 |
| Titel |
Effects of ocean acidification on calcification of symbiont-bearing reef foraminifers |
| VerfasserIn |
K. Fujita, M. Hikami, A. Suzuki, A. Kuroyanagi, K. Sakai, H. Kawahata, Y. Nojiri |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 8 ; Nr. 8, no. 8 (2011-08-04), S.2089-2098 |
| Datensatznummer |
250006072
|
| Publikation (Nr.) |
 copernicus.org/bg-8-2089-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| Ocean acidification (decreases in carbonate ion concentration and pH) in
response to rising atmospheric pCO2 is generally expected to reduce
rates of calcification by reef calcifying organisms, with potentially severe
implications for coral reef ecosystems. Large, algal symbiont-bearing
benthic foraminifers, which are important primary and carbonate producers in
coral reefs, produce high-Mg calcite shells, whose solubility can exceed
that of aragonite produced by corals, making them the "first responder" in
coral reefs to the decreasing carbonate saturation state of seawater. Here
we report results of culture experiments performed to assess the effects of
ongoing ocean acidification on the calcification of symbiont-bearing reef
foraminifers using a high-precision pCO2 control system. Living clone
individuals of three foraminiferal species (Baculogypsina sphaerulata, Calcarina gaudichaudii, and Amphisorus hemprichii) were subjected to seawater at five pCO2 levels from 260 to 970 μatm. Cultured
individuals were maintained for about 12 weeks in an indoor flow-through
system under constant water temperature, light intensity, and photoperiod.
After the experiments, the shell diameter and weight of each cultured
specimen were measured. Net calcification of B. sphaerulata and C. gaudichaudii, which secrete a hyaline
shell and host diatom symbionts, increased under intermediate levels of
pCO2 (580 and/or 770 μatm) and decreased at a higher pCO2 level
(970 μatm). Net calcification of A. hemprichii, which secretes a porcelaneous shell
and hosts dinoflagellate symbionts, tended to decrease at elevated
pCO2. Observed different responses between hyaline and porcelaneous
species are possibly caused by the relative importance of elevated
pCO2, which induces CO2 fertilization effects by algal symbionts,
versus associated changes in seawater carbonate chemistry, which decreases a
carbonate concentration. Our findings suggest that ongoing ocean
acidification might favor symbiont-bearing reef foraminifers with hyaline
shells at intermediate pCO2 levels (580 to 770 μatm) but be
unfavorable to those with either hyaline or porcelaneous shells at higher
pCO2 levels (near 1000 μatm). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|