This document specifies a bioassay for the determination of the presence of unknown toxic contaminants in test seawater (see Figure A.1). It is based on the inhibition of photosynthetic activity of the marine cyanobacterium Cyanobium sp. (NIES-981) by such toxic contaminants. The inhibition is determined based on delayed fluorescence (DF) intensity.

The method is rapid and requires less laboratory space than standard bioassays. Hence, it can be used on-board to generate basic data for seawater quality management at deep-sea mining sites where time and space are extremely limited.