Quantifying potential benefits to Microcystic aeruginosa through disentrainment by buoyancy within an embayment of a freshwater river

Vertical profiles of Microcystis aeruginosa and other phytoplankton were me asured on several occasions within the main channel and an embayment of a f reshwater tidal river. The cyanobacteria M. aeruginosa and Anabaena circina lis were able to migrate to surface waters within the embayment but not wit hin the main channel. Using a quantitative estimate of primary productivity (over a 24 hour period), the potential benefits through disentrainment by buoyancy were determined for M. aeruginosa within the embayment and compare d to the main channel. The population within the embayment had a daily inte gral of photosynthesis of 603.13 mmol of O(2)m(-2), nine times greater than the evenly distributed main channel population with a daily integral of 62 .08 mmol of O(2)m(-2). It is likely that embayments along the tidally mixed reaches of the Hawkesbury River may be areas where M. aeruginosa can disen train through buoyancy and enhance primary productivity rates.