Experiments were designed to assess the uptake rates of 0.2, 1, and 5 μM ammonium by the scleractinian coral Stylophora pistillata maintained under different feeding regimes (highly fed, slightly fed, and starved) for 4–8 weeks. 15 NH 4 was used to follow the incorporation of nitrogen in the zooxanthellae or in the animal tissue and to calculate uptake rates. After 4 or 8 weeks, fed corals contained significantly higher concen...