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O control da turbulencia na dinámica de suministro de nutrientes sobre a estrutura das comunidades de picoplancto mariño
'Japanese Society of Applied Entomology & Zoology', 2021Co-Authors: Otero-ferrer, Jose LuisAbstract:Memoria de tesis doctoral presentada por Jose Luís Otero-Ferrer para obtener el título de Doctor en Ciencias Mariñas, Tecnoloxía e Xestión por la Universida de Vigo, realizada bajo la dirección de la Dra. Beatriz Mouriño Carballido de la Universida de Vigo y el Dr. Pedro Cermeño Aínsa del Institut de Ciències del Mar (ICM-CSIC).-- 167 pages, figures, tables[EN] Oligotrophic regions are characterized by a shortage of nutrients in surface waters, with nitrogen being the main limiting nutrient in most tropical and subtropical regions of the open ocean, as well as in temperate and polar seas during periods of seasonal stratification. Since some of the biological production in the photic layer is exported to the deep ocean (export), the maintenance of biological production will depend on the input of nutrients into the system. Mechanisms contributing to new production include biological nitrogen fixation, atmospheric deposition, and diffusive and advective vertical and horizontal transport of organic and inorganic forms of nitrogen. Calculation of vertical diffusive transport requires estimation of diffusivity (Kz). The methodological difficulties in obtaining Kz estimates led to the use of constant Kz values, and empirical parameterizations of vertical diffusivity. However, the commercialization of microstructure turbulence profilers has facilitated the obtaining of microstructure turbulence observations, which revealed an important Kz variability in the upper layer. Alternatively, the concentration of dissolved inorganic nutrients in the photic layer has been used as an estimator of nutrient availability to planktonic communities. However, under steady-state conditions, such as subtropical gyres, where nutrient supply by diffusion into the euphotic zone is slow, there may be no relationship between nutrient concentration in the photic layer and nutrient supply. The Picoplankton refers to the fraction of plankton smaller than 2 µm and consists of Synechococcus, picoeukaryotes, Prochlorococcus and heterotrophic bacteria. The latter can be divided into bacteria with high (HNA) or low (LNA) nucleic acid content. Photosynthetic Picoplankton generally dominate biomass and primary production in tropical and subtropical oligotrophic regions, while their contribution is less in nutrient-rich coastal regions. In marine ecosystems, a major source of environmental heterogeneity lies in the temporal fluctuation of nutrient supplies, which controls the diversity of the phytoplankton community. Under steady state conditions, the minimum level of resources that can sustain a population determines competition. Experimental studies and numerical models of competition support this theoretical basis for large phytoplankton. While numerous studies have investigated the effect of nutrient supply dynamics on interspecific competition of large phytoplankton species, their effect on the groups that make up phytoplankton has received much less attention. The main hypothesis of this thesis is that the dynamics of nutrient supply controls the composition of marine Picoplankton communities. To achieve this goal, a multidisciplinary approach will be used, combining field observations made during 17 oceanographic campaigns in the Atlantic, Pacific and Indian tropical and subtropical oceans, the Northwest Mediterranean Sea, the Galician coastal upwelling ecosystem and the Antarctic Peninsula with laboratory experiments and ecological modeling of competitive interactions[ES] Las regiones oligotróficas se caracterizan por una escasez de nutrientes en aguas superficiales, siendo el nitrógeno el principal nutriente limitante en la mayor parte de las regiones tropicales y subtropicales del océano abierto, así como en mares templados y polares durante períodos de estratificación estacional. Dado que una parte de la producción biológica en la capa fótica se exporta cara el océano profundo (exportación), el mantenimiento de la producción biológica dependerá de la entrada de nutrientes al sistema. Los mecanismos que contribuyen a la nueva producción incluyen la fijación biológica del nitrógeno, la deposición atmosférica y el transporte vertical y horizontal difusivo y advectivo de formas orgánicas e inorgánicas de nitrógeno. El cálculo del transporte difusivo vertical requiere de la estimación de la difusividad (Kz). Las dificultades metodológicas en la obtención de estimas de Kz motivaron la utilización de valores constantes de Kz, y parametrizaciones empíricas de difusividad vertical. Sin embargo, la comercialización de los perfiladores