Uptake of half the fossil fuel CO 2 into ocean causes gradual seawater acidification. This has been shown to slow down calcification major calcifying groups, such as corals, foraminifera, and coccolithophores. Here we show that two most productive marine species, coccolithophores Coccolithus pelagicus Calcidiscus leptoporus , do not follow ‐related response previously found. In batch culture experiments, particulate inorganic carbon (PIC) C. changes with increasing concentration in a...

Abstract. A methane surplus relative to the atmospheric equilibrium is a frequently observed feature of ocean surface water. Despite common fact that biological processes are responsible for its origin, formation in aerobic water still poorly understood. We report on production central Arctic Ocean, which was exclusively detected Pacific derived but not nearby Atlantic The two masses distinguished by their different nitrate phosphate ratios. show occurs if depleted available as P source....

The effects of pH-induced changes in seawater carbonate chemistry on inorganic carbon (C(i)) acquisition and domoic acid (DA) production were studied two potentially toxic diatom species, Pseudo-nitzschia multiseries Nitzschia navis-varingica, the non-toxic Stellarima stellaris. In vivo activities carbonic anhydrase (CA), photosynthetic O(2) evolution CO(2) HCO(3)(-) uptake rates measured by membrane inlet MS cells acclimated to low (7.9) high pH (8.4 or 8.9). Species-specific differences...

Abstract. During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by is exuded in the form organic (DOC), which can be transformed into extracellular particulate (POC). A major POC associated with transparent exopolymer particles (TEP; content = TEPC) that from polysaccharides (PCHO). The exudation PCHO linked to an excessive uptake DIC not directly quantifiable utilisation nitrogen (DIN), called overconsumption. Given these conditions, concept assuming...

Research Article| August 01, 2006 Cellular calcium pathways and isotope fractionation in Emiliania huxleyi Nikolaus Gussone; Gussone 1Research Centre Ocean Margins, University of Bremen, P.O. Box 330440, D-28334 Germany Search for other works by this author on: GSW Google Scholar Gerald Langer; Langer 2Alfred Wegener Institute Polar Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Silke Thoms; Thoms Gernot Nehrke; Nehrke Anton Eisenhauer; Eisenhauer 3Leibniz Sciences at the Kiel,...

In recent studies the Sr/Ca ratio of coccolithophore calcite was used as a proxy for past growth and calcification rates. Since Sr Ca concentrations in seawater have not remained constant through time, interpretation data from coccolith-dominated sedimentary record requires knowledge about incorporation into coccolith during coccolithogenesis. Here we show that Emiliania huxleyi coccoliths is linearly related to Sr/Ca, meaning exchange coefficient does change with changing Sr/Ca. The this...

To better understand the impact of ocean acidification ( OA ) and changes in light availability on Southern Ocean phytoplankton physiology, we investigated effects pCO 2 (380 800 µatm) combination with low high irradiance (20 or 50 200 µmol photons m −2 s −1 growth, particulate organic carbon POC fixation photophysiology three ecologically relevant species Chaetoceros debilis , Fragilariopsis kerguelensis Phaeocystis antarctica . Irrespective scenario, neither growth nor per cell was...

Recently, calcium isotope fractionation in the coccolithophore Emiliania huxleyi was shown to exhibit a significant temperature dependency. An important subsequent question this context is whether observed patterns are caused by itself or related growth rate changes. In order separate and calcification effects from direct effects, batch culture experiments with E. were conducted under varying light intensities. Despite large changes cellular rates, remained constant. Independence of on also...

Abstract. The oxygen isotopic composition (δ18O) of calcium carbonate planktonic calcifying organisms is a key tool for reconstructing both past seawater temperature and salinity. calibration paloeceanographic proxies relies in general on empirical relationships derived from field experiments extant species. Laboratory have more often than not revealed that variables other the target parameter influence proxy signal, which makes challenging task. Understanding these secondary or "vital"...

