The short-term partitioning of carbon-14 assimilate between zooxanthellae and polyp tissue in Acropora formosa

The usefulness of Fluorinert for the extraction of Acropora formosa polyp tissue and zooxanthellae was demonstrated. The latter remain intact, with no leakage of metabolites, and the polyp tissue can be extracted in a minimal volume. Intact A. formosa and its isolated zooxanthellae were incubated in the light with sodium ¹⁴C]bicarbonate for 5 s to 15 min and the kinetics of carbon-14 fixation was determined. The isolated zooxanthellae showed a linear response for carbon fixation, whilst the zooxanthellae in the intact association showed a lag period of 1 to 2 min, containing only 12% of the total fixed carbon in the first 1 min. After 10 min, the distribution of fixed carbon between the symbiotic partners was approximately even and the total carbon fixed was in a range similar to that fixed by the isolated zooxanthellae. A pulse-chase experiment showed rapid movement of fixed carbon from the polyp tissue to the zooxanthellae after the 30 s pulse. The paper discusses two possible explanations for the observed results.