Iglesias-Rodriguez
M. Debora
Iglesias-Rodriguez
M. Debora
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ArticleThe effect of nitrate and phosphate availability on Emiliania huxleyi (NZEH) physiology under different CO2 scenarios(Frontiers Media, 2013-06-18) Rouco, Monica ; Branson, Oscar ; Lebrato, Mario ; Iglesias-Rodriguez, M. DeboraGrowth and calcification of the marine coccolithophorid Emiliania huxleyi is affected by ocean acidification and macronutrients limitation and its response varies between strains. Here we investigated the physiological performance of a highly calcified E. huxleyi strain, NZEH, in a multiparametric experiment. Cells were exposed to different CO2 levels (ranging from 250 to 1314 μatm) under three nutrient conditions [nutrient replete (R), nitrate limited (-N), and phosphate limited (-P)]. We focused on calcite and organic carbon quotas and on nitrate and phosphate utilization by analyzing the activity of nitrate reductase (NRase) and alkaline phosphatase (APase), respectively. Particulate inorganic (PIC) and organic (POC) carbon quotas increased with increasing CO2 under R conditions but a different pattern was observed under nutrient limitation. The PIC:POC ratio decreased with increasing CO2 in nutrient limited cultures. Coccolith length increased with CO2 under all nutrient conditions but the coccosphere volume varied depending on the nutrient treatment. Maximum APase activity was found at 561 μatm of CO2 (pH 7.92) in -P cultures and in R conditions, NRase activity increased linearly with CO2. These results suggest that E. huxleyi's competitive ability for nutrient uptake might be altered in future high-CO2 oceans. The combined dataset will be useful in model parameterizations of the carbon cycle and ocean acidification.
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ArticleUnderstanding the role of the biological pump in the global carbon cycle : an imperative for ocean science(The Oceanography Society, 2014-09) Honjo, Susumu ; Eglinton, Timothy I. ; Taylor, Craig D. ; Ulmer, Kevin M. ; Sievert, Stefan M. ; Bracher, Astrid ; German, Christopher R. ; Edgcomb, Virginia P. ; Francois, Roger ; Iglesias-Rodriguez, M. Debora ; Van Mooy, Benjamin A. S. ; Repeta, Daniel J.Anthropogenically driven climate change will rapidly become Earth's dominant transformative influence in the coming decades. The oceanic biological pump—the complex suite of processes that results in the transfer of particulate and dissolved organic carbon from the surface to the deep ocean—constitutes the main mechanism for removing CO2 from the atmosphere and sequestering carbon at depth on submillennium time scales. Variations in the efficacy of the biological pump and the strength of the deep ocean carbon sink, which is larger than all other bioactive carbon reservoirs, regulate Earth's climate and have been implicated in past glacial-interglacial cycles. The numerous biological, chemical, and physical processes involved in the biological pump are inextricably linked and heterogeneous over a wide range of spatial and temporal scales, and they influence virtually the entire ocean ecosystem. Thus, the functioning of the oceanic biological pump is not only relevant to the modulation of Earth's climate but also constitutes the basis for marine biodiversity and key food resources that support the human population. Our understanding of the biological pump is far from complete. Moreover, how the biological pump and the deep ocean carbon sink will respond to the rapid and ongoing anthropogenic changes to our planet—including warming, acidification, and deoxygenation of ocean waters—remains highly uncertain. To understand and quantify present-day and future changes in biological pump processes requires sustained global observations coupled with extensive modeling studies supported by international scientific coordination and funding.
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ArticleGlobal variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean(National Academy of Sciences, 2020-07-17) Lebrato, Mario ; Garbe-Schonberg, Dieter ; Müller, Marius N. ; Blanco-Ameijeiras, Sonia ; Feely, Richard A. ; Lorenzoni, Laura ; Molinero, Juan-Carlos ; Bremer, Karen ; Jones, Daniel O. B. ; Iglesias-Rodriguez, M. Debora ; Greeley, Dana ; Lamare, Miles D. ; Paulmier, Aurelien ; Graco, Michelle ; Cartes, Joan ; Barcelos e Ramos, Joana ; de Lara, Ana ; Sanchez-Leal, Ricardo ; Jimenez, Paz ; Paparazzo, Flavio E. ; Hartman, Susan ; Westernströer, Ulrike ; Küter, Marie ; Benavides, Roberto ; da Silva, Armindo F. ; Bell, Steven ; Payne, Chris ; Olafsdottir, Solveig R. ; Robinson, Kelly ; Jantunen, Liisa M. ; Korablev, Alexander ; Webster, Richard J. ; Jones, Elizabeth M. ; Gilg, Olivier ; Bailly du Bois, Pascal ; Beldowski, Jacek ; Ashjian, Carin J. ; Yahia, Nejib D. ; Twining, Benjamin S. ; Chen, Xue-Gang ; Tseng, Li-Chun ; Hwang, Jiang-Shiou ; Dahms, Hans-Uwe ; Oschlies, AndreasSeawater Mg:Ca and Sr:Ca ratios are biogeochemical parameters reflecting the Earth–ocean–atmosphere dynamic exchange of elements. The ratios’ dependence on the environment and organisms' biology facilitates their application in marine sciences. Here, we present a measured single-laboratory dataset, combined with previous data, to test the assumption of limited seawater Mg:Ca and Sr:Ca variability across marine environments globally. High variability was found in open-ocean upwelling and polar regions, shelves/neritic and river-influenced areas, where seawater Mg:Ca and Sr:Ca ratios range from ∼4.40 to 6.40 mmol:mol and ∼6.95 to 9.80 mmol:mol, respectively. Open-ocean seawater Mg:Ca is semiconservative (∼4.90 to 5.30 mol:mol), while Sr:Ca is more variable and nonconservative (∼7.70 to 8.80 mmol:mol); both ratios are nonconservative in coastal seas. Further, the Ca, Mg, and Sr elemental fluxes are connected to large total alkalinity deviations from International Association for the Physical Sciences of the Oceans (IAPSO) standard values. Because there is significant modern seawater Mg:Ca and Sr:Ca ratios variability across marine environments we cannot absolutely assume that fossil archives using taxa-specific proxies reflect true global seawater chemistry but rather taxa- and process-specific ecosystem variations, reflecting regional conditions. This variability could reconcile secular seawater Mg:Ca and Sr:Ca ratio reconstructions using different taxa and techniques by assuming an error of 1 to 1.50 mol:mol, and 1 to 1.90 mmol:mol, respectively. The modern ratios’ variability is similar to the reconstructed rise over 20 Ma (Neogene Period), nurturing the question of seminonconservative behavior of Ca, Mg, and Sr over modern Earth geological history with an overlooked environmental effect.