Resting cysts of potentially harmful dinoflagellates in Korean coastal area

Abstract

The frequency of harmful algal blooms (HABs), caused by the cyst-forming dinoflagellates, has been increasing dramatically since the 1980’s in Korean coastal waters. Although the distribution of dinoflagellate resting cysts has been widely investigated in Korean coastal areas, morphological characteristics of the resting cysts of potentially harmful dinoflagellates are still unclear. Here, we provide detailed descriptions of these potentially harmful dinoflagellates cysts to increase understanding of the morphological characteristics and biogeographic distribution of potentially harmful dinoflagellates. Sediment samples were collected from 51 stations in the southern coastal area, Korea. Viable resting cysts were isolated and induced to excysts. Identification was based on morphological characteristics and molecular phylogenetic positions of the germinated cells. Nine potentially harmful dinoflagellate species were identified: seven potentially toxic species and two potentially bloom-forming species. The resting cysts of Gymnodinium aureolum, which has a smooth, thin wall and many pale lipid globules, were first observed from natural sediments. The presence of resting cysts of potentially harmful dinoflagellates suggests that further research attention and efforts in HAB monitoring and management are required.dely investigated in Korean coastal areas, morphological characteristics of the resting cysts of potentially harmful dinoflagellates are still unclear. Here, we provide detailed descriptions of these potentially harmful dinoflagellates cysts to increase understanding of the morphological characteristics and biogeographic distribution of potentially harmful dinoflagellates. