Effect of zooplankton availability on the rates of photosynthesis, and tissue and skeletal growth in the scleractinian coral Stylophora pistillata

Abstract

This work investigated the effect of light and feeding on tissue composition as well as on rates of photosynthesis and calcification in the zooxanthellae (zoox) scleractinian coral, Stylophora pistillata. Microcolonies were maintained at three different light levels (80, 200, 300 μmol m −2 s −1) and subjected to two feeding regimes (starved and fed) over 9 weeks. Corals were fed both natural plankton and Artemia salina nauplii four times a weeks and samplings were made after 2, 5, and 9 weeks. Results confirmed that feeding enhances coral growth rate and increases both the dark and light calcification rates. These rates were 50–75% higher in fed corals (FC; 60±20 and 200±40 nmol Ca 2+ cm −2 h −1 for dark and light calcification, respectively) compared to control corals (CC; 30±9 and 124±23 nmol Ca 2+ cm −2 h −1). The dark calcification rates, however, were four times lower than the rates of light calcification (independent of trophic status). After 5 weeks, chlorophyll a (chl- a) concentrations were four to seven times higher in fed corals (7–21 μg cm −2) than in control corals (2–5 μg cm −2). The amount of protein was also significantly higher in fed corals (2.11–2.50 mg cm −2) than in control corals (1.08–1.52 mg cm −2). Rates of photosynthesis in fed corals were 2–10 times higher (1.24±0.75 μmol O 2 h −1 cm −2) than those measured in control corals (0.20±0.08 μmol O 2 h −1 cm −2).