de turbulencia de microestructura ha facilitado la obtención de observaciones de turbulencia de microstructura, que revelaron una importante variabilidad de Kz en la capa superior. Alternativamente se ha utilizado la concentración de nutrientes inorgánicos disueltos en la capa fótica como un estimador de la disponibilidad de nutrientes para las comunidades planctónicas. Sin embargo, en condiciones de estado estacionario, como los giros subtropicales, donde el suministro de nutrientes por difusión hacia la zona eufótica es lento puede no existir relación entre la concentración de nutrientes en la capa fótica y su suministro. El picoplancton hace referencia a la fracción del plancton menor de 2 µm y está constituido por Synechococcus, picoeukaryotes, Prochlorococcus y bacterias heterótrofas. Estas últimas se pueden dividir entre bacterias con alto (HNA) o bajo (LNA) contenido en acidos nucleicos. Generalmente el picoplancton fotosintético domina la biomasa y la producción primaria en regiones oligotróficas tropicales y subtropicales, mientras que su contribución es menor en regiones costeras ricas en nutrientes. En los ecosistemas marinos, una fuente importante de heterogeneidad ambiental radica en la fluctuación temporal del suministros de nutrientes, que controla la diversidad de la comunidad de fitoplancton. En condiciones de estado estacionario, el nivel mínimo de recursos que puede sostener una población determina la competencia. Estudios experimentales y modelos numéricos de competición apoyan esta base teórica para el fitoplancton de gran tamaño. Mientras que numerosos estudios han investigado el efecto de la dinámica del suministro de nutrientes sobre la competencia interespecífica de especies de fitoplancton de gran tamaño, su efecto sobre los grupos que componen el picofitoplancton ha recibido mucha menos atención. La hipótesis principal de esta tesis es que la dinámica del suministro de nutrientes controla la composición de las comunidades de picoplancton marino. Para lograr este objetivo, se utilizará un enfoque multidisciplinar, combinando observaciones de campo realizadas durante 17 campañas oceanográficos realizadas en los océanos Atlántico, Pacífico e Índico tropicales y subtropicales, el Mar Mediterráneo Noroccidental, el ecosistema de afloramiento costero gallego y la Peninsula Antártica con experimentos de laboratorio y modelado ecológico de interacciones competitivas[GA] As rexións oligotróficas caracterízanse por unha escaseza de nutrientes en augas superficiais, sendo o nitróxeno o principal nutriente limitante na maior parte das rexións tropicais e subtropicales do océano aberto, así como en mares tépedos e polares durante períodos de estratificación estacional. Dado que unha parte da produción biolóxica na capa fótica expórtase cara o océano profundo (exportación), o mantemento da produción biolóxica dependerá da entrada de nutrientes ao sistema. Os mecanismos que contribúen á nova produción inclúen a fixación biolóxica do nitróxeno, a deposición atmosférica e o transporte vertical e horizontal difusivo e advectivo de formas orgánicas e inorgánicas de nitróxeno. O cálculo do transporte difusivo vertical require da estimación da difusividad ( Kz). As dificultades metodolóxicas na obtención de estimas de Kz motivaron a utilización de valores constantes de Kz, e parametrizacións empíricas de difusividad vertical. Con todo, a comercialización dos perfiladores de turbulencia de microestructura facilitou a obtención de observacións de turbulencia de microstructura, que revelaron unha importante variabilidade de Kz na capa superior. Alternativamente utilizouse a concentración de nutrientes inorgánicos disoltos na capa fótica como un estimador da dispoñibilidade de nutrientes para as comunidades planctónicas. Con todo, en condicións de estado estacionario, como os xiros subtropicales, onde a subministración de nutrientes por difusión cara á zona eufótica é lento pode non existir relación entre a concentración de nutrientes na capa fótica e a súa subministración. O picoplancton fai referencia á fracción do plancto menor de 2 µ m e está constituído por Synechococcus, picoeukaryotes, Prochlorococcus e bacterias heterótrofas. Estas últimas pódense dividir entre bacterias con alto ( HNA) ou baixo ( LNA) contido en acidos nucleicos. Xeralmente o picoplancton fotosintético domina a biomasa e a produción primaria en rexións oligotróficas tropicais e subtropicales, mentres que a súa contribución é menor en rexións costeiras ricas en nutrientes. Nos ecosistemas mariños, unha fonte importante de heteroxeneidade ambiental radica na fluctuación temporal do subministracións de nutrientes, que controla a diversidade da comunidade de fitoplancto. En condicións de estado estacionario, o nivel mínimo de recursos que pode soster unha poboación determina a