CHEMICAL-COMPOSITION AND ALKALINE-PHOSPHATASE ACTIVITY OF NUTRIENT-SATURATED AND P-DEFICIENT CELLS OF 4 MARINE DINOFLAGELLATES

Four marine dinoflagellates, Amphidinium carterae Hulburt, Ceratium tripos (O.F. Mull.) Nitzsch, Prorocentrum minimum (Pav.) J. Schiller and Scrippsiella trochoidea (Stein) Loeblich III were grown as dilution cultures at 18.degree. C, S [salinity] = 29.permill. and 30 .mu.E .cntdot. m-2 .cntdot. s-1 [E = einstein] at L:D = 14:10 h. In nutrient-saturated cultures, the growth rates (double [doublings] .cntdot. day-1) ranged from 0.38 for Scrippsiella to 0.80 for Prorocentrum, and C content (pg .cntdot. cell-1) from 83 for Amphidinium to 6900 for Ceratium. The atomic N/C ratio ranged from 12-13 for Ceratium and Scrippsiella to 15-17 for Prorocentrum and Amphidinium. Under P-deficient conditions (growth rate 39-70% of the maximum), cellular P decreased considerably, but so did N, so that the N/P ratio was only slightly affected. There was a concomitant increase in C content per cell of 1.2- to 1.7-fold. Alkaline phosphatase activity was virtually nil in nutrient-saturated cells, but was readily demonstrable in all species when P-deficient.