Meteorological conditions preceding Chattonella bloom events in the Yatsushiro Sea, Japan, and possible links with the East Asian monsoon

Abstract

The relationship between harmful blooms of raphidophycean flagellate Chattonella spp. and preceding meteorological conditions was investigated in the Yatsushiro Sea, Japan, using data over a 25-year period from 1988 to 2012. The occurrence date of Chattonella blooms was significantly correlated with the average air temperature from February through April and with the onset date of Baiu, the Japanese name for the rainy season in early summer. These two meteorological factors showed significant differences between occurrence and non-occurrence years of Chattonella blooms in the Yatsushiro Sea. The Chattonella blooms tended to occur in years that were relatively warm from winter to spring and had a relatively late onset of Baiu. The duration of Chattonella blooms was significantly correlated with the interval between the closing date of Baiu and the occurrence date of the Chattonella blooms, suggesting an important role of Baiu as nutrient input affecting the magnitude of the bloom event. The East Asian monsoon, which controls local meteorological conditions, is likely involved in the population dynamics of Chattonella through its life cycle and physiological characteristics.