cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.1594/pangaea.830881
title: Response of Nodularia spumigena to pCO2 - Part 3: Turnover of phosphorus compounds

description: Diazotrophic cyanobacteria often form extensive summer blooms in the Baltic Sea driving their environment into phosphate limitation. One of the main species is the heterocystous cyanobacterium Nodularia spumigena. N. spumigena exhibits accelerated uptake of phosphate through the release of the exoenzyme alkaline phosphatase that also serves as an indicator of the hydrolysis of dissolved organic phosphorus (DOP). The present study investigated the utilization of DOP and its compounds (e.g. ATP) by N. spumigena during growth under varying CO2 concentrations, in order to estimate potential consequences of ocean acidification on the cell's supply with phosphorus. Cell growth, phosphorus pool fractions, and four DOP-compounds (ATP, DNA, RNA, and phospholipids) were determined in three set-ups with different CO2 concentrations (341, 399, and 508 µatm) during a 15-day batch experiment. The results showed rapid depletion of dissolved inorganic phosphorus (DIP) in all pCO2 treatments while DOP utilization increased with elevated pCO2, in parallel with the growth stimulation of N. spumigena. During the growth phase, DOP uptake was enhanced by a factor of 1.32 at 399 µatm and of 2.25 at 508 µatm compared to the lowest pCO2 concentration. Among the measured DOP compounds, none was found to accumulate preferentially during the incubation or in response to a specific pCO2 treatment. However, at the beginning 61.9 ± 4.3% of the DOP were not characterized but comprised the most highly utilized fraction. This is demonstrated by the decrement of this fraction to 27.4 ± 9.9% of total DOP during the growth phase, especially in response to the medium and high pCO2 treatment. Our results indicate a stimulated growth of diazotrophic cyanobacteria at increasing CO2 concentrations that is accompanied by increasing utilization of DOP as an alternative P source.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2014-03-21.
description: Supplement to: Unger, Juliane; Endres, Sonja; Wannicke, Nicola; Engel, Anja; Voss, Maren; Nausch, Günther; Nausch, Monika (2013): Response of Nodularia spumigena to pCO2–Part 3: Turnover of phosphorus compounds. Biogeosciences, 10(3), 1483-1499
DOI: 10.1594/pangaea.777430
title: Seawater carbonate chemistry and combined physiological effects of CO2 and light on the N2-fixing cyanobacterium Trichodesmium IMS101 during experiments, 2010

description: Recent studies on the diazotrophic cyanobacterium Trichodesmium erythraeum(IMS101) showed that increasing CO2 partial pressure (pCO2) enhances N2 fixation and growth. Significant uncertainties remain as to the degree of the sensitivity to pCO2, its modification by other environmental factors, and underlying processes causing these responses. To address these questions, we examined the responses ofTrichodesmium IMS101 grown under a matrix of low and high levels of pCO2 (150 and 900 µatm) and irradiance (50 and 200 µmol photons m-2 s-1). Growth rates as well as cellular carbon and nitrogen contents increased with increasing pCO2 and light levels in the cultures. The pCO2-dependent stimulation in organic carbon and nitrogen production was highest under low light. High pCO2 stimulated rates of N2fixation and prolonged the duration, while high light affected maximum rates only. Gross photosynthesis increased with light but did not change with pCO2. HCO3- was identified as the predominant carbon source taken up in all treatments. Inorganic carbon uptake increased with light, but only gross CO2 uptake was enhanced under high pCO2. A comparison between carbon fluxes in vivo and those derived from 13C fractionation indicates high internal carbon cycling, especially in the low-pCO2treatment under high light. Light-dependent oxygen uptake was only detected underlow pCO2 combined with high light or when low-light-acclimated cells were exposed to high light, indicating that the Mehler reaction functions also as a photoprotective mechanism in Trichodesmium. Our data confirm the pronounced pCO2 effect on N2fixation and growth in Trichodesmium and further show a strong modulation of these effects by light intensity. We attribute these responses to changes in the allocation of photosynthetic energy between carbon acquisition and the assimilation of carbon and nitrogen under elevated pCO2. These findings are supported by a complementarystudy looking at photosynthetic fluorescence parameters of photosystem II, photosynthetic unit stoichiometry (photosystem I:photosystem II), and pool sizes of key proteins in carbon and nitrogen acquisition.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI).
description: Supplement to: Kranz, Sven A; Levitan, Orly; Richter, Klaus-Uwe; Prasil, O; Beran-Frank, Ilana; Rost, Björn (2010): Combined effects of CO2 and light on the N2-fixing cyanobacterium Trichodesmium IMS101: Physiological responses. Plant Physiology, 154, 334-345
DOI: 10.1594/pangaea.835715
title: Impact of elevated pCO2 on paralytic shellfish poisoning toxin content and composition in Alexandrium tamarense

