Monitoring and trends in harmful algal blooms and red tides in Korean coastal waters, with emphasis on Cochlodinium polykrikoides

Abstract

Red tides have a long history in Korea with the first record in AD 161, and a total of 38 red tide events reported from AD 161 to 1820. Since the 1980s, the frequency of red tide events has increased and the red tide area has expanded. From 1972 to 2001, 1330 red tide events occurred, and 273 (20.5%) were caused by fish killing dinoflagellates, mostly since the mid 1990s. Overall, the diatom Skeletonema costatum and the dinoflagellate Karenia mikimotoi were dominant HAB species in the 1970s and 1980s. However, the dominant red tide species changed to the dinoflagellates Cochlodinium polykrikoides and Ceratium spp. and the raphidophytes Chattonella spp. in the 1990s and 2000s. In addition, the dinoflagellate Akashiwo sanguinea and Heterosigma akashiwo have been major components during red tides the past four decades. After 1995, when a massive C. polykrikoides bloom occurred, the National Fisheries Research and Development Institute (NFRDI) and local governments began monitoring red tides nationwide. Along with the NFRDI, more than 30 fisheries extension service stations under local governments monitor red tides. The National Maritime Police Agency monitors the movement of red tides using aerial surveillance with helicopters. Paralytic shellfish poisoning events are also monitored by the red tide monitoring network system of NFRDI and local governments. We reviewed here historical records of red tides in Korea, red tide monitoring systems, trends in frequency of occurrence of red tide events, and red tide causative species in Korean waters. Red tide dynamics and physical–environmental factors potentially related to C. polykrikoides red tides are also discussed; red tides caused by C. polykrikoides along Korean coasts have decreased sharply starting from 2008 after achieving a high density bloom annually from 1995 to 2007.