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| Titel |
Impact of seawater carbonate chemistry on the calcification of marine bivalves |
| VerfasserIn |
J. Thomsen, K. Haynert, K. M. Wegner, F. Melzner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 14 ; Nr. 12, no. 14 (2015-07-17), S.4209-4220 |
| Datensatznummer |
250118024
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| Publikation (Nr.) |
 copernicus.org/bg-12-4209-2015.pdf |
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| Zusammenfassung |
| Bivalve calcification, particularly of the early larval stages, is highly
sensitive to the change in ocean carbonate chemistry resulting from
atmospheric CO2 uptake. Earlier studies suggested that declining
seawater [CO32−] and thereby lowered carbonate saturation affect
shell production. However, disturbances of physiological processes such as
acid-base regulation by adverse seawater pCO2 and pH can affect
calcification in a secondary fashion. In order to determine the exact
carbonate system component by which growth and calcification are affected it
is necessary to utilize more complex carbonate chemistry manipulations. As
single factors, pCO2 had no effects and [HCO3-] and pH had only limited
effects on shell growth, while lowered [CO32−] strongly impacted
calcification. Dissolved inorganic carbon (CT) limiting conditions led
to strong reductions in calcification, despite high [CO32−],
indicating that [HCO3-] rather than [CO32−] is the
inorganic carbon source utilized for calcification by mytilid mussels.
However, as the ratio [HCO3-] / [H+] is linearly correlated
with [CO32−] it is not possible to differentiate between these
under natural seawater conditions. An equivalent of about 80 μmol kg−1 [CO32−] is required to saturate inorganic carbon supply
for calcification in bivalves. Below this threshold biomineralization rates
rapidly decline. A comparison of literature data available for larvae and
juvenile mussels and oysters originating from habitats differing
substantially with respect to prevailing carbonate chemistry conditions
revealed similar response curves. This suggests that the mechanisms which
determine sensitivity of calcification in this group are highly conserved.
The higher sensitivity of larval calcification seems to primarily result
from the much higher relative calcification rates in early life stages. In
order to reveal and understand the mechanisms that limit or facilitate
adaptation to future ocean acidification, it is necessary to better
understand the physiological processes and their underlying genetics that
govern inorganic carbon assimilation for calcification. |
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