Oxygen metabolism of a fringing reef in French polynesia

Abstract

1. Primary production was estimated during August 1975 at one station on the fringing reef of Moorea (French Polynesia) by following the diel changes of dissolved oxygen concentrations in the open water and correcting them for diffusion. Daily (24-hour) gross production amounted to 19.2 g O2 m-2 while net production showed a deficit of 3.1 g O2 m-2. Oxygen depletion occurs to a considerable extent during the night. Hourly rates provide evidence for a midday depression of photosynthesis. 2. Oxygen exchanges were also measured on benthic communities enclosed in glass jars or plastic bags. Gross production was 10.1 g O2 m-2 day-1 for an algal community dominated by Corallinaceae, 16.0 g for two non-calcareous red algae, and 3.0 g only for sands. All benthic communities produced more oxygen in a 24-hour period than they consumed. 3. The two series of observations are compared. The significance of such data with respect to "autotrophy" or "heterotrophy" is criticized. © 1976 Biologischen Anstalt Helgoland.