Coral nutrition: Comparison of the fate of 14C from ingested labeled brine shrimp and from the uptake of NaH 14CO 3 by its zooxanthellae

Abstract

Previous work has shown that the biochemical composition of the tissues of the scleractinian coral Astrangia danae Milne Edwards & Haime 1849 depends both on the nutritional history of the animal and on the presence or absence of symbiotic algae. To compare further the nutritional effects of feeding frequency and the contribution by algal symbionts, colonies of Astrangia were fed 14C-labeled Artemia or were incubated with NaH 14CO 3. The fate of the labeled carbon was determined in each case by fractionating the tissue into its major biochemical components. The proportion of food-derived 14C appearing as coral lipid was slightly greater in corals fed more frequently, and also in those with zooxanthellae. Symbiotic corals retained 10% more of the labeled brine shrimp carbon than did the non-symbiotic ones. Zooxanthellae of corals fed 1/wk fixed more 14C but translocated less of it than did the algae of starved corals. Most of the 14C translocated from the algae ended up as coral lipid and nucleic acid, while the brine shrimp 14C was converted mostly to lipid and protein. These results suggest that in well-fed corals less carbon from ingested food or zooxanthellae-translocate is used for immediate metabolism and more is stored in the lipid fraction of the coral.