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  • 1
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    PANGAEA
    In:  Supplement to: Mackinder, Luke C M; Wheeler, Glen; Schroeder, Declan C; von Dassow, P; Riebesell, Ulf; Brownlee, Colin (2011): Expression of biomineralization-related ion transport genes in Emiliania huxleyi. Environmental Microbiology, 13(12), 3250-3265, https://doi.org/10.1111/j.1462-2920.2011.02561.x
    Publication Date: 2020-01-17
    Description: Biomineralization in the marine phytoplankton Emiliania huxleyi is a stringently controlled intracellular process. The molecular basis of coccolith production is still relatively unknown although its importance in global biogeochemical cycles and varying sensitivity to increased pCO2 levels has been well documented. This study looks into the role of several candidate Ca2+, H+ and inorganic carbon transport genes in E. huxleyi, using quantitative reverse transcriptase PCR. Differential gene expression analysis was investigated in two isogenic pairs of calcifying and non-calcifying strains of E. huxleyi and cultures grown at various Ca2+ concentrations to alter calcite production. We show that calcification correlated to the consistent upregulation of a putative HCO3- transporter belonging to the solute carrier 4 (SLC4) family, a Ca2+/H+ exchanger belonging to the CAX family of exchangers and a vacuolar H+-ATPase. We also show that the coccolith-associated protein, GPA is downregulated in calcifying cells. The data provide strong evidence that these genes play key roles in E. huxleyi biomineralization. Based on the gene expression data and the current literature a working model for biomineralization-related ion transport in coccolithophores is presented.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 2
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    PANGAEA
    In:  GEOMAR - Helmholtz Centre for Ocean Research Kiel | Supplement to: Bach, Lennart Thomas; Riebesell, Ulf; Gutowska, Magdalena A; Federwisch, Luisa; Schulz, Kai Georg (2015): A unifying concept of coccolithophore sensitivity to changing carbonate chemistry embedded in an ecological framework. Progress in Oceanography, 135, 125-138, https://doi.org/10.1016/j.pocean.2015.04.012
    Publication Date: 2020-01-17
    Description: Coccolithophores are a group of unicellular phytoplankton species whose ability to calcify has a profound influence on biogeochemical element cycling. Calcification rates are controlled by a large variety of biotic and abiotic factors. Among these factors, carbonate chemistry has gained considerable attention during the last years as coccolithophores have been identified to be particularly sensitive to ocean acidification. Despite intense research in this area, a general concept harmonizing the numerous and sometimes (seemingly) contradictory responses of coccolithophores to changing carbonate chemistry is still lacking to date. Here, we present the "substrate-inhibitor concept" which describes the dependence of calcification rates on carbonate chemistry speciation. It is based on observations that calcification rate scales positively with bicarbonate (HCO3-), the primary substrate for calcification, and carbon dioxide (CO2), which can limit cell growth, whereas it is inhibited by protons (H+). This concept was implemented in a model equation, tested against experimental data, and then applied to understand and reconcile the diverging responses of coccolithophorid calcification rates to ocean acidification obtained in culture experiments. Furthermore, we (i) discuss how other important calcification-influencing factors (e.g. temperature and light) could be implemented in our concept and (ii) embed it in Hutchinson's niche theory, thereby providing a framework for how carbonate chemistry-induced changes in calcification rates could be linked with changing coccolithophore abundance in the oceans. Our results suggest that the projected increase of H+ in the near future (next couple of thousand years), paralleled by only a minor increase of inorganic carbon substrate, could impede calcification rates if coccolithophores are unable to fully adapt. However, if calcium carbonate (CaCO3) sediment dissolution and terrestrial weathering begin to increase the oceans' HCO3- and decrease its H+ concentrations in the far future (10 -100 kyears), coccolithophores could find themselves in carbonate chemistry conditions which may be more favorable for calcification than they were before the Anthropocene.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 3
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    PANGAEA
