Macronutrient interactions involved in cyanobacterial bloom formation

Summary

Cyclostat and lake mesocosm experiments have indicated that the relative gas vacuolation (cyclostat cultures) and buoyancy (lake populations) of cyanobacteria can very inversely with the availability of inorganic carbon (C_i). Here, we report the results of experiments, involving various C, N and P treatments, on natural populations of Oscillatoria and Anabaena. These results suggest that the buoyancy responses of cyanobacteria to changes in C_i) availability depend on the availability of N and P. For example, additions of C_i) alone to surface populations of Anabaena and Oscillatoria hastened the decline of such populations. Whereas, C_i) enrichment of N- and P-enriched, deepwater populations of Oscillatoria stimulated bloom formation.