Raphidophyte red tides in Korean waters

Abstract

Marine raphidophytes are distributed worldwide, and they often cause large-scale fish mortality in many countries. Thus, the population dynamics of raphidophytes is of critical concern to scientists, the aquaculture industry, and government officials from many countries. Raphidophytes were thought to be exclusively autotrophic organisms, but have been recently revealed as mixotrophic algae. Raphidophytes, particularly Heterosigma akashiwo, often cause red tides in Korean waters. However, raphidophytes in Korean waters have varied temporal and spatial distributions. The frequency and extent of red tides dominated by H. akashiwo in Korean waters have continuously decreased between 1998 and 2010. In contrast, between 1983 and 2005 there were only two episodes of Chattonella red tides (1983 and 1994), but Chattonella red tides have occurred every year since 2006. In the present study, we review trends in the frequency of raphidophyte red tides in Korean waters between 1983 and 2010, the nationwide distribution of raphidophytes, physical and chemical properties of the water during raphidophyte red tides, genetic variations and eco-physiology of Korean raphidophyte strains, and raphidophyte prey and predators. In addition, we provide insight as to the ecological roles of raphidophytes in Korean waters.