked GSI thresholds. GSI and Lm dinoflagellates abundance depicted a significant positive linear correlation, while groups B + P diatoms abundance was negatively linear correlated with GSI. Groups Y cryptophytes and X1 + J chlorophytes abundance remained nearly constant for most of the studied years but developed an exponential increase at high GSI years. Implications for water quality management are pointed out. Las condiciones climáticas en la fachada Atlántica europea están influidas por las variaciones temporales en la posición latitudinal de la Corriente del Golfo en el océano Atlántico. Así, el desplazamiento hacia el Sur de la Corriente del Golfo (valores bajos del Índice de la Corriente del Golfo, GSI) induce condiciones de inestabilidad meteorológica en la Europa occidental, mientras que los desplazamientos septentrionales de la corriente oceánica (elevados valores del GSI) están asociados con mayor estabilidad meteorológica en esta región. Este artículo estudia la influencia de los cambios interanuales en la posición de la Corriente del Golfo sobre la comunidad fitoplanctónica del embalse de El Gergal, un ecosistema localizado en la costa atlántica andaluza (SW España). Para ello, a lo largo de siete años se han registrado valores anuales de GSI, información meteorológica y datos sobre la composición y biovolumen del fitoplancton. El análisis de esta información permite describir cómo las variaciones anuales en la posición de la Corriente del Golfo afectan a las condiciones meteorológicas en el área de estudio, influyendo de esta manera sobre el biovolumen de cada uno de los grupos funcionales de fitoplancton considerados. Los desplazamientos hacia el Norte de la Corriente del Golfo favorecieron el incremento del biovolumen de cianobacterias de los grupos H + S1 a través de una función no lineal con dos valores críticos de GSI bien definidos. Por su parte, se encontró una relación lineal positiva entre el GSI y el biovolumen de dinoflagelados del grupo Lm, mientras que las diatomeas de los grupos B + P se relacionaron de forma inversa con el GSI. Aunque el biovolumen de clorofitas de los grupos X1 + J y de criptofitas del grupo Y permaneció estable durante la mayor parte de los años estudiados, se registró un notable incremento del mismo en aquellos años en los que el GSI mostró sus valores más elevados. Finalmente se apuntan algunas consideraciones sobre posibles implicaciones en la gestión de la calidad del agua embalsada.

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Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. © 2018 by the authors. Licensee MDPI, Basel, Switzerland., The authors acknowledge COST Action ES 1105 “CYANOCOST—Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE—Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from the University of Geneva. We thank Clare Ahnlund, Ena Suarez and Irene Gallego for helping out with the Swiss survey. We thank Wendy Beekman and Els J. Faassen for the nutrient and toxin analysis.

Under ongoing climate change and increasing anthropogenic activity, which continuously challenge ecosystem resilience, an in-depth understanding of ecological processes is urgently needed. Lakes, as providers of numerous ecosystem services, face multiple stressors that threaten their functioning. Harmful cyanobacterial blooms are a persistent problem resulting from nutrient pollution and climate-change induced stressors, like poor transparency, increased water temperature and enhanced stratification. Consistency in data collection and analysis methods is necessary to achieve fully comparable datasets and for statistical validity, avoiding issues linked to disparate data sources. The European Multi Lake Survey (EMLS) in summer 2015 was an initiative among scientists from 27 countries to collect and analyse lake physical, chemical and biological variables in a fully standardized manner. This database includes in-situ lake variables along with nutrient, pigment and cyanotoxin data of 369 lakes in Europe, which were centrally analysed in dedicated laboratories. Publishing the EMLS methods and dataset might inspire similar initiatives to study across large geographic areas that will contribute to better understanding lake responses in a changing environment.

Book chapter, Protocolo de recogida y conservación de muestras de agua para el aná lisis simultáneo de carbono orgánico total (TOC) y nitrógeno total (TN) por el método de oxidación catalítica a alta temperatura, Gobierno de España, CSIC, Fundación BBVA, Acción Cultural Española

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Book chapter, Protocolo de recogida de muestras de agua para el análisis de la absor bancia y fluorescencia de la materia orgánica cromófora y su determina ción a bordo por espectrofotometría y espectrofluorimetría., Gobierno de España, CSIC, Fundación BBVA

Book chapter, Metodología para obtener muestras de materia orgánica particulada (POM) y disuelta ultrafiltrada (UDOM o HMW), o de alto peso molecular, en aguas profundas, Gobierno de España, CSIC, Fundación BBVA

9 pages.