A system of differential equations was presented which describes the rate linear and cyclic electron flow through photosystems II I. The photochemistry in terms electrons generated that are available for cellular metabolism, results a realistic description photosynthesis as function irradiance without implicit assumptions relationship. allows concise detailed simulation fluorescence kinetics. derivation general degree reduction (γ x ) its application to translate rates (or measured yields)...

The present study examines how different pCO2 acclimations affect the CO2- and light-dependence of photophysiological processes O2 fluxes in four Southern Ocean (SO) key phytoplankton species. We grew Chaetoceros debilis (Cleve), Pseudo-nitzschia subcurvata (Hasle), Fragilariopsis kerguelensis (O'Meara) Phaeocystis antarctica (Karsten) under low (160 μatm) high (1000 pCO2. fluorescence parameters photosystem II (PSII) were determined by means a induction relaxation system (FIRe). In all...

Although iron (Fe) availability primarily sets the rate of phytoplankton growth and primary export production in Southern Ocean, other environmental factors, most significantly light, also affect productivity. As light strongly influences species distribution low Fe-waters, we investigated combined effects increasing (20, 200 500 μmol photons m−2 s−1) conjunction with different Fe (0.4 2 nM Fe) on physiology two ecologically relevant Chaetoceros debilis (Bacillariophyceae) Phaeocystis...

Coccolithophores play a crucial role in the marine carbon cycle and thus it is interesting to know how they will respond climate change. After several decades of research interplay between intracellular processes carbonate system still not well understood. On basis experimental findings given literature, numerical cell model developed that describes inorganic fluxes seawater sites calcite precipitation photosynthetic fixation. The implemented consists four compartments, for each which...

Ocean acidification (OA) and high light was found to negatively affect the Antarctic key species Phaeocystis antarctica, Fragilariopsis kerguelensis Chaetoceros debilis. To unravel underlying physiological response at transcriptomic level, these were grown under ambient elevated pCO2 combined with low or light. RNA sequencing revealed that haptophyte much more tolerant towards OA than two diatoms as only showed distinct OA-dependent gene regulation patterns. Under pCO2, resulted in decreased...

Abstract The toxin‐producing dinoflagellate Alexandrium pseudogonyaulax has become increasingly abundant in northern European waters, replacing other species. A. produces goniodomins and lytic substances, which can be cytotoxic toward organisms, including fish, but we still know little about the environmental conditions influencing its growth toxicity. Here, investigated impacts of different nitrogen sources light intensities, common bottom‐up drivers bloom formation, on toxin content three...

Abstract. Mg / Ca ratios in foraminiferal tests are routinely used as paleotemperature proxies, but on long timescales, they also hold the potential to reconstruct past seawater Ca. The impact of both temperature and incorporation Foraminifera has been quantified by a number studies. underlying mechanism responsible for calcite its sensitivity environmental conditions, however, not fully identified. A recently published biomineralization model (Nehrke et al., 2013) proposes combination...

To predict effects of climate change on phytoplankton, it is crucial to understand how their mechanisms for carbon acquisition respond environmental conditions. Aiming shed light the responses extra- and intracellular inorganic C (Ci) fluxes, cyanobacterium Trichodesmium erythraeum IMS101 was grown with different nitrogen sources (N2 vs NO3–) pCO2 levels (380 1400 µatm). Cellular Ci fluxes were assessed by combining membrane inlet mass spectrometry (MIMS), 13C fractionation measurements,...

Summary To understand the role of micrometer‐scale oxygen (O 2 ) gradients in facilitating dinitrogen (N fixation, we characterized O dynamics microenvironment around free‐floating trichomes and colonies Trichodesmium erythraeum IMS 101. Diurnal spatial variability concentrations bulk medium, within colonies, along single cells were determined using optodes, microsensors model calculations. Carbon (C) N fixation as well evolution uptake under different analyzed by stable isotope incubations...