THE AVAILABILITY OF DISSOLVED ORGANIC PHOSPHORUS COMPOUNDS TO MARINE PHYTOPLANKTON

The availability of three dissolved organic phosphorus （DOP） compounds as nutrient sources for experimentalcultare of three algae was studied. Results indicated that these compounds could be utilized byalgae, and that dissolved inorganic phosphorus （DIP） was first to be uptaken when various forms ofphosphorus （DIP and DOP） co-existed. Dicrateria zhanjiangensis’ uptake of sodium glycerophosphatewas faster than that of D-ribose-5-phosphate. The increase of sodium glycerphosphate had little effecton the maximum uptake rate(V) of Chlorella sp., but increased the semisaturation constant（K） remarkably;the photosynthesis rates（PR） of Dicrateria zhanjiangensis and Chlorella sp. were rarely affected byusing various forms of phosphorus in the culture experiments. The possible DOP pathways utilizedby algae are discussed.