An Overview on the Occurrences of Harmful Algal Blooms (HABs) and Mitigation Strategies in Korean Coastal Waters

Recent wide spread and persistent harmful algal blooms (HABs) give severe impacts on public health and fisheries economics along all coasts of Korea. As the HABs have become more widespread and caused increasing fisheries damage, Korea established an integrated monitoring system included oceanographic, environmental, and red tides observations. Both oceanographic and environmental data and remotely sensed information are available for HABs prediction. Hierarchical HABs monitoring whose observation time is based on the frequency of HABs occurrence for the last five years has been run to take appropriate response actions according to the HABs magnitude since 1996. Korea has been employed a variety of mitigation strategies directly or indirectly to affect the size of a HAB population or its impacts. They can be classified into two categories: precautionary impact preventions, and bloom controls. To give precautionary attention to fishermen and aquaculturists, Korea has been operating an alert system. It consists of several alerts such as ‘Red Tide Attention’, ‘Red Tide Alert’ and ‘Warning Lift’. As one of direct HABs controls, Korea has dispersed yellow clay on coastal aquaculture farms to remove fish killing C. polykrikoides blooms since 1996. The clay can flocculate the dinoflagellate cells and causes them to sink to the bottom of the water body. This can dilute the cell density of dinoflagellates in the cages thereby not killing the accommodating fish. It has so far proven not to induce significant negative impacts on water quality or benthic organisms. In addition to clay dispersal, Korea is studying other possible mitigative substances and techniques such as biological and physical controls. Korea has joined the regional and international meeting, and continues to exchange data and information with neighboring countries such as Japan, China, South East Asian countries, and Russia through NOWPAP, PICES, APEC, and EASTHAB meetings.