Rapid monitoring for the potentially ichthyotoxic dinoflagellate Cochlodinium polykrikoides in Korean coastal waters using fluorescent probe tools

Cochlodinium polykrikoides has occurred annually in Korea’scoastal waters since 1982, where it has caused extensive fishmortality. Rapid and accurate monitoring is very important toreduce the economic damage caused by C. polykrikoides. However,before outbreaks of C. polykrikoides occur, single cells areoften more abundant than chain-forming cells. During this period,it is very difficult to discriminate C. polykrikoides from closelyrelated dinoflagellates and other phytoplankton species. Theaim of the present study was to identify even single-celledC. polykrikoides and to assess counting methodologies usingmolecular probes. A new polyclonal antibody bound specificallyto C. polykrikoides, and not to other phytoplankton, includingthe morphologically similar Gyrodinium impudicum and Gymnodiniumcatenatum. When cultured C. polykrikoides cells were fixed with2.5% glutaraldehyde, they emitted a high-intensity fluorescentsignal during the period of exponential growth. The correlationwith cell density of a mixed culture including C. polykrikoidestreated with an antibody and lectin probes (wheat germ agglutinin/Erythrinacristagalli agglutinin) was well matched (r² = 0.83). The detectionof C. polykrikoides was possible at concentrations as low as5 cells ml^-1. Reaction with C. polykrikoides antisera and antigenby western blotting analysis was at 30 kDa and gave no signalfor G. impudicum, G. catenatum, Alexandrium tamarense or Prorocentrummicans. Consequently, the new antibody is of great importancefor enumeration and identification of C. polykrikoides in Korea’swaters.