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.

Supplement to: Drits, Alexander V; Semenova, Tatyana N; Konovalov, Boris V (1987): Production of Zooxanthellae in planktic foraminifera and colonial radiolaria of the tropical Atlantic Ocean. Oceanology, 27(1), 92-97