한국에서 유해성조류 대발생에 미치는 시스트 발아의 역할

Abstract

Harmful algal species can be present in high numbers for a short period in polar, boreal and temperate latitudes, where seasonal variations in environmental conditions are large. Nuisance algal blooms are particularly important due to their deleterious effect on fishing industries, public health and drinking water. The role of cyst germination in the bloom initiation of the harmful algal species as Alexandrium tamarense, Scrippsiella trochoidea and Anabaena flos-aquae were examined in Korean waters. To measure germination ratios of cycts and akinetes, cysts and akinetes were isolated biweekly or monthly from natural sediments samples and incubated in laboratory. The bimodal nature of Alexandrium tamarense blooms, a large bloom in spring and a much smaller bloom in fall, was observed. Germination maxima (80 to 90%) were observed during the period of decreasing water temperature in December and November, while little or no germination occurred in summer. In case of Scrippsiella trochoidea, vegetative cell numbers peaked in June to July, when the surface water temperature increased to over 18℃. Mass encystments were detected in the water column in July and August, when the vegetative population flourished. Active germination was observed during the period of decreasing water temperature in September and October, after a 2 month dormancy period following the mass encystments. The vegetative population of Anabaena flos-aquae flourished from August to November, with Anabaena verrucosa and Aphnizomenon flos-aquae observed as the dominant species. The akinetes in the sediment has a high density in the winter. The most active akinete germination occurred from the end of March to early April. A temporal discrepancy between the peak of germination success and of vegetative population was found in blooming species dynamics from Korean waters.