Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

The regrowth of phytoplankton cultures after UV disinfection.

Abstract

This study addresses how cultures of three phytoplankton species - Chaetoceros calcitrans, Chlorella autotrophica and Phaeocystis globosa - can recover from the effects of UV-C exposure if the cells are placed in a rich medium. Flow cytometry and pulse amplitude modulation (PAM) were used to determine cell recovery after UV treatment. The recovery of C. calcitrans was complete 9 days after treatment. For C. autotrophica, the recovery was noticeable 5 days after treatment. P. globosa only recovered if the UV dose did not exceed 7.3×105 µWs/cm2. The recovery of the UV-treated cultures introduced to a regrowth medium, compared with the recovery of the irradiated cultures kept in their original environment, had two main characteristics: cell recovery was slower but was more efficient. This pattern of recovery has very important implications for real ballast water management systems because such systems discharge treated water into the environment.