An investigation of the calcification response of the scleractinian coral Astrangia poculata to elevated pCO2 and the effects of nutrients, zooxanthellae and gender 1Dept. Marine Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
04 Jan 2012
*current address: Centre Scientifique de Monaco, Avenue Saint Martin, 98000 Monaco-Ville, Monaco
Received: 16 August 2011 – Published in Biogeosciences Discuss.: 23 August 2011 Abstract. The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate
colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786)
were investigated at two different temperatures (16 °C and 24 °C).
Corals exposed to elevated pCO2 tended to have lower relative
calcification rates, as estimated from changes in buoyant weights.
Experimental nutrient enrichments had no significant effect nor did there
appear to be any interaction between pCO2 and nutrients. Elevated
pCO2 appeared to have a similar effect on coral calcification whether
zooxanthellae were present or absent at 16 °C. However, at 24 °C,
the interpretation of the results is complicated by a significant
interaction between gender and pCO2 for spawning corals.
Revised: 10 December 2011 – Accepted: 13 December 2011 – Published: 04 January 2012
At 16 °C, gamete release was not observed, and no gender differences in
calcification rates were observed – female and male corals showed similar
reductions in calcification rates in response to elevated CO2 (15%
and 19% respectively). Corals grown at 24 °C spawned repeatedly and
male and female corals exhibited two different growth rate patterns – female
corals grown at 24 °C and exposed to CO2 had calcification rates
39% lower than females grown at ambient CO2, while males showed a
non-significant decline of 5% under elevated CO2. The increased
sensitivity of females to elevated pCO2 may reflect a greater
investment of energy in reproduction (egg production) relative to males
(sperm production). These results suggest that both gender and spawning are
important factors in determining the sensitivity of corals to ocean
acidification, and considering these factors in future research may be
critical to predicting how the population structures of marine calcifiers
will change in response to ocean acidification.
Citation: Holcomb, M., Cohen, A. L., and McCorkle, D. C.: An investigation of the calcification response of the scleractinian coral Astrangia poculata to elevated pCO2 and the effects of nutrients, zooxanthellae and gender, Biogeosciences, 9, 29-39, doi:10.5194/bg-9-29-2012, 2012.