THE EFFECT OF AGITATION AND TURBULENCE OF THE GROWTH MEDIUM ON THE GROWTH AND VIABILITY OF MICROCYSTIS

SUMMARY

Observation of natural blooms of Microcystis, suggested that increased turbulence plays a role in retarding bloom formation of Microcystis. In laboratory experiments the influence of turbulence mediated by a magnetic stirrer on the growth and viability of Microcystis in batch cultures was determined. The different turbulences (0, 25, 75, 126, 209 and 314 cm sec⁻¹ linear velocity) had no effect on the growth rate. There was a highly significant correlation between the linear velocity and percentage viability as determined by a plating and serial dilution method. The viability ranged from 0,8% for stationary cultures to 99,2% for vigorously stirred (314 cm sec⁻¹ linear velocity) cultures.

KEY WORDS:

• Microcystis
• agitation
• turbulence
• growth
• viability