competencia. Estudos experimentais e modelos numéricos de competición apoian esta base teórica para o fitoplancto de gran tamaño. Mentres que numerosos estudos investigaron o efecto da dinámica da subministración de nutrientes sobre a competencia interespecífica de especies de fitoplancto de gran tamaño, o seu efecto sobre os grupos que compoñen o picofitoplancton recibiu moita menos atención. A hipótese principal desta tese é que a dinámica da subministración de nutrientes controla a composición das comunidades de picoplancton mariño. Para lograr este obxectivo, utilizarase un enfoque multidisciplinar, combinando observacións de campo realizadas durante 17 campañas oceanográficos realizadas nos océanos Atlántico, Pacífico e Índico tropicais e subtropicales, o Mar Mediterráneo Noroccidental, o ecosistema de afloramiento costeiro galego e a Península Antártica con experimentos de laboratorio e modelado ecolóxico de interaccións competitiva
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O control da turbulencia na dinámica de suministro de nutrientes sobre a estrutura das comunidades de picoplancto mariño
Programa de Doutoramento en Ciencias Mariñas Tecnoloxía e Xestión (RD 99 2011), 2020Co-Authors: Otero-ferrer, Jose LuisAbstract:Oligotrophic regions are characterized by a shortage of nutrients in surface waters, with nitrogen being the main limiting nutrient in most tropical and subtropical regions of the open ocean, as well as in temperate and polar seas during periods of seasonal stratification. Since some of the biological production in the photic layer is exported to the deep ocean (export), the maintenance of biological production will depend on the input of nutrients into the system. Mechanisms contributing to new production include biological nitrogen fixation, atmospheric deposition, and diffusive and advective vertical and horizontal transport of organic and inorganic forms of nitrogen. Calculation of vertical diffusive transport requires estimation of diffusivity (Kz). The methodological difficulties in obtaining Kz estimates led to the use of constant Kz values, and empirical parameterizations of vertical diffusivity. However, the commercialization of microstructure turbulence profilers has facilitated the obtaining of microstructure turbulence observations, which revealed an important Kz variability in the upper layer. Alternatively, the concentration of dissolved inorganic nutrients in the photic layer has been used as an estimator of nutrient availability to planktonic communities. However, under steady-state conditions, such as subtropical gyres, where nutrient supply by diffusion into the euphotic zone is slow, there may be no relationship between nutrient concentration in the photic layer and nutrient supply. The Picoplankton refers to the fraction of plankton smaller than 2 µm and consists of Synechococcus, picoeukaryotes, Prochlorococcus and heterotrophic bacteria. The latter can be divided into bacteria with high (HNA) or low (LNA) nucleic acid content. Photosynthetic Picoplankton generally dominate biomass and primary production in tropical and subtropical oligotrophic regions, while their contribution is less in nutrient-rich coastal regions. In marine ecosystems, a major source of environmental heterogeneity lies in the temporal fluctuation of nutrient supplies, which controls the diversity of the phytoplankton community. Under steady state conditions, the minimum level of resources that can sustain a population determines competition. Experimental studies and numerical models of competition support this theoretical basis for large phytoplankton. While numerous studies have investigated the effect of nutrient supply dynamics on interspecific competition of large phytoplankton species, their effect on the groups that make up phytoplankton has received much less attention. The main hypothesis of this thesis is that the dynamics of nutrient supply controls the composition of marine Picoplankton communities. To achieve this goal, a multidisciplinary approach will be used, combining field observations made during 17 oceanographic campaigns in the Atlantic, Pacific and Indian tropical and subtropical oceans, the Northwest Mediterranean Sea, the Galician coastal upwelling ecosystem and the Antarctic Peninsula with laboratory experiments and ecological modeling of competitive interactions.Las regiones oligotróficas se caracterizan por una escasez de nutrientes en aguas superficiales, siendo el nitrógeno el principal nutriente limitante en la mayor parte de las regiones tropicales y subtropicales del océano abierto, así como en mares templados y polares durante períodos de estratificación estacional. Dado que una parte de la producción biológica en la capa fótica se exporta cara el océano profundo (exportación), el mantenimiento de la producción