Quantifying indicatively living phytoplankton cells in ballast water samples — recommendations for Port State Control

Different phytoplankton analysis methods (pulse-amplitude modulated fluorometry (PAM) and microscopy) were compared in preparation for compliance monitoring and enforcement with ballast water discharge standards. The key objective was to practically evaluate the performance of different new methods and tools to identify indicatively living phytoplankton cells of the size < 50 μm in minimum dimension and ≥ 10 μm in minimum dimension as addressed by the Ballast Water Performance Standard (Regulation D-2, International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004). Four different PAM instruments were selected for the tests based upon knowledge and experience gained in different ballast water sample processing studies. The measurements of the PAM instruments were compared with epifluorescence microscope algae cell counts using fluorescein diacetate as viability stain. It was concluded that PAM fluorometry is a suitable method for indicative phytoplankton analysis of ballast water and the most accurate PAM instruments were identified.