Dynamics of transparent exopolymeric particles and their precursors during a mesocosm experiment: Impact of ocean acidification
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Keywords:
Mesocosm
Ocean Acidification
Total inorganic carbon
Sedimentation
Ocean acidification, one of the great global environmental issues at present, is expected to result in serious damage on marine calcareous organisms such as corals and calcifying algae, which potentially release huge amounts of CO2 from the ocean to the atmosphere. The coccolithophore, Emiliania huxleyi (Haptophyceae), which frequently produces blooms, has greatly contributed to the biological CO2 pump. This study was aimed at analyzing effects of how E. huxleyi responds to acidification. Acidi- fication was performed by two methods, namely by just adding HCl under bubbling ordinary air at 8.2-8.4, 7.6-7.8 and 7.1-7.3 (acidification by HCl) and by bubbling with ordinary air or with increased CO2 concentration such as 406, 816 and 1,192 ppm that maintained pH of the medium at 8.0-8.3, 7.6-7.9 and 7.5-7.7 (acidification by CO2 enrichment). As a result, cell growth and cellular calcifi- cation of E. huxleyi were strongly damaged by acidification by HCl, but not by acidification by CO2 enrichment. The activities of photosystems such as Fv/Fm and /PSII were not affected by any acidification conditions while photo- synthetic O2 evolution was slightly stimulated. A 45 Ca- radiotracer experiment revealed that Ca 2? -uptake was strongly suppressed by acidification with HCl. This sup- pression recovered after increasing the dissolved inorganic carbon (DIC) concentration and further stimulated by an additional increase in DIC concentration. The production of storage and coccolith polysaccharides was increased by acidification by HCl and also highly stimulated by acidi- fication with CO2 enrichment. The present study clearly showed that the coccolithophore, E. huxleyi, has an ability to respond positively to acidification with CO2 enrichment, but not just acidification.
Emiliania huxleyi
Ocean Acidification
Coccolithophore
Total inorganic carbon
Coccolith
Carbonic acid
Alkalinity
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Ocean Acidification
Mariculture
Total inorganic carbon
Extreme environment
Alkalinity
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Automated carbon analyzers often are configured to provide estimates of both total organic carbon (TOC) and nonpurgeable organic carbon (NPOC). We show there can be an overestimation of total carbon in the presence of moderate to large quantities of dissolved inorganic carbon. This leads to overestimates of TOC, which is measured as the difference between total carbon and inorganic carbon. Water samples were analyzed as both TOC and NPOC on a Shimadzu TC 5050 Carbon Analyzer. The difference between TOC and NPOC increased as a function of concentrations of dissolved inorganic carbon (DIC). Water samples spiked with DIC ranging from 0 to 100 mg DIC/L also reported increased TOC as large as 8 mg C/L. Our data suggest that the Shimadzu 5050 analyzer (and by analogy other instruments that estimate TOC by difference between TC and IC) overestimates total carbon (TC) when calibrated with an organic standard as recommended by the manufacturer. The magnitude of the overestimation varies both with the amount of DIC present in the sample and the extent to which measurement efficiency of the analyzer is less than 100%. The consequences will be most severe in analysis of samples from systems spanning a large range in DIC. Time series from individual systems are less likely to be affected because the necessary large change in DIC would be detected as changes in pH or other attributes well before any change in DOC. Systems with high DIC will, however, be susceptible to even small variations in measurement efficiency.