biológica dependerá de la entrada de nutrientes al sistema. Los mecanismos que contribuyen a la nueva producción incluyen la fijación biológica del nitrógeno, la deposición atmosférica y el transporte vertical y horizontal difusivo y advectivo de formas orgánicas e inorgánicas de nitrógeno. El cálculo del transporte difusivo vertical requiere de la estimación de la difusividad (Kz). Las dificultades metodológicas en la obtención de estimas de Kz motivaron la utilización de valores constantes de Kz, y parametrizaciones empíricas de difusividad vertical. Sin embargo, la comercialización de los perfiladores de turbulencia de microestructura ha facilitado la obtención de observaciones de turbulencia de microstructura, que revelaron una importante variabilidad de Kz en la capa superior. Alternativamente se ha utilizado la concentración de nutrientes inorgánicos disueltos en la capa fótica como un estimador de la disponibilidad de nutrientes para las comunidades planctónicas. Sin embargo, en condiciones de estado estacionario, como los giros subtropicales, donde el suministro de nutrientes por difusión hacia la zona eufótica es lento puede no existir relación entre la concentración de nutrientes en la capa fótica y su suministro. El picoplancton hace referencia a la fracción del plancton menor de 2 µm y está constituido por Synechococcus, picoeukaryotes, Prochlorococcus y bacterias heterótrofas. Estas últimas se pueden dividir entre bacterias con alto (HNA) o bajo (LNA) contenido en acidos nucleicos. Generalmente el picoplancton fotosintético domina la biomasa y la producción primaria en regiones oligotróficas tropicales y subtropicales, mientras que su contribución es menor en regiones costeras ricas en nutrientes. En los ecosistemas marinos, una fuente importante de heterogeneidad ambiental radica en la fluctuación temporal del suministros de nutrientes, que controla la diversidad de la comunidad de fitoplancton. En condiciones de estado estacionario, el nivel mínimo de recursos que puede sostener una población determina la competencia. Estudios experimentales y modelos numéricos de competición apoyan esta base teórica para el fitoplancton de gran tamaño. Mientras que numerosos estudios han investigado el efecto de la dinámica del suministro de nutrientes sobre la competencia interespecífica de especies de fitoplancton de gran tamaño, su efecto sobre los grupos que componen el picofitoplancton ha recibido mucha menos atención. La hipótesis principal de esta tesis es que la dinámica del suministro de nutrientes controla la composición de las comunidades de picoplancton marino. Para lograr este objetivo, se utilizará un enfoque multidisciplinar, combinando observaciones de campo realizadas durante 17 campañas oceanográficos realizadas en los océanos Atlántico, Pacífico e Índico tropicales y subtropicales, el Mar Mediterráneo Noroccidental, el ecosistema de afloramiento costero gallego y la Peninsula Antártica con experimentos de laboratorio y modelado ecológico de interacciones competitivas.As rexións oligotróficas caracterízanse por unha escaseza de nutrientes en augas superficiais, sendo o nitróxeno o principal nutriente limitante na maior parte das rexións tropicais e subtropicales do océano aberto, así como en mares tépedos e polares durante períodos de estratificación estacional. Dado que unha parte da produción biolóxica na capa fótica expórtase cara o océano profundo (exportación), o mantemento da produción biolóxica dependerá da entrada de nutrientes ao sistema. Os mecanismos que contribúen á nova produción inclúen a fixación biolóxica do nitróxeno, a deposición atmosférica e o transporte vertical e horizontal difusivo e advectivo de formas orgánicas e inorgánicas de nitróxeno. O cálculo do transporte difusivo vertical require da estimación da difusividad ( Kz). As dificultades metodolóxicas na obtención de estimas de Kz motivaron a utilización de valores constantes de Kz, e parametrizacións empíricas de difusividad vertical. Con todo, a comercialización dos perfiladores de turbulencia de microestructura facilitou a obtención de observacións de turbulencia de microstructura, que revelaron unha importante variabilidade de Kz na capa superior. Alternativamente utilizouse a concentración de nutrientes inorgánicos disoltos na capa fótica como un estimador da dispoñibilidade de nutrientes para as comunidades planctónicas. Con todo, en condicións de estado estacionario, como os xiros subtropicales, onde a subministración de nutrientes por difusión cara á zona eufótica é lento pode non existir relación entre a concentración de nutrientes na capa fótica e a súa subministración. O picoplancton fai referencia á fracción do plancto menor de 2 µ m e está constituído por Synechococcus, picoeukaryotes, Prochlorococcus e bacterias heterótrofas. Estas últimas pódense dividir