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  • 11
    Online Resource
    Online Resource
    Temporal dynamics of surface ocean carbonate chemistry in response to natural and simulated upwelling events during the 2017 coastal El Niño near Callao, Peru
    Copernicus GmbH ; 2022
    In:  Biogeosciences Vol. 19, No. 2 ( 2022-01-19), p. 295-312
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 19, No. 2 ( 2022-01-19), p. 295-312
    Abstract: Abstract. Oxygen minimum zones (OMZs) are characterized by enhanced carbon dioxide (CO2) levels and low pH and are being further acidified by uptake of anthropogenic atmospheric CO2. With ongoing intensification and expansion of OMZs due to global warming, carbonate chemistry conditions may become more variable and extreme, particularly in the eastern boundary upwelling systems. In austral summer (February–April) 2017, a large-scale mesocosm experiment was conducted in the coastal upwelling area off Callao (Peru) to investigate the impacts of ongoing ocean deoxygenation on biogeochemical processes, coinciding with a rare coastal El Niño event. Here we report on the temporal dynamics of carbonate chemistry in the mesocosms and surrounding Pacific waters over a continuous period of 50 d with high-temporal-resolution observations (every second day). The mesocosm experiment simulated an upwelling event in the mesocosms by addition of nitrogen (N)-deficient and CO2-enriched OMZ water. Surface water in the mesocosms was acidified by the OMZ water addition, with pHT lowered by 0.1–0.2 and pCO2 elevated to above 900 µatm. Thereafter, surface pCO2 quickly dropped to near or below the atmospheric level (405.22 µatm in 2017; Dlugokencky and Tans, 2021; NOAA/Global Monitoring Laboratory (GML)) mainly due to enhanced phytoplankton production with rapid CO2 consumption. Further observations revealed that the dominance of the dinoflagellate Akashiwo sanguinea and contamination of bird excrements played important roles in the dynamics of carbonate chemistry in the mesocosms. Compared to the simulated upwelling, natural upwelling events in the surrounding Pacific waters occurred more frequently with sea-to-air CO2 fluxes of 4.2–14.0 mmol C m−2 d−1. The positive CO2 fluxes indicated our site was a local CO2 source during our study, which may have been impacted by the coastal El Niño. However, our observations of dissolved inorganic carbon (DIC) drawdown in the mesocosms suggest that CO2 fluxes to the atmosphere can be largely dampened by biological processes. Overall, our study characterized carbonate chemistry in nearshore Pacific waters that are rarely sampled in such a temporal resolution and hence provided unique insights into the CO2 dynamics during a rare coastal El Niño event.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-19-295-2022
    DOI: 10.5194/bg-19-295-2022-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2022
    detail.hit.zdb_id: 2158181-2
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  • 12
    Online Resource
    Online Resource
    Effects of CO〈sub〉2〈/sub〉 perturbation on phosphorus pool sizes and uptake in a mesocosm experiment during a low productive summer season in the northern Baltic Sea
    Copernicus GmbH ; 2016
    In:  Biogeosciences Vol. 13, No. 10 ( 2016-05-24), p. 3035-3050
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 13, No. 10 ( 2016-05-24), p. 3035-3050
    Abstract: Abstract. Studies investigating the effect of increasing CO2 levels on the phosphorus cycle in natural waters are lacking although phosphorus often controls phytoplankton development in many aquatic systems. The aim of our study was to analyse effects of elevated CO2 levels on phosphorus pool sizes and uptake. The phosphorus dynamic was followed in a CO2-manipulation mesocosm experiment in the Storfjärden (western Gulf of Finland, Baltic Sea) in summer 2012 and was also studied in the surrounding fjord water. In all mesocosms as well as in surface waters of Storfjärden, dissolved organic phosphorus (DOP) concentrations of 0.26 ± 0.03 and 0.23 ± 0.04 µmol L−1, respectively, formed the main fraction of the total P-pool (TP), whereas phosphate (PO4) constituted the