Harmful Effect of Dinoflagellate Heterocapsa circularisquama on Shellfish Aquaculture in Japan
The marine dinoflagellate Heterocapsa circularisquama Horiguchi is the causal agent of red tide on the Japanese coast. In the last decade, H. circularisquama red tides have destroyed the shellfish aquaculture industries around the western part of Japan because this dinoflagellate shows a detrimental effect on shellfishes particularly on bivalve molluscs. The current proliferation of H. circularisquama throughout western Japan is a cause for concern due to economic loss. The outbreaks of H. circularisquama are closely related to the environmental conditions: water exchange rate, water temperature, local and global climate changes. Administrative measures such as algal monitoring systems can be successfully utilized for the distribution and short-term prediction of red tide due to H. circularisquama in several locations. However, secondary damage, i.e. decline of demand due to misinformation and cost of measures to prevent the damage, adversely affects the development of shellfish aquaculture even if direct killing of the products can be avoided.