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| Titel |
Combined effects of light and inorganic carbon on Southern Ocean phytoplankton |
| VerfasserIn |
Astrid Hoogstraten, Klaas R. Timmermans, Hein J. W. de Baar |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048285
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| Zusammenfassung |
| Marine autotrophic organisms convert inorganic nutrients into organic matter during
primary production. Light is the essential energy source for this process. One of the
major inorganic nutrients in the oceans used in primary production is dissolved
inorganic carbon (DIC). Both light and carbon conditions are highly variable in ocean
surface waters. Light conditions can fluctuate from too high (photo-inhibition) to too
low (light limitation). Inorganic carbon in the surface ocean can decrease to very
low conditions during a large phytoplankton bloom, as has been observed notably
in the Southern Ocean. On the other hand, the upwelling of CO2 enriched deep
waters and the predicted high future CO2 concentrations may also affect marine
phytoplankton.
The combined effects of light and inorganic carbon availability were assessed in a novel
experimental set-up which was designed jointly with the workshops of the Royal
Netherlands Institute for Sea Research. In addition, a new experimental protocol was
developed. This set-up and protocol provide stable, well maintained, culture conditions.
Two different light conditions were used during the experiments, which were high
light (240 μmol photons-
m-2-
s-1) and low light (80 μmol photons-
m-2-
s-1). The
phytoplankton was exposed to three different aqueous CO2 (CO2(aq)) concentrations,
similar in both light conditions. Those concentrations were Low CO2(aq) (~ 4-8
μmol-
kg-1), Intermediate CO2(aq) (~ 10-14 μmol-
kg-1) and High CO2(aq) (~20-30
μmol-
kg-1).
Two different Southern Ocean phytoplankton species were tested: a diatom, Proboscia
alata, and a haptophyte, Phaeocystis antarctica, During the experiments the CO2(aq)
concentrations were continuously monitored by measuring total alkalinity and dissolved
inorganic carbon. A variety of parameters was sampled on a daily basis in order to monitor
growth, physiology and morphology of the phytoplankton, and the chemistry of the
cultures.
From the results of these experiments it becomes clear that the different phytoplankton
species do not respond similarly to the different experimental treatments. The effects of the
different light intensity treatments on growth, physiology and morphology of the different
species were far more significant than the effects of the different CO2(aq) conditions. |
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