HOST FEEDING REGIME AND ZOOXANTHELLAL PHOTOSYNTHESIS IN THE ANEMONE, AIPTASIA PALLIDA (VERRILL).

Oxygen production was measured in the anemone Aiptasia pallida (Verrill) maintained at varying feeding regimes in the laboratory. Host feeding regime had no significant effect on: (1) zooxanthellal gross photosynthesis (GPPmax) expressed as µg O2 · µg chl a-1 · h-1 or µg O2 · 106 zooxanthellae-1 · h-1; (2) the light intensity at which ½ GPPmax occurs (Km); or (3) the chlorophyll a content of the zooxanthellae. Starvation significantly reduced GPPmax expressed as µg O2 · mg host protein-1 · h-1 and zooxanthellal density within the host. Zooxanthellal translocation efficiency was measured by short term incubations of anemones in NaH14CO3. Host feeding regime had no effect on the percentage of 14C translocated to the host. These results suggest that, under these conditions, starvation did not alter the photosynthetic capability of the zooxanthellae but decreased total photosynthate translocated to the host by decreasing zooxanthellal density within the host.