 |
| Titel |
Ship-board experiments to determine calcification rates of Mediterranean cold-water corals under variable pCO2 conditions |
| VerfasserIn |
Conny Maier, Markus Weinbauer, Pierre Watremez, Marco Taviani, Jean-Pierre Gattuso |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250057812
|
|
|
|
|
|
| Zusammenfassung |
| Global environmental change and the rise of CO2 have been identified as a major threat to
scleractinian corals and corals reefs. General predictions are that ocean acidification will be
detrimental to reef growth and that 40 to > 80 % of present-day reefs will decline during the
next 50 years. Cold-water corals are thought to be even more affected by changes in ocean
acidification due to the fact, that their distribution is confined to deep and/or cold waters
where they are affected even sooner by the shallowing of the aragonite saturation horizon.
While the impact of global change on reef-building, tropical corals has been intensely
studied, not much is known on the response of cold-water corals. The Mediterranean Sea is
an enclosed system and can be regarded as a miniature ocean that is expected to react
faster to global change than the open ocean, which renders it a perfect study site.
At three geographically distant sites, we therefore studied calcification rates of
three species of Mediterranean cold-water scleractinian corals directly on board
research vessels and immediately after collection. Corals were incubated directly
onboard in vials using ambient seawater under ambient, reduced or enriched pCO2 and
calcification rates were determined by the TA anomaly technique. Calcification rates
ranged from 0.008 % d-1 for Desmophyllum sp. and 0.116 % d-1 for Madrepora
oculata. Lowest calcification rates were found for corals collected at a site south off
Malta, in the Strait of Sicily, while corals collected at the canyon Lacaze Duthiers
and the Gulf of Cassidaigne in the western Mediterraanean were not significantly
different in calcification rates. Calcification rates of corals under variable pCO2 levels
were on average 0.055 % d-1 and were similar for ambient and elevated pCO2
(404-867 μatm), while calcification rates were on average 0.1 % d-1 for corals
under reduced pCO2. However, this difference was not statistically significant. Our
results indicate that cold-water corals may be able to cope, at least for a short while,
with elevated pCO2 levels and maintain a normal calcification rate. We also proved
evidence that on-board incubations are superior to study effects of climate change on
cold-water coral calcification than long-term aquarium experiments. Cold-water corals
appear to recover extremely fast from sampling stress if sampled carefully by ROV.
Conducting experiments with freshly collected cold-water corals has the advantage
that their response is close to in situ conditions and is not influenced by artificial
aquarium conditions that may not reflect the natural environment with respect to
feeding, current regimes, sedimentation and other potential factors influencing coral
behavior. A systematic comparison of calcification rates from cold-water corals
sampled over a large gradient with respect to geography, depth and seawater carbonate
chemistry is more likely to provide reliable information on the potential response of
cold-water corals to future changes in pCO2 and aragonite saturation state than
experiments conducted with corals maintained under artificial aquarium conditions. |
|
|
|
|
|
|