entre bacterias con alto ( HNA) ou baixo ( LNA) contido en acidos nucleicos. Xeralmente o picoplancton fotosintético domina a biomasa e a produción primaria en rexións oligotróficas tropicais e subtropicales, mentres que a súa contribución é menor en rexións costeiras ricas en nutrientes. Nos ecosistemas mariños, unha fonte importante de heteroxeneidade ambiental radica na fluctuación temporal do subministracións de nutrientes, que controla a diversidade da comunidade de fitoplancto. En condicións de estado estacionario, o nivel mínimo de recursos que pode soster unha poboación determina a competencia. Estudos experimentais e modelos numéricos de competición apoian esta base teórica para o fitoplancto de gran tamaño. Mentres que numerosos estudos investigaron o efecto da dinámica da subministración de nutrientes sobre a competencia interespecífica de especies de fitoplancto de gran tamaño, o seu efecto sobre os grupos que compoñen o picofitoplancton recibiu moita menos atención. A hipótese principal desta tese é que a dinámica da subministración de nutrientes controla a composición das comunidades de picoplancton mariño. Para lograr este obxectivo, utilizarase un enfoque multidisciplinar, combinando observacións de campo realizadas durante 17 campañas oceanográficos realizadas nos océanos Atlántico, Pacífico e Índico tropicais e subtropicales, o Mar Mediterráneo Noroccidental, o ecosistema de afloramiento costeiro galego e a Península Antártica con experimentos de laboratorio e modelado ecolóxico de interaccións competitivas.Ministerio de Economía y Competitividad (Gobierno de España) |Ref. CTM2012-30680Ministerio de Economía y Competitividad (Gobierno de España) |Ref. EEBB-I-15-09468Ministerio de Economía y Competitividad (Gobierno de España) |Ref. EEBB-I-16-1148
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Factors controlling the community structure of Picoplankton in contrasting marine environments
Edith Cowan University Research Online Perth Western Australia, 2018Co-Authors: Otero-ferrer, Jose Luis, Cermeno Pedro, Bode Antonio, Fernandez-castro Bieito, Gasol, Josep M., Moran, Xose Anxelu G., Maranon Emilio, Moreira-coello Victor, Varela, Marta M., Villamana MarinaAbstract:The effect of inorganic nutrients on planktonic assemblages has traditionally relied on concentrations rather than estimates of nutrient supply. We combined a novel dataset of hydrographic properties, turbulent mixing, nutrient concentration, and Picoplankton community composition with the aims of (i) quantifying the role of temperature, light, and nitrate fluxes as factors controlling the distribution of autotrophic and heterotrophic Picoplankton subgroups, as determined by flow cytometry, and (ii) describing the ecological niches of the various components of the Picoplankton community. Data were collected at 97 stations in the Atlantic Ocean, including tropical and subtropical open-ocean waters, the northwestern Mediterranean Sea, and the Galician coastal upwelling system of the northwest Iberian Peninsula. A generalized additive model (GAM) approach was used to predict depth-integrated biomass of each Picoplankton subgroup based on three niche predictors: sea surface temperature, averaged daily surface irradiance, and the transport of nitrate into the euphotic zone, through both diffusion and advection. In addition, niche overlap among different Picoplankton subgroups was computed using nonparametric kernel density functions. Temperature and nitrate supply were more relevant than light in predicting the biomass of most Picoplankton subgroups, except for Prochlorococcus and low-nucleic-acid (LNA) prokaryotes, for which irradiance also played a significant role. Nitrate supply was the only factor that allowed the distinction among the ecological niches of all autotrophic and heterotrophic Picoplankton subgroups. Prochlorococcus and LNA prokaryotes were more abundant in warmer waters ( \u3e 20°C) where the nitrate fluxes were low, whereas Synechococcus and high-nucleic-acid (HNA) prokaryotes prevailed mainly in cooler environments characterized by intermediate or high levels of nitrate supply. Finally, the niche of picoeukaryotes was defined by low temperatures and high nitrate supply. These results support the key role of nitrate supply, as it not only promotes the growth of large phytoplankton, but it also controls the structure of marine Picoplankton communities
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Factors controlling the community structure of Picoplankton in contrasting marine environments