lowest fraction with mean concentration of 0.15 ± 0.02 in the mesocosms and 0.17 ± 0.07 µmol L−1 in the fjord. Transformation of PO4 into DOP appeared to be the main pathway of PO4 turnover. About 82 % of PO4 was converted into DOP whereby only 18 % of PO4 was transformed into particulate phosphorus (PP). PO4 uptake rates measured in the mesocosms ranged between 0.6 and 3.9 nmol L−1 h−1. About 86 % of them was realized by the size fraction 〈 3 µm. Adenosine triphosphate (ATP) uptake revealed that additional P was supplied from organic compounds accounting for 25–27 % of P provided by PO4 only. CO2 additions did not cause significant changes in phosphorus (P) pool sizes, DOP composition, and uptake of PO4 and ATP when the whole study period was taken into account. However, significant short-term effects were observed for PO4 and PP pool sizes in CO2 treatments 〉 1000 µatm during periods when phytoplankton biomass increased. In addition, we found significant relationships (e.g., between PP and Chl a) in the untreated mesocosms which were not observed under high fCO2 conditions. Consequently, it can be hypothesized that the relationship between PP formation and phytoplankton growth changed with CO2 elevation. It can be deduced from the results, that visible effects of CO2 on P pools are coupled to phytoplankton growth when the transformation of PO4 into POP was stimulated. The transformation of PO4 into DOP on the other hand does not seem to be affected. Additionally, there were some indications that cellular mechanisms of P regulation might be modified under CO2 elevation changing the relationship between cellular constituents.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    DOI: 10.5194/bg-13-3035-2016
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2158181-2
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  • 13
    Online Resource
    Online Resource
    Exploring the distance between nitrogen and phosphorus limitation in mesotrophic surface waters using a sensitive bioassay
    Copernicus GmbH ; 2017
    In:  Biogeosciences Vol. 14, No. 2 ( 2017-01-25), p. 379-387
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 14, No. 2 ( 2017-01-25), p. 379-387
    Abstract: Abstract. The balance in microbial net consumption of nitrogen and phosphorus was investigated in samples collected in two mesotrophic coastal environments: the Baltic Sea (Tvärminne field station) and the North Sea (Espegrend field station). For this, we have refined a bioassay based on the response in alkaline phosphatase activity (APA) over a matrix of combinations in nitrogen and phosphorus additions. This assay not only provides information on which element (N or P) is the primary limiting nutrient, but also gives a quantitative estimate for the excess of the secondary limiting element (P+ or N+, respectively), as well as the ratio of balanced net consumption of added N and P over short timescales (days). As expected for a Baltic Sea late spring–early summer situation, the Tvärminne assays (n =  5) indicated N limitation with an average P+ =  0.30 ± 0.10 µM-P, when incubated for 4 days. For short incubations (1–2 days), the Espegrend assays indicated P limitation, but the shape of the response surface changed with incubation time, resulting in a drift in parameter estimates toward N limitation. Extrapolating back to zero incubation time gave P limitation with N+ ≈  0.9 µM-N. The N : P ratio (molar) of nutrient net consumption varied considerably between investigated locations: from 2.3 ± 0.4 in the Tvärminne samples to 13 ± 5 and 32 ± 3 in two samples from Espegrend. Our assays included samples from mesocosm acidification experiments, but statistically significant effects of ocean acidification were not found by this method.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-14-379-2017
    DOI: 10.5194/bg-14-379-2017-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2017
    detail.hit.zdb_id: 2158181-2
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  • 14
    Online Resource
    Online Resource
    Can morphological features of coccolithophores serve as a reliable proxy to reconstruct environmental conditions of the past?