description: Ocean acidification is considered a major threat to marine ecosystems and may particularly affect primary producers. Here we investigated the impact of elevated pCO2 on paralytic shellfish poisoning toxin (PST) content and composition in two strains of Alexandrium tamarense, Alex5 and Alex2. Experiments were carried out as dilute batch to keep carbonate chemistry unaltered over time. We observed only minor changes with respect to growth and elemental composition in response to elevated pCO2. For both strains, the cellular PST content, and in particular the associated cellular toxicity, was lower in the high CO2 treatments. In addition, Alex5 showed a shift in its PST composition from a nonsulfated analogue towards less toxic sulfated analogues with increasing pCO2. Transcriptomic analyses suggest that the ability of A. tamarense to maintain cellular homeostasis is predominantly regulated on the post-translational level rather than on the transcriptomic level. Furthermore, genes associated to secondary metabolite and amino acid metabolism in Alex5 were down-regulated in the high CO2 treatment, which may explain the lower PST content. Elevated pCO2 also induced up-regulation of a putative sulfotransferase sxtN homologue and a substantial down-regulation of several sulfatases. Such changes in sulfur metabolism may explain the shift in PST composition towards more sulfated analogues. All in all, our results indicate that elevated pCO2 will have minor consequences for growth and elemental composition, but may potentially reduce the cellular toxicity of A. tamarense.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne et al, 2014) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation is 2014-09-11.
description: Supplement to: Van de Waal, Dedmer B; Eberlein, Tim; John, Uwe; Wohlrab, Sylke; Rost, Björn (2014): Impact of elevated pCO2 on paralytic shellfish poisoning toxin content and composition in Alexandrium tamarense. Toxicon, 78, 58-67
DOI: 10.1594/pangaea.951402
title: Seawater carbonate chemistry and growth, elemental composition,biomass production, respiration and carbon acquisition of diatoms Thalassiosira hyalina and Melosira arctica

description: Sea ice retreat, changing stratification, and ocean acidification are fundamentally changing the light availability and physico-chemical conditions for primary producers in the Arctic Ocean. However, detailed studies on ecophysiological strategies and performance of key species in the pelagic and ice-associated habitat remain scarce. Therefore, we investigated the acclimated responses of the diatoms Thalassiosira hyalina and Melosira arctica toward elevated irradiance and CO2 partial pressures (pCO2). Next to growth, elemental composition, and biomass production, we assessed detailed photophysiological responses through fluorometry and gas-flux measurements, including respiration and carbon acquisition. In the pelagic T. hyalina, growth rates remained high in all treatments and biomass production increased strongly with light. Even under low irradiances cells maintained a high-light acclimated state, allowing them to opportunistically utilize high irradiances by means of a highly plastic photosynthetic machinery and carbon uptake. The ice-associated M. arctica proved to be less plastic and more specialized on low-light. Its acclimation to high irradiances was characterized by minimizing photon harvest and photosynthetic efficiency, which led to lowered growth. Comparably low growth rates and strong silification advocate a strategy of persistence rather than of fast proliferation, which is also in line with the observed formation of resting stages under low-light conditions. In both species, responses to elevated pCO2 were comparably minor. Although both diatom species persisted under the applied conditions, their competitive abilities and strategies differ strongly. With the anticipated extension of Arctic pelagic habitats, flexible high-light specialists like T. hyalina seem to face a brighter future.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2021) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2022-11-30.
DOI: 10.1594/pangaea.778475
title: Seawater carbonate chemistry, nutrients, and Calcidiscus leptoporus (strain RCC1135) growth rate and calcification rate during experiments, 2012

description: The coccolithophore Calcidiscus leptoporus was grown in batch culture under nitrogen (N) as well as phosphorus (P) limitation. Growth rate, particulate inorganic carbon (PIC), particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate organic phosphorus (POP) production were determined and coccolith morphology was analysed. While PON production decreased by 70% under N-limitation and POP production decreased by 65% under P-limitation, growth rate decreased by 33% under N- as well as P-limitation. POC as well as PIC production (calcification rate) increased by 27% relative to the control under P-limitation, and did not change under N-limitation. Coccolith morphology did not change in response to either P or N limitation. While these findings, supported by a literature survey, suggest that coccolith morphogenesis is not hampered by either P or N limitation, calcification rate might be. The latter conclusion is in apparent contradiction to our data. We discuss the reasons for this inference.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI).
description: Supplement to: Langer, Gerald; Oetjen, Kerstin; Brenneis, Tina (2012): Calcification of Calcidiscus leptoporus under nitrogen and phosphorus limitation. Journal of Experimental Marine Biology and Ecology, 413, 131-137
DOI: 10.1594/pangaea.829376
title: Experiment: Influence of CO2 and nitrogen limitation on the coccolith volume of Emiliania huxleyi (Haptophyta)