'Copernicus GmbH', 2018Co-Authors: Otero-ferrer, Jose Luis, Fernández-castro B., Cermeno Pedro, Bode Antonio, Gasol, Josep M., Moran, Xose Anxelu G., Maranon Emilio, Moreira-coello Victor, Varela, Marta M., Villamana MarinaAbstract:22 pages, 4 tables, 5 figuresThe effect of inorganic nutrients on planktonic assemblages has traditionally relied on concentrations rather than estimates of nutrient supply. We combined a novel dataset of hydrographic properties, turbulent mixing, nutrient concentration, and Picoplankton community composition with the aims of (i) quantifying the role of temperature, light, and nitrate fluxes as factors controlling the distribution of autotrophic and heterotrophic Picoplankton subgroups, as determined by flow cytometry, and (ii) describing the ecological niches of the various components of the Picoplankton community. Data were collected at 97 stations in the Atlantic Ocean, including tropical and subtropical open-ocean waters, the northwestern Mediterranean Sea, and the Galician coastal upwelling system of the northwest Iberian Peninsula. A generalized additive model (GAM) approach was used to predict depth-integrated biomass of each Picoplankton subgroup based on three niche predictors: sea surface temperature, averaged daily surface irradiance, and the transport of nitrate into the euphotic zone, through both diffusion and advection. In addition, niche overlap among different Picoplankton subgroups was computed using nonparametric kernel density functions. Temperature and nitrate supply were more relevant than light in predicting the biomass of most Picoplankton subgroups, except for Prochlorococcus and lownucleic- acid (LNA) prokaryotes, for which irradiance also played a significant role. Nitrate supply was the only factor that allowed the distinction among the ecological niches of all autotrophic and heterotrophic Picoplankton subgroups. Prochlorococcus and LNA prokaryotes were more abundant in warmer waters ( > 20 C) where the nitrate fluxes were low, whereas Synechococcus and high-nucleic-acid (HNA) prokaryotes prevailed mainly in cooler environments characterized by intermediate or high levels of nitrate supply. Finally, the niche of picoeukaryotes was defined by low temperatures and high nitrate supply. These results support the key role of nitrate supply, as it not only promotes the growth of large phytoplankton, but it also controls the structure of marine Picoplankton communitiesThis research was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) through projects CTM2012-30680 to Beatriz Mouriño, CTM2008-0626I-C03-01 to Mikel Latasa, REN2003-09532-C03-01 to Ramiro Varela Benvenuto, CTM2004-05174-C02 to Emilio Marañón, and CTM2011- 25035 to Pedro Cermeño; by the Galician government through grants 09MMA027604PR to Manuel Ruiz Villareal and EM2013/021 to Beatriz Mouriño; by the Instituto Español de Oceanografia (IEO) through the time series project RADIALES coordinated by Antonio Bode and by the 7th Framework Programme of the European Commission through grant FP7 SPACE.2010.1.1- 01 261860 to Manuel Ruiz Villareal. Jose Luis Otero Ferrer acknowledges the receipt of a FPI contract from MINECO (CTM2012-30680) and Bieito Fernádez Castro a Juan de La Cierva Formación fellowship (FJCI-641 2015-25712, Ministerio de Economía y Competitividad, Spanish government)Peer reviewe
Ramiro Logares - One of the best experts on this subject based on the ideXlab platform.
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Eukaryotic versus prokaryotic marine Picoplankton ecology
Environmental Microbiology, 2012Co-Authors: Ramon Massana, Ramiro LogaresAbstract:Summary Marine microorganisms contribute markedly to global biomass and ecosystem function. They include a diverse collection of organisms differing in cell size and in evolutionary history. In particular, microbes within the Picoplankton are similar in size but belong to two drastically different cellular plans, the prokaryotes and the eukaryotes. Compared with larger organisms, prokaryotes and picoeukaryotes share ecological features, such as high specific activity, large and constant abundances, and high dispersal potential. Still, there are some aspects where their different cell organization influences their ecological performance. First, prokaryotes have a huge metabolic versatility and are involved in all biogeochemical cycles, whereas picoeukaryotes are metabolically less flexible but can exploit diverse predatory life strategies due to their phagocytic capacity. Second, sexual reproduction is absent in prokaryotes but may be present in picoeukaryotes, thus determining different evolutionary diversification dynamics and making species limits clearer in picoeukaryotes. Finally, it is plausible that picoeukaryotes are less flexible to enter a reversible state of low metabolic activity, thus picoeukaryote assemblages may have fewer rare species and may be less resilient to environmental change. In summary, lumping together pico-sized microbes may be convenient for some ecological studies, but it is also important to keep in mind their differences.
