Phytoplankton Enumeration and Evaluation Experiments

Abstract : A workshop was held 6-16 January 2008 to evaluate the ability of various analysis methods to detect, enumerate, and determine the viability of phytoplankton at concentrations to be expected after treatment by successful ballast water treatment systems. Researchers from Woods Hole Oceanographic Institute, Moss Landing Marine Laboratory, Naval Research Laboratory, and Fluid Imaging Technologies were provided with six samples with known concentrations of live and dead Tetraselmis species in prepared seawater. A seventh sample contained live Tetraselmis plus dissolved organic matter and mineral matter to better mimic actual ballast water samples. Methods investigated included manual microscopy with vital stains, microscopy of concentrated samples stained with different stains, flow cytometry of stained organisms, pulsed amplitude modulated (PAM) fluorometry, and an enhanced flow-through system with imaging capability. Statistical analyses were performed on the results. Overall the methods were all self-consistent. Although there were differences from sample to sample, comparisons showed no real differences could be established indicating one method is better than others. Advantages and disadvantages of each analytical method for routine use are provided.