description: Coccolithophores, a key phytoplankton group, are one of the most studied organisms regarding their physiological response to ocean acidification/carbonation. The biogenic production of calcareous coccoliths has made coccolithophores a promising group for paleoceanographic research aiming to reconstruct past environmental conditions. Recently, geochemical and morphological analyses of fossil coccoliths have gained increased interest in regard to changes in seawater carbonate chemistry. The cosmopolitan coccolithophore Emiliania huxleyi (Lohm.) Hay and Mohler was cultured over a range of pCO2 levels in controlled laboratory experiments under nutrient replete and nitrogen limited conditions. Measurements of photosynthesis and calcification revealed, as previously published, an increase in particulate organic carbon production and a moderate decrease in calcification from ambient to elevated pCO2. The enhancement in particulate organic carbon production was accompanied by an increase in cell diameter. Changes in coccolith volume were best correlated with the coccosphere/cell diameter and no significant correlation was found between the coccolith volume and the particulate inorganic carbon production. The conducted experiments revealed that the coccolith volume of E. huxleyi is variable with aquatic CO2 concentration but its sensitivity is rather small in comparison with its sensitivity to nitrogen limitation. Comparing coccolith morphological and geometrical parameters like volume, mass and size to physiological parameters under controlled laboratory conditions is an important step to understand variations in fossil coccolith geometry.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2014-02-11.
description: Supplement to: Müller, Marius N; Beaufort, Luc; Bernard, O; Pedrotti, Maria Luiza; Talec, A; Sciandra, Antoine (2012): Influence of CO2 and nitrogen limitation on the coccolith volume of Emiliania huxleyi (Haptophyta). Biogeosciences, 9(10), 4155-4167
DOI: 10.1594/pangaea.736024
title: Seawater carbonate chemistry and processes during experiments with cyanobacterium Trichodesmium (IMS101), 2009

description: We investigated carbon acquisition by the N2-fixing cyanobacterium Trichodesmium IMS101 in response to CO2 levels of 15.1, 37.5, and 101.3 Pa (equivalent to 150, 370, and 1000 ppm). In these acclimations, growth rates as well as cellular C and N contents were measured. In vivo activities of carbonic anhydrase (CA), photosynthetic O2 evolution, and CO2 and HCO3- fluxes were measured using membrane inlet mass spectrometry and the 14C disequilibrium technique. While no differences in growth rates were observed, elevated CO2 levels caused higher C and N quotas and stimulated photosynthesis and N2 fixation. Minimal extracellular CA (eCA) activity was observed, indicating a minor role in carbon acquisition. Rates of CO2 uptake were small relative to total inorganic carbon (Ci) fixation, whereas HCO{3 contributed more than 90% and varied only slightly over the light period and between CO2 treatments. The low eCA activity and preference for HCO3- were verified by the 14C disequilibrium technique. Regarding apparent affinities, half-saturation concentrations (K1/2) for photosynthetic O2 evolution and HCO3- uptake changed markedly over the day and with CO2 concentration. Leakage (CO2 efflux : Ci uptake) showed pronounced diurnal changes. Our findings do not support a direct CO2 effect on the carboxylation efficiency of ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) but point to a shift in resource allocation among photosynthesis, carbon acquisition, and N2 fixation under elevated CO2 levels. The observed increase in photosynthesis and N2fixation could have potential biogeochemical implications, as it may stimulate productivity in N-limited oligotrophic regions and thus provide a negative feedback in rising atmospheric CO2 levels.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Lavigne and Gattuso, 2011) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI).
description: Supplement to: Kranz, Sven A; Sültemeyer, Dieter; Richter, Klaus-Uwe; Rost, Björn (2009): Carbon acquisition by Trichodesmium: the effect of pCO2 and diurnal changes. Limnology and Oceanography, 54(2), 548-559
DOI: 10.1594/pangaea.973011
title: Carbon and nitrogen concentrations alongside stable isotopes of the sediment core segment EN20001_6 from Lake Khamra, Yakutia, Siberia

