MEPS 177:299-304 (1999)  -  doi:10.3354/meps177299

ABSTRACT: A new experimental and analytical protocol enabling the measurement of the metabolism of aquatic communities in open-top mesocosms is described. It involves estimation of air-water gas exchange and use of a polynomial regression to estimate metabolic parameters from measurements of dissolved oxygen concentration. Sample data is provided for a coral reef community. Its major advantage compared to the standard respirometry technique is that the community is not subject to great variations of physical and chemical parameters such as dissolved oxygen concentration or pH during the experiment. Changes in the concentration of dissolved oxygen were measured over 24 h periods and used to derive community gross photosynthesis (P_g) and respiration (R). Experiments performed on the same community with 2 differents light intensities (360 and 250 µmol m^-2 s^-1) provided consistent estimates of P_g (208 ± 50 and 73 ± 20 mmol O₂ m^-2 d^-1) and R (-219 ± 55 and -79 ± 29 mmol O₂ m^-2 d^-1). The air-water oxygen transfer velocities, K_O2, varied between 34 ± 5 and 84 ± 12 cm h^-1. This approach provided estimates of community metabolism that are not significantly different from those obtained using the standard respirometry technique.

KEY WORDS: Primary production · Respiration · Mesocosms · Coral reef community · Aquatic ecosystem