    In:  Environmental and Marine Biology, Åbo Akademi University | Supplement to: Almén, Anna-Karin; Brutemark, Andreas; Jutfelt, Fredrik; Riebesell, Ulf; Engström-Öst, Jonna (2017): Ocean acidification causes no detectable effect on swimming activity and body size in a common copepod. Hydrobiologia, 802(1), 235-243, https://doi.org/10.1007/s10750-017-3273-5
    Publication Date: 2020-01-17
    Description: Ocean acidification can impair an animal's physiological performance and energetically demand- ing activities such as swimming. Behavioural abnor- malities and changed activity in response to ocean acidification are reported in fish and crustacean species. We studied swimming activity in the calanoid copepod Pseudocalanus acuspes in response to near- future ocean acidification. Water and copepods were sampled from ten mesocosms deployed on the Swedish west coast. The experiments were conducted on animals reared in the mesocosms for 2 months during spring. Copepods were filmed after long-term (chronic) high-CO2, and after 20 h acute exposure to CO2. There was no significant effect of CO2 on copepods in chronic high-CO2, nor significant effect after the 20 h acute exposure. In addition, we measured prosome length from a large number of adult copepods, but no effect of acidification on body size was found. In this study, P. acuspes did not show sensitivity to near-future pCO2 levels. Even if a number of papers suggest that copepods seem robust to future ocean acidification, interaction between multiple stress factors, such as elevated temperature, hypoxia and salinity changes may impair a copepod's ability to resist lowered pH.
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 4
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    PANGAEA
    In:  Supplement to: Horn, Henriette G; Sander, Nils; Stuhr, Annegret; Algueró-Muñiz, Maria; Bach, Lennart Thomas; Löder, Martin G J; Boersma, Maarten; Riebesell, Ulf; Aberle, Nicole (2016): Low CO2 Sensitivity of Microzooplankton Communities in the Gullmar Fjord, Skagerrak: Evidence from a Long-Term Mesocosm Study. PLoS ONE, 11(11), e0165800, https://doi.org/10.1371/journal.pone.0165800
    Publication Date: 2020-01-17
    Description: Ocean acidification is considered as a crucial stressor for marine communities. In this study, we tested the effects of the IPCC RPC6.0 end-of-century acidification scenario on a natural plankton community in the Gullmar Fjord, Sweden, during a long-term mesocosm experiment from a spring bloom to a mid-summer situation. The focus of this study was on microzooplankton and its interactions with phytoplankton and mesozooplankton. The microzooplankton community was dominated by ciliates, especially small Strombidium sp., with the exception of the last days when heterotrophic dinoflagellates increased in abundance. We did not observe any effects of high CO2 on the community composition and diversity of microzooplankton. While ciliate abundance, biomass and growth rate were not affected by elevated CO2, we observed a positive effect of elevated CO2 on dinoflagellate abundances. Additionally, growth rates of dinoflagellates were significantly higher in the high CO2 treatments. Given the higher Chlorophyll a content measured under high CO2, our results point at mainly indirect effects of CO2 on microzooplankton caused by changes in phytoplankton standing stocks, in this case most likely an increase in small-sized phytoplankton of 〈8 µm. Overall, the results from the present study covering the most important part of the growing season indicate that coastal microzooplankton communities are rather robust towards realistic acidification scenarios.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 5
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    PANGAEA
    In:  Supplement to: Bach, Lennart Thomas; Hernandez-Hernandez, Nauzet; Taucher, Jan; Spisla, Carsten; Sforna, Claudia; Riebesell, Ulf; Aristegui, J (2019): Effects of Elevated CO2 on a Natural Diatom Community in the Subtropical NE Atlantic. Frontiers in Marine Science, 6, https://doi.org/10.3389/fmars.2019.00075
    Publication Date: 2020-01-17
    Description: Diatoms are silicifying phytoplankton contributing about one quarter to primary 79 production on Earth. Ocean acidification (OA) could alter the competitiveness of diatoms 80 relative to other taxa and/or lead to shifts among diatom species. In spring 2016, we set 81 up a plankton community experiment at the coast of Gran Canaria (Canary Islands, 82 Spain) to investigate the response of subtropical diatom assemblages to elevated 83 84 seawater pCO2.
