Effects of environmental factors on the uptake rates of dissolved nitrogen by a salt-water green alga (Oocystis borgei Snow).

Uptake rates for dissolved nitrogen (DN) by a marine alga (Oocystis borgei) were examined in a (15)N tracer experiment. Maximal uptake rates for all forms of DN were observed at temperatures between 25 and 30°C and at algal concentrations between 3.22 × 10(8) and 4.78 × 10(8 )cell L(-1). Light intensity required to achieve the maximal uptake rate was 45 μmol m(-2) s(-1) for dissolved inorganic nitrogen (DIN = NO(3) (-), NO(2) (-), NH(4) (+)) and methionine, and 126 μmol m(-2) s(-1) for urea. Salinity required to achieve the maximal uptake rate was 12.85 ppt for DIN, 19.89 ppt for urea and 26.2 ppt for methionine.