Metabolic costs of larval settlement and metamorphosis in the coral Seriatopora caliendrum under ambient and elevated pCO2

We tested the effects of pCO2 on Seriatopora caliendrum recruits over the first 5.3 d of post-settlement existence. In March 2011, 11–20 larvae were settled in glass vials (3.2 mL) and incubated at 24.0 °C and ~ 250 μmol quanta m− 2 s− 1 while supplied with seawater (at 1.4 mL s− 1) equilibrated with 51.6 Pa pCO2 (ambient) or 86.4 Pa pCO2. At 51.6 Pa pCO2, mean respiration 7 h post-settlement was 0.056 ± 0.007 nmol O2 recruit− 1 min− 1, but rose quickly to 0.095 ± 0.007 nmol O2 recruit− 1 min− 1 at 3.3 d post-settlement, and thereafter declined to 0.075 ± 0.002 nmol O2 recruit− 1 min− 1 at 5.3 d post-settlement (all ± SE). Elevated pCO2 depressed respiration of recruits by 19% after 3.3 d and 12% overall (i.e., integrated over 5.3 d), and while it had no effect on corallite area, elevated pCO2 was associated with weaker adhesion to the glass settlement surface and lower protein biomass. The unique costs of settlement and metamorphosis for S. caliendrum over 5.3 d are estimated to be 257 mJ recruit− 1 at 51.6 Pa pCO2, which is less than the energy content of the larvae and recruits.

► We developed techniques to grow coral recruits over the first days of life. ► Settlement of coral larvae causes respiration to increase 70% within 4 d. ► Elevated pCO2 reduced the metabolic rates of coral recruits. ► The costs of settlement and metamorphosis are 257 mJ recruit− 1 over ~ 6 d. ► Coral larvae & spat contain enough energy to meet the costs of settlement over ~ 6 d.