A technical method for assessing the viability of phytoplankton to examine the performance of a ballast water management system

Abstract

In the case of examining the performance of ballast water treatment systems, it is necessary to follow the "Guidelines for approval of ballast water management systems (G8)" by the IMO-MEPC. When determining the performance of a ballast water treatment system using plankton viability, the plankton cells should be counted within 6 hours after the treatment to verify if the number of viable plankton is reduced below the ballast water management standard, or the sample should be treated in such a way so as to ensure that a proper analysis can be performed. In order to count the number of viable phytoplankton more efficiently, a suitable method of staining plankton cells with neutral red (NR) is described in the present paper.

The phytoplankton that can be stained with the NR method include Bacillariophyceae, Chrysophyceae, Dinophyceae, Cryptophyceae, Raphidophyceae, Haptophyceae, Euglenophyceae and autotrophic micro-flagellates. This NR method can also be applied to general phytoplankton in other taxa and to various sizes of cells that appear in coastal areas. However, the pH value of the ballast water during the treatment must be above 7.0 and below 8.5, otherwise it may have an effect on the staining performance; therefore, a positive check is needed before the method is applied.