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  • 1
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    Predominance of heavily calcified coccolithophores at low CaCO3 saturation during winter in the Bay of Biscay (2012)
    PANGAEA
    In:  Supplement to: Smith, Helen Elizabeth Katie; Tyrrell, Toby; Charalampopoulou, Anastasia; Dumousseaud, Cynthia; Legge, Oliver J; Birchenough, Sarah; Pettit, Laura Rachel; Garley, Rebecca; Hartman, Sue E; Hartman, Mark C; Sagoo, Navjit; Daniels, Chris J; Achterberg, Eric Pieter; Hydes, D J (2012): Predominance of heavily calcified coccolithophores at low CaCO3 saturation during winter in the Bay of Biscay. Proceedings of the National Academy of Sciences, 109(23), 8845-8849, https://doi.org/10.1073/pnas.1117508109
    Details
    Publication Date: 2024-05-22
    Description: Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO2 levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce "a transition in dominance from more to less heavily calcified coccolithophores" [Ridgwell A, et al., (2009) Biogeosciences 6:2611-2623]. A recent observational study [Beaufort L, et al., (2011) Nature 476:80-83] also suggested that coccolithophores are less calcified in more acidic conditions. We present the results of a large observational study of coccolithophore morphology in the Bay of Biscay. Samples were collected once a month for over a year, along a 1,000-km-long transect. Our data clearly show that there is a pronounced seasonality in the morphotypes of Emiliania huxleyi, the most abundant coccolithophore species. Whereas pH and CaCO3 saturation are lowest in winter, the E. huxleyi population shifts from 〈10% (summer) to 〉90% (winter) of the heavily calcified form. However, it is unlikely that the shifts in carbonate chemistry alone caused the morphotype shift. Our finding that the most heavily calcified morphotype dominates when conditions are most acidic is contrary to the earlier predictions and raises further questions about the fate of coccolithophores in a high-CO2 world.
    Keywords: Alkalinity, total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell density; Cell density, standard error; Chromista; Coast and continental shelf; Coccoliths, overcalcified; Confidence interval; Coulometric titration; Counting; DATE/TIME; Emiliania huxleyi; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Haptophyta; LATITUDE; LONGITUDE; North Atlantic; Number of measurements; OA-ICC; Ocean Acidification International Coordination Centre; Open ocean; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Phytoplankton; Potentiometric titration; Salinity; Silicate; Single species; Species; Temperate; Temperature, water; Volume
    Type: Dataset
    Format: text/tab-separated-values, 13730 data points
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    DATA PANGAEA
  • 2
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    Seasonal and inter-annual variability in nutrient supply in relation to mixing in the Bay of Biscay (2014)
    Elsevier
    In:  Deep Sea Research Part II: Topical Studies in Oceanography, 106 . pp. 68-75.
    Details
    Publication Date: 2016-01-11
    Description: A key challenge in oceanography is to capture and quantify processes that happen on short time scales, seasonal changes and inter-annual variations. To address this problem the P&O European Ferries Ltd. Ship MV Pride of Bilbao was fitted with a FerryBox from 2002 to 2010 and data returned to NOC in real time providing near continuous measurements between UK (Portsmouth) and Spain (Bilbao) of temperature, salinity, chlorophyll-fluorescence and oxygen. Additional monthly samples were collected on manned crossings. Over 6000 samples were analysed for nitrate (nitrate and nitrite) concentrations. The timing of nitrate concentration increases (with winter mixing) and decreases (with the spring bloom) are different on and off shelf and in autumn nitrate concentrations remain high on the shelf. Off shelf in the Bay of Biscay, the mixed layer depth assessed using Argo floats, was found to vary from 212 m in relatively mild winters (such as 2007/2008) to 476 m in cold winters (2009/2010). Years with deeper mixing were associated with an increase in nitrate concentrations in the surface waters (~3 μmol l−1) and the increased vertical nutrient supply resulted in higher productivity the following spring. Bloom progression could be seen through the increase in oxygen anomaly and decrease in nitrate concentrations off shelf prior to changes further north on the shelf and phytoplankton growth was initiated as shoaling begins. The full dataset demonstrates that ships of opportunity, particularly ferries with consistently repeated routes, can deliver high quality in situ measurements over large time and space scales that currently cannot be delivered in any other way.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr2.2013.09.032
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Key controls on the seasonal and interannual variations of the carbonate system and air-sea CO2 flux in the Northeast Atlantic (Bay of Biscay) (2013)
    Wiley-Blackwell
    Details
    Publication Date: 2013-01-20
    Description: [1]  Biogeochemical variations of surface water in the Northeast Atlantic (Bay of Biscay) were examined using high-frequency underway measurements combined with monthly sampling of carbon-related variables. The mechanisms controlling seasonal CO 2 variability were investigated by distinguishing the contributions of biological and physical processes to the monthly changes in dissolved inorganic carbon (DIC) and partial pressure of CO 2 (pCO 2 ). The seasonality of DIC (47–81 μ mol kg −1 ) had a single peak with a winter maximum primarily driven by vertical mixing and a summer minimum driven by spring biological removal. Non-Redfield C:N uptake was observed in the nutrient-depleted summer but not during the spring bloom. In the North Atlantic, pCO 2 seasonality shows a latitudinal transition: from the temperature-dominated oligotrophic subtropical gyre to the subpolar region where pCO 2 is dominated by changing concentrations of DIC. In the mid-latitude Bay of Biscay, the annual cycle of pCO 2 (61–75 μ atm) showed a double-peak distribution. The summer pCO 2 peak was mainly driven by temperature increase, while the winter peak resulted from the dominant effect of entrainment of subsurface water. Interannual variations of DIC were more pronounced in winter and were driven by the changes in the strength of winter mixing. Higher wintertime concentrations and seasonal amplitudes of DIC were observed in cold years when the mixed-layer depths were deeper, which appears to be associated with negative phases of the North Atlantic Oscillation. The Bay of Biscay shows a decrease of CO 2 uptake in 2008–2010 (−0.97 and −0.75 mol m −2 yr −1 ) compared to 2002–2004 (−1.47 and −1.68 mol m −2 yr −1 ).
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley-Blackwell on behalf of American Geophysical Union (AGU).
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    PAPER CURRENT
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