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 6
  • 7
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 1130 data points
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  • 8
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 284 data points
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  • 9
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    PANGAEA
    In:  Supplement to: Bach, Lennart Thomas; Riebesell, Ulf; Sett, Scarlett; Febin, Sarah; Rzepka, Paul; Schulz, Kai Georg (2012): An approach for particle sinking velocity measurements in the 3–400 µm size range and considerations on the effect of temperature on sinking rates. Marine Biology, 159(8), 1853-1864, https://doi.org/10.1007/s00227-012-1945-2
    Publication Date: 2020-01-17
    Description: The flux of organic particles below the mixed layer is one major pathway of carbon from the surface into the deep ocean. The magnitude of this export flux depends on two major processes--remineralization rates and sinking velocities. Here, we present an efficient method to measure sinking velocities of particles in the size range from approximately 3-400 µm by means of video microscopy (FlowCAM®). The method allows rapid measurement and automated analysis of mixed samples and was tested with polystyrene beads, different phytoplankton species, and sediment trap material. Sinking velocities of polystyrene beads were close to theoretical values calculated from Stokes' Law. Sinking velocities of the investigated phytoplankton species were in reasonable agreement with published literature values and sinking velocities of material collected in sediment trap increased with particle size. Temperature had a strong effect on sinking velocities due to its influence on seawater viscosity and density. An increase in 9 °C led to a measured increase in sinking velocities of 40 %. According to this temperature effect, an average temperature increase in 2 °C as projected for the sea surface by the end of this century could increase sinking velocities by about 6 % which might have feedbacks on carbon export into the deep ocean.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 10
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    PANGAEA
    In:  GEOMAR - Helmholtz Centre for Ocean Research Kiel | Supplement to: Engel, Anja; Piontek, Judith; Grossart, Hans-Peter; Riebesell, Ulf; Schulz, Kai Georg; Sperling, Martin (2014): Impact of CO2 enrichment on organic matter dynamics during nutrient induced coastal phytoplankton blooms. Journal of Plankton Research, 36(3), 641-657, https://doi.org/10.1093/plankt/fbt125
    Publication Date: 2020-01-17
    Description: A mesocosm experiment was conducted to investigate the impact of rising fCO2 on the build-up and decline of organic matter during coastal phytoplankton blooms. Five mesocosms (~38 m³ each) were deployed in the Baltic Sea during spring (2009) and enriched with CO2 to yield a gradient of 355-862 µatm. Mesocosms were nutrient fertilized initially to induce phytoplankton bloom development. Changes in particulate and dissolved organic matter concentrations, including dissolved high-molecular weight (〉1 kDa) combined carbohydrates, dissolved free and combined amino acids as well as transparent exopolymer particles (TEP), were monitored over 21 days together with bacterial abundance, and hydrolytic extracellular enzyme activities. Overall, organic matter followed well-known bloom dynamics in all CO2 treatments alike. At high fCO2, higher dPOC:dPON during bloom rise, and higher TEP concentrations during bloom peak, suggested preferential accumulation of carbon-rich components. TEP concentration at bloom peak was significantly related to subsequent sedimentation of particulate organic matter. Bacterial abundance increased during the bloom and was highest at high fCO2. We conclude that increasing fCO2 supports production and exudation of carbon-rich components, enhancing particle aggregation and settling, but also providing substrate and attachment sites for bacteria. More labile organic carbon and higher bacterial abundance can increase rates of oxygen consumption and may intensify the already high risk of oxygen depletion in coastal seas in the future.
    Type: Dataset
    Format: application/zip, 2 datasets
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