Seasonal variation in photosynthesis, dark respiration and growth rate of two reef building corals in the red sea coast

Abstract EN

The seasonal variation in photosynthesis, dark respiration and growth rate of two reef building corals, Seriatopora hystrix and Lobophyllia corymbosa inhabiting the coast of Red Sea was studied during summer and winter.

Results showed that there is a little variations in the respiration rates of the zooxanthellae between the two species and season (Summer and Winter).

The respiration rates decreases gradually according to the season variations .

Photosynthesis versus irradiance (P v I) curves was obtained and lines fitted to the data using the hyperbolic tangent function.

The lower Pgmax values were observed in Seriatopora hystrix in winter than in summer, hence sensitive to the temperature variations.

Conversely, the Pgmax of Lobophyllia corymbosa was higher in summer than in winter, suggesting the possibility of compensatory process of either the lower light-levels or lower water temperature during winter.

The growth rate of the two species was lower in the winter than in summer.

The light quality and intensity and seawater temperature during summer also affected the growth rate of the two species.