description: The data contains biogeochemical data, including total carbon and nitrogen concentrations, as well as stable carbon (δ13C) and nitrogen isotopes (δ15N) of 21 samples from the core segment EN20001_6. All measurements were carried out at AWI Potsdam. TOC was analysed by using an Elementar soli TOC cube, whereas TN was quantified by an Elementar rapid MAX N exceed. The measurement accuracy was 0.1 % for both devices. We computed the total carbon (TC) by the sum of TOC and the total inorganic carbon (TIC). Furthermore, we calculated the TOC/TN atomic ratio by multiplying its mass ratio by 1.167, which is the ratio of the atomic weights of nitrogen and carbon (Meyers and Teranes, 2001). Carbon and nitrogen isotopes (δ13C,δ15N) were determined using a ThermoFisher Scientific Delta‐V‐Advantage gas‐mass spectrometer equipped with a FLASH elemental analyser EA 2000 and a CONFLO IV gas‐mixing system and an MA200R autosampler system at ISOLAB of AWI Potsdam. We removed inorganic carbon by a hydrochloric acid treatment (HCl, 1.3 mol L-1) prior carbon isotope. Isotope ratios are given relative to laboratory standards of known isotopic compositions relative to the Vienna Pee Dee Belemnite (VPDB) reference standard for carbon and to the standard atmospheric nitrogen ratio (air) for nitrogen. Results are given as delta notation (δ13C, δ15N) in per mill (‰), with 1σ standard error better than ±0.15 ‰.
DOI: 10.1594/pangaea.961012
title: Seawater carbonate chemistry and photosynthetic performance and N2 fixation in the marine cyanobacterium Trichodesmium

description: Effects of changed levels of dissolved O2 and CO2 on marine primary producers are of general concern with respect to ecological effects of ongoing ocean deoxygenation and acidification as well as upwelled seawaters. We investigated the response of the diazotroph Trichodesmium erythraeum IMS 101 after it had acclimated to lowered pO2 (~60 μM O2) and/or elevated pCO2 levels (HC, ~32 μM CO2) for about 20 generations. Our results showed that reduced O2 levels decreased dark respiration significantly, and increased the net photosynthetic rate by 66 and 89% under the ambient (AC, ~13 μM CO2) and the HC, respectively. The reduced pO2 enhanced the N2 fixation rate by ~139% under AC and only by 44% under HC, respectively. The N2 fixation quotient, the ratio of N2 fixed per O2 evolved, increased by 143% when pO2 decreased by 75% under the elevated pCO2. Meanwhile, particulate organic carbon and nitrogen quota increased simultaneously under reduced O2 levels, regardless of the pCO2 treatments. Nevertheless, changed levels of O2 and CO2 did not bring about significant changes in the specific growth rate of the diazotroph. Such inconsistency was attributed to the daytime positive and nighttime negative effects of both lowered pO2 and elevated pCO2 on the energy supply for growth. Our results suggest that Trichodesmium decrease its dark respiration by 5% and increase its N2-fixation by 49% and N2-fixation quotient by 30% under future ocean deoxygenation and acidification with 16% decline of pO2 and 138% rise of pCO2 by the end of this century.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2022) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2023-07-19.
DOI: 10.1594/pangaea.950700
title: Seawater carbonate chemistry and growth, production and nitrogen cycling of Nodularia spumigena

description: Heterocystous cyanobacteria of the genus Nodularia form extensive blooms in the Baltic Sea and contribute substantially to the total annual primary production. Moreover, they dispense a large fraction of new nitrogen to the ecosystem when inorganic nitrogen concentration in summer is low. Thus, it is of ecological importance to know how Nodularia will react to future environmental changes, in particular to increasing carbon dioxide (CO2) concentrations and what consequences there might arise for cycling of organic matter in the Baltic Sea. Here, we determined carbon (C) and dinitrogen (N2) fixation rates, growth, elemental stoichiometry of particulate organic matter and nitrogen turnover in batch cultures of the heterocystous cyanobacterium Nodularia spumigena under low (median 315 μatm), mid (median 353 μatm), and high (median 548 μatm) CO2 concentrations. Our results demonstrate an overall stimulating effect of rising pCO2 on C and N2 fixation, as well as on cell growth. An increase in pCO2 during incubation days 0 to 9 resulted in an elevation in growth rate by 84 ± 38% (low vs. high pCO2) and 40 ± 25% (mid vs. high pCO2), as well as in N2 fixation by 93 ± 35% and 38 ± 1%, respectively. C uptake rates showed high standard deviations within treatments and in between sampling days. Nevertheless, C fixation in the high pCO2 treatment was elevated compared to the other two treatments by 97% (high vs. low) and 44% (high vs. mid) at day 0 and day 3, but this effect diminished afterwards. Additionally, elevation in carbon to nitrogen and nitrogen to phosphorus ratios of the particulate biomass formed (POC : POP and PON : POP) was observed at high pCO2. Our findings suggest that rising pCO2 stimulates the growth of heterocystous diazotrophic cyanobacteria, in a similar way as reported for the non-heterocystous diazotroph Trichodesmium. Implications for biogeochemical cycling and food web dynamics, as well as ecological and socio-economical aspects in the Baltic Sea are discussed.
description: In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2021) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2022-11-15.