Factors Affecting the Germination of Akinetes of Nodularia spumigena ( Cyanobacteriaceae )

Nutritional and physical factors which influence the germination of akinetes of Nodularia spumigena (Cyanobacteriaceae) were examined. Low concentrations of phosphorus (<0.9 muM) were required for germination. Nitrate had no effect, but ammonia, at concentrations of >45 muM, inhibited germination. Salinities of >20 per thousand were inhibitory to germination. Optimum temperatures were 22 degrees C or greater. Germination did not take place in the dark, but only very low light intensities (0.5 microeinstein m s) were necessary to initiate germination. Red light (620 to 665 nm) was required. More than 24 h of continuous exposure to light was necessary for any significant germination to occur. The conditions for germination corresponded with conditions in the Peel-Harvey Estuary, Western Australia, 2 to 3 weeks before large summer Nodularia blooms.