Erik Von Alert - One of the best experts on this subject based on the ideXlab platform.
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Trophic upgrading of autotrophic Picoplankton by the heterotrophic nanoflagellate Paraphysomonas sp
Limnology and Oceanography, 2006Co-Authors: Alexandre Bec, Dominik Martin-creuzburg, Erik Von AlertAbstract:We investigated whether trophic repackaging of autotrophic Picoplankton by phagotrophic protists is associated with an improvement in food quality for the metazooplankton Daphnia magna (i.e., whether trophic upgrading occurs in this system). The nutritional value of the autotrophic species Microcystis aeruginosa PCC7806, Synechococcus sp. strain BO8809, Synechococcus elongatus SAG 89.79, and Choricystis minor KR1988/ 8, and of the heterotrophic nanoflagellate Paraphysomonas sp. grown on these different Picoplanktonic species was evaluated in standardized growth experiments with D. magna. In order to investigate the functional role of the flagellate in the simplified autotrophic Picoplankton-Daphnia food chain, Paraphysomonas sp. was grown on the different Picoplanktonic organisms and subsequently separated from the food items before being fed to D. magna. The presence of Paraphysomonas sp. as an intermediary trophic step enhanced somatic growth and reproduction of D. magna. Supplementation of Synechococcus sp. with lipids from Paraphysomonas sp. (grown on Synechococcus sp.) revealed that trophic upgrading of autotrophic Picoplankton is due to the additional lipids present in the flagellate. Paraphysomonas sp. synthesized polyunsaturated fatty acids and sterols de novo, which most likely explains the trophic upgrading. Paraphysomonas sp. also improved the food quality of M. aeruginosa PCC7806, which is toxic for D. magna. The heterotrophic flagellate Paraphysomonas sp. is capable of trophically upgrading a poor quality food source not only by producing essential lipids, but also by detoxifying the cyanobacterial food organism.
Edward F Delong - One of the best experts on this subject based on the ideXlab platform.
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pattern and synchrony of gene expression among sympatric marine microbial populations
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Elizabeth A Ottesen, Curtis R Young, John M Eppley, John P Ryan, Francisco P Chavez, Christopher A Scholin, Edward F DelongAbstract:Planktonic marine microbes live in dynamic habitats that demand rapid sensing and response to periodic as well as stochastic environmental change. The kinetics, regularity, and specificity of microbial responses in situ, however, are not well-described. We report here simultaneous multitaxon genome-wide transcriptome profiling in a naturally occurring Picoplankton community. An in situ robotic sampler using a Lagrangian sampling strategy enabled continuous tracking and repeated sampling of coherent microbial populations over 2 d. Subsequent RNA sequencing analyses yielded genome-wide transcriptome profiles of eukaryotic (Ostreococcus) and bacterial (Synechococcus) photosynthetic Picoplankton as well as proteorhodopsin-containing heterotrophs, including Pelagibacter, SAR86-cluster Gammaproteobacteria, and marine Euryarchaea. The photosynthetic Picoplankton exhibited strong diel rhythms over thousands of gene transcripts that were remarkably consistent with diel cycling observed in laboratory pure cultures. In contrast, the heterotrophs did not cycle diurnally. Instead, heterotrophic Picoplankton populations exhibited cross-species synchronous, tightly regulated, temporally variable patterns of gene expression for many genes, particularly those genes associated with growth and nutrient acquisition. This multitaxon, population-wide gene regulation seemed to reflect sporadic, short-term, reversible responses to high-frequency environmental variability. Although the timing of the environmental responses among different heterotrophic species seemed synchronous, the specific metabolic genes that were expressed varied from taxon to taxon. In aggregate, these results provide insights into the kinetics, diversity, and functional patterns of microbial community response to environmental change. Our results also suggest a means by which complex multispecies metabolic processes could be coordinated, facilitating the regulation of matter and energy processing in a dynamically changing environment.