Total inorganic carbon
Carbon fibers
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Mesocosm
Alkalinity
Ocean Acidification
Total inorganic carbon
Carbon fibers
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Mesocosm
Ocean Acidification
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Ocean Acidification
Total inorganic carbon
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Seasonal variations in inorganic carbon chemistry and associated fluxes from the Congo River were investigated at Brazzaville‐Kinshasa. Small seasonal variation in dissolved inorganic carbon (DIC) was found in contrast with discharge‐correlated changes in pH, total alkalinity (TA), carbonate species, and dissolved organic carbon (DOC). DIC was almost always greater than TA due to the importance of CO 2 *, the sum of dissolved CO 2 and carbonic acid, as a result of low pH. Organic acids in DOC contributed 11–61% of TA and had a strong titration effect on water pH and carbonate speciation. The CO 2 * and bicarbonate fluxes accounted for ~57% and 43% of the DIC flux, respectively. Congo River surface water released CO 2 at a rate of ~109 mol m −2 yr −1 . The basin‐wide DIC yield was ~8.84 × 10 4 mol km −2 yr −1 . The discharge normalized DIC flux to the ocean amounted to 3.11 × 10 11 mol yr −1 . The DOC titration effect on the inorganic carbon system may also be important on a global scale for regulating carbon fluxes in rivers.
Alkalinity
Total inorganic carbon
Bicarbonate
Carbon fibers
Carbonic acid
Genetic algorithm
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Ocean acidification, one of the great global environmental issues at present, is expected to result in serious damage on marine calcareous organisms such as corals and calcifying algae, which potentially release huge amounts of CO2 from the ocean to the atmosphere. The coccolithophore, Emiliania huxleyi (Haptophyceae), which frequently produces blooms, has greatly contributed to the biological CO2 pump. This study was aimed at analyzing effects of how E. huxleyi responds to acidification. Acidification was performed by two methods, namely by just adding HCl under bubbling ordinary air at 8.2–8.4, 7.6–7.8 and 7.1–7.3 (acidification by HCl) and by bubbling with ordinary air or with increased CO2 concentration such as 406, 816 and 1,192 ppm that maintained pH of the medium at 8.0–8.3, 7.6–7.9 and 7.5–7.7 (acidification by CO2 enrichment). As a result, cell growth and cellular calcification of E. huxleyi were strongly damaged by acidification by HCl, but not by acidification by CO2 enrichment. The activities of photosystems such as F v/F m and ϕPSII were not affected by any acidification conditions while photosynthetic O2 evolution was slightly stimulated. A 45Ca-radiotracer experiment revealed that Ca2+-uptake was strongly suppressed by acidification with HCl. This suppression recovered after increasing the dissolved inorganic carbon (DIC) concentration and further stimulated by an additional increase in DIC concentration. The production of storage and coccolith polysaccharides was increased by acidification by HCl and also highly stimulated by acidification with CO2 enrichment. The present study clearly showed that the coccolithophore, E. huxleyi, has an ability to respond positively to acidification with CO2 enrichment, but not just acidification.
Emiliania huxleyi
Ocean Acidification
Coccolithophore
Total inorganic carbon
Coccolith
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Mesocosm
Ocean Acidification
Baltic sea
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Coccolithophores are unicellular marine algae that produce biogenic calcite scales and substantially contribute to marine primary production and carbon export to the deep ocean. Ongoing ocean acidification particularly impairs calcifying organisms, mostly resulting in decreased growth and calcification. Recent studies revealed that the immediate physiological response in the coccolithophore Emiliania huxleyi to ocean acidification may be partially compensated by evolutionary adaptation, yet the underlying molecular mechanisms are currently unknown. Here, we report on the expression levels of 10 candidate genes putatively relevant to pH regulation, carbon transport, calcification and photosynthesis in E. huxleyi populations short-term exposed to ocean acidification conditions after acclimation (physiological response) and after 500 generations of high CO 2 adaptation (adaptive response). The physiological response revealed downregulation of candidate genes, well reflecting the concomitant decrease of growth and calcification. In the adaptive response, putative pH regulation and carbon transport genes were up-regulated, matching partial restoration of growth and calcification in high CO 2 -adapted populations. Adaptation to ocean acidification in E. huxleyi likely involved improved cellular pH regulation, presumably indirectly affecting calcification. Adaptive evolution may thus have the potential to partially restore cellular pH regulatory capacity and thereby mitigate adverse effects of ocean acidification.
Emiliania huxleyi
Coccolithophore
Ocean Acidification
Total inorganic carbon
Coccolith
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