ON THE FEEDING OF SOME SCLERACTINIAN CORALS WITH BACTERIA AND DISSOLVED ORGANIC MATTER

Feeding experiments were carried out with 6 species of common scleractinian reef‐building corals from reefs of the Bismarck Archipelago. Their ability to utilize planktonic bacteria and dissolved organic matter (protein hydrolyzate) as food was demonstrated by using radiocarbon. The amount of organic carbon assimilated per day by animals given labeled food at concentrations approaching those found in situ was equivalent to 10–20% of the carbon content of the polyp’s body. The rate of consumption and assimilation of some planktonic algae by corals was much lower. Corals could consume organic phosphorus bound in the cells of planktonic bacteria more actively than inorganic phosphate at the same concentration (several µ g liter 1 ). The rate of consumption of phosphorus was 3 µ g g −1 day −1.