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Abundance and distribution of plankton Archaea and Bacteria in the waters west of the Antarctic Peninsula. Limnol Oceanogr 48
2003Co-Authors: Matthew J. Church, Edward F Delong, Hw Ducklow, Cm Preston, Markus B. Karner, David M. KarlAbstract:Polyribonucleotide probes targeting planktonic archaeal (Group I and II) and bacterial rRNA revealed that Archaea comprised a significant fraction of total prokaryote cell abundance in the marine waters west of the Antarctic Peninsula. Determinations of Archaea and Bacteria cell abundances were made during two research cruises to the Palmer Long-Term Ecological Research region during the austral winter and summer of 1999. During the austral summer, surface water abundances of Group I (GI) Archaea were generally low, averaging 4.7 � 103 cells ml�1 and accounting for 1 % of the total Picoplankton assemblage. The abundance of GI Archaea increased significantly with depth, averaging 2.1 � 104 cells ml�1 and comprising 9–39 % of the total Picoplankton abundance in the meso-(150–1,000 m) and bathypelagic (1,000–3,500 m) circumpolar deep water (CDW). Relative to summertime distributions, GI cells were more evenly distributed throughout the water column during the winter, averaging 10 % of the Picoplankton in the surface waters and 13 % in the CDW. Surface water GI abundance increased 44 % between the summer and winter, coincident with a fivefold decrease in GI abundance in the deeper waters. The abundance of Group II (GII) Archaea was persistently �2 % of the total Picoplankton throughout the water column in both summer and winter. Bacterial abundance was greatest in the upper water column (0–100 m) during the summer, averaging 3.9 � 105 cells ml�1 and comprised 89 % of the total Picoplankton assemblage. Generally, GI Archae
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high abundance of archaea in antarctic marine Picoplankton
Nature, 1994Co-Authors: Edward F Delong, Barbara B Prezelin, Raffael V M JovineAbstract:ARCHAEA (archaebacteria) constitute one of the three major evolu-tionary lineages of life on Earth1–3. Previously these prokaryotes were thought to predominate in only a few unusual and disparate niches, characterized by hypersaline, extremely hot, or strictly anoxic conditions4–7. Recently, novel (uncultivated) phylotypes of Archaea have been detected in coastal8 and subsurface9,10 marine waters, but their abundance, distribution, physiology and ecology remain largely undescribed. Here we report exceptionally high archaeal abundance in frigid marine surface waters of Antarctica. Pelagic Archaea constituted up to 34% of the prokaryotic biomass in coastal Antarctic surface waters, and they were also abundant in a variety of other cold, pelagic marine environments. Because they can make up a significant fraction of Picoplankton biomass in the vast habitats encompassed by cold and deep marine waters, these pelagic Archaea represent an unexpectedly abundant component of the Earth's biota.
Ramon Massana - One of the best experts on this subject based on the ideXlab platform.
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Eukaryotic versus prokaryotic marine Picoplankton ecology
Environmental Microbiology, 2012Co-Authors: Ramon Massana, Ramiro LogaresAbstract:Summary Marine microorganisms contribute markedly to global biomass and ecosystem function. They include a diverse collection of organisms differing in cell size and in evolutionary history. In particular, microbes within the Picoplankton are similar in size but belong to two drastically different cellular plans, the prokaryotes and the eukaryotes. Compared with larger organisms, prokaryotes and picoeukaryotes share ecological features, such as high specific activity, large and constant abundances, and high dispersal potential. Still, there are some aspects where their different cell organization influences their ecological performance. First, prokaryotes have a huge metabolic versatility and are involved in all biogeochemical cycles, whereas picoeukaryotes are metabolically less flexible but can exploit diverse predatory life strategies due to their phagocytic capacity. Second, sexual reproduction is absent in prokaryotes but may be present in picoeukaryotes, thus determining different evolutionary diversification dynamics and making species limits clearer in picoeukaryotes. Finally, it is plausible that picoeukaryotes are less flexible to enter a reversible state of low metabolic activity, thus picoeukaryote assemblages may have fewer rare species and may be less resilient to environmental change. In summary, lumping together pico-sized microbes may be convenient for some ecological studies, but it is also important to keep in mind their differences.
