Journal Article

Effects of light and elevated pCO sub(2) on the growth and photochemical efficiency of Acropora cervicornis

Enochs, I C, Manzello, D P, Lirman, D, Schopmeyer, S, Carlton, R, Hooidonk, R

2014

Overview

The effects of light and elevated pCO sub(2) on the growth and photochemical efficiency of the critically endangered staghorn coral, Acropora cervicornis, were examined experimentally. Corals were subjected to high and low treatments of CO sub(2) and light in a fully crossed design and monitored using 3D scanning and buoyant weight methodologies. Calcification rates, linear extension, as well as colony surface area and volume of A. cervicornis were highly dependent on light intensity. At pCO sub(2) levels projected to occur by the end of the century from ocean acidification (OA), A. cervicornis exhibited depressed calcification, but no change in linear extension. Photochemical efficiency (F sub(v)/F sub(m)) was higher at low light, but unaffected by CO sub(2). Amelioration of OA-depressed calcification under high-light treatments was not observed, and we suggest that the high-light intensity necessary to reach saturation of photosynthesis and calcification in A. cervicornis may limit the effectiveness of this potentially protective mechanism in this species. High CO sub(2) causes depressed skeletal density, but not linear extension, illustrating that the measurement of extension by itself is inadequate to detect CO sub(2) impacts. The skeletal integrity of A. cervicornis will be impaired by OA, which may further reduce the resilience of the already diminished populations of this endangered species.

• Subject: Acropora cervicornis