Production of Zooxanthellae in the tropical Atlantic Ocean

The radiocarbon method was used to measure primary production of Zooxanthellae of five colonial radiolaria and two pelagic foraminifera from the tropical Atlantic Ocean; in addition, chlorophyll-a concentrations were determined, and assimilation numbers were calculated. It was estimated empirically that about 40% of 14C participating in photosynthesis later passes from symbiotic algae to radiolarian endocytoplasm; this makes it possible for them to survive extended starvation conditions. Contribution of Zooxanthellae to overall primary production of the studied oligotrophic region is small; biomass of symbiont-containing plankton organisms did not exceed 1% (in carbon units) of total seston mass.