Metabolic balance of the polyp-algae mutualistic symbiosis in the hermatypic coral Porites panamensis in La Paz, Baja California Sur, Mexico.

Abstract

Studies on metabolic balance in hermatypic corals have been unable to separate the analysis ofanimal’s respiration from that of plant. The objective of this research was to determine the metabolic balance in the mutualistic symbiosis polyp-algae through incubations in respirometric chambers of twelve fragments of coral. The species studied Porites panamensis (Scleractinia: Poritidae), Verrill, 1866 was collected near La Paz, Baja California Sur, México. Experiments were  performed during fall 2009 and winter 2010. Water temperature, salinity, dissolved oxygen, pH, irradiance and photosynthetic pigments were measured every two hours during the incubation times. The concentration of pigments was  determined through spectrophotometry. The maximum primary production was at 12:00 h, with 3.80 mg O2∙l-1∙h-1 for fall and 4.92 mg O2∙l-1∙h-1 for  winter. According to the P : R (Production :  Respiration) ratio of 1.90 for fall and 2.07 for winter, the mutualistic symbiosis in P. panamensis showed a predominantly autotrophic behavior. The relative quotients of chlorophyll concentrations (mg∙polyp-1), Chl a : Chl c2, were 1.0 : 0.69 for fall and 1.0 : 1.22 for winter; while ratio of concentrations chlorophyll a : carotenes , Chl a : carotenes (both in mg∙polyp-1), were 1.0 : 2.13 for fall and 1.0 : 1.88 for winter. The high relative concentrations of Chl c2 and carotenes with respect to Chl a is explained as an adaptive response to high irradiance.