    Copernicus GmbH ; 2020
    In:  Climate of the Past Vol. 16, No. 3 ( 2020-06-09), p. 1007-1025
    Details
    In: Climate of the Past, Copernicus GmbH, Vol. 16, No. 3 ( 2020-06-09), p. 1007-1025
    Abstract: Abstract. Morphological changes in coccoliths, tiny calcite platelets covering the outer surface of coccolithophores, can be induced by physiological responses to environmental changes. Coccoliths recovered from sedimentary successions may therefore provide information on paleo-environmental conditions prevailing at the time when the coccolithophores were alive. To calibrate the biomineralization responses of ancient coccolithophore to environmental changes, studies often compared the biological responses of living coccolithophore species with paleo-data from calcareous nannofossils. However, there is uncertainty whether the morphological responses of living coccolithophores are representative of those of the fossilized ancestors. To investigate this, we exposed four living coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica, Coccolithus pelagicus subsp. braarudii, and Pleurochrysis carterae) that have been evolutionarily distinct for hundreds of thousands to millions of years, to a range of environmental conditions (i.e., changing light intensity, Mg∕Ca ratio, nutrient availability, temperature, and carbonate chemistry) and evaluated their responses in coccolith morphology (i.e., size, length, width, malformation). The motivation for this study was to test if there is a consistent morphological response of the four species to changes in any of the tested abiotic environmental factors. If this was the case, then this could suggest that coccolith morphology can serve as a paleo-proxy for that specific factor because this response is conserved across species that have been evolutionary distinct over geological timescales. However, we found that the four species responded differently to changing light intensity, Mg∕Ca ratio, nutrient availability, and temperature in terms of coccolith morphology. The lack of a common response reveals the difficulties in using coccolith morphology as a paleo-proxy for these environmental drivers. However, a common response was observed under changing seawater carbonate chemistry (i.e., rising CO2), which consistently induced malformations. This commonality provides some confidence that malformations found in the sedimentary record could be indicative of adverse carbonate chemistry conditions.
    Type of Medium: Online Resource
    ISSN: 1814-9332
    URL: Article
    URL: Article
    DOI: 10.5194/cp-16-1007-2020
    DOI: 10.5194/cp-16-1007-2020-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2020
    detail.hit.zdb_id: 2217985-9
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  • 15
    Online Resource
    Online Resource
    Coccolith strontium to calcium ratios in Emiliania huxleyi: The dependence on seawater strontium and calcium concentrations
    Wiley ; 2006
    In:  Limnology and Oceanography Vol. 51, No. 1 ( 2006-01), p. 310-320
    Details
    In: Limnology and Oceanography, Wiley, Vol. 51, No. 1 ( 2006-01), p. 310-320
    Type of Medium: Online Resource
    ISSN: 0024-3590
    URL: Article
    DOI: 10.4319/lo.2006.51.1.0310
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 16
    Online Resource
    Online Resource
    Changes in primary productivity and chlorophyll a in response to iron fertilization in the Southern Polar Frontal Zone
    Wiley ; 2002
    In:  Limnology and Oceanography Vol. 47, No. 5 ( 2002-09), p. 1324-1335
    Details
    In: Limnology and Oceanography, Wiley, Vol. 47, No. 5 ( 2002-09), p. 1324-1335
    Type of Medium: Online Resource
    ISSN: 0024-3590
    URL: Article
    DOI: 10.4319/lo.2002.47.5.1324
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 17
    Online Resource
    Online Resource
    Effect of phosphorus limitation on elemental composition and stable carbon isotope fractionation in a marine diatom growing under different CO2 concentrations
    Wiley ; 2001
    In:  Limnology and Oceanography Vol. 46, No. 3 ( 2001-05), p. 497-504
    Details
    In: Limnology and Oceanography, Wiley, Vol. 46, No. 3 ( 2001-05), p. 497-504
    Abstract: Blooms of the marine diatom Skeletonema costatum were initiated in closed‐system batch cultures with P‐deficient medium under two different initial concentrations of dissolved molecular CO 2 ([CO 2,aq ]: 20.6 and 4.5 µmol L −1 ). Algal C: N: P ratios strongly increased with decreasing P concentration. In the exponential growth phase, C: N ratios were 1.3 mol mol −1 higher in the low relative to the high [CO 2,aq ] treatment. There was no [CO 2,aq ] effect on C: N: P ratios during P‐limited growth. Carbon isotope fractionation (Âɛp ) was 2–3‰ higher in the high [CO 2,aq ] treatment. With growth rate decreasing due to P limitation, e p increased in both [CO 2,aq ] treatments by 2ߝ3‰ despite decreasing [CO 2,aq ]. Under these conditions the effect of decreasing growth rate on isotope fractionation strongly dominated over that of declining CO 2 availability. When extrapolated to the natural environment, these results imply that systematic changes in algal growth, as occurring during the course of phytoplankton blooms, may affect algal isotope fractionation. These results severely complicate the interpretation of carbon isotope measurements in suspended and sedimentary organic matter.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Article
    DOI: 10.4319/lo.2001.46.3.0497
    Language: English
    Publisher: Wiley
    Publication Date: 2001
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 18
    Online Resource
    Online Resource
    Testing the effect of CO2 concentration on the dynamics of marine heterotrophic bacterioplankton
    Wiley ; 2006
    In:  Limnology and Oceanography Vol. 51, No. 1 ( 2006-01), p. 1-11
    Details
    In: Limnology and Oceanography, Wiley, Vol. 51, No. 1 ( 2006-01), p. 1-11
    Type of Medium: Online Resource
    ISSN: 0024-3590
    URL: Article
    DOI: 10.4319/lo.2006.51.1.0001
    Language: English
    Publisher: Wiley
    Publication Date: 2006
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 19
    Online Resource
    Online Resource
    Between‐ and within‐population variations in thermal reaction norms of the coccolithophore Emiliania huxleyi
    Wiley ; 2014
    In:  Limnology and Oceanography Vol. 59, No. 5 ( 2014-09), p. 1570-1580
    Details
    In: Limnology and Oceanography, Wiley, Vol. 59, No. 5 ( 2014-09), p. 1570-1580
    Abstract: Thermal reaction norms for growth rates of six Emiliania huxleyi isolates originating from the central Atlantic (Azores, Portugal) and five isolates from the coastal North Atlantic (Bergen, Norway) were assessed. We used the template mode of variation model to decompose variations in growth rates into modes of biological interest: vertical shift, horizontal shift, and generalist—specialist variation. In line with the actual habitat conditions, isolates from Bergen (Bergen population) grew well at lower temperatures, and isolates from the Azores (Azores population) performed better at higher temperatures. The optimum growth temperature of the Azores population was significantly higher than that of the Bergen population. Neutral genetic differentiation was found between populations by microsatellite analysis. These findings indicate that E. huxleyi populations are adapted to local temperature regimes. Next to between‐population variation, we also found variation within populations. Genotype‐by‐environment interactions resulted in the most pronounced phenotypic differences when isolates were exposed to temperatures outside the range they naturally encounter. Variation in thermal reaction norms between and within populations emphasizes the importance of using more than one isolate when studying the consequences of global change on marine phytoplankton. Phenotypic plasticity and standing genetic variation will be important in determining the potential of natural E. huxleyi populations to cope with global climate change.
    Type of Medium: Online Resource
    ISSN: 0024-3590 , 1939-5590
    URL: Article
    DOI: 10.4319/lo.2014.59.5.1570
    Language: English
    Publisher: Wiley
    Publication Date: 2014
    detail.hit.zdb_id: 2033191-5
    detail.hit.zdb_id: 412737-7
    SSG: 12
    SSG: 14
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  • 20
    Online Resource
    Online Resource
    Ocean acidification increases the accumulation of toxic phenolic compounds across trophic levels
    Springer Science and Business Media LLC ; 2015
    In:  Nature Communications Vol. 6, No. 1 ( 2015-10-27)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 6, No. 1 ( 2015-10-27)
    Abstract: Increasing atmospheric CO 2 concentrations are causing ocean acidification (OA), altering carbonate chemistry with consequences for marine organisms. Here we show that OA increases by 46–212% the production of phenolic compounds in phytoplankton grown under the elevated CO 2 concentrations projected for the end of this century, compared with the ambient CO 2 level. At the same time, mitochondrial respiration rate is enhanced under elevated CO 2 concentrations by 130–160% in a single species or mixed phytoplankton assemblage. When fed with phytoplankton cells grown under OA, zooplankton assemblages have significantly higher phenolic compound content, by about 28–48%. The functional consequences of the increased accumulation of toxic phenolic compounds in primary and secondary producers have the potential to have profound consequences for marine ecosystem and seafood quality, with the possibility that fishery industries could be influenced as a result of progressive ocean changes.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/ncomms9714
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2015
    detail.hit.zdb_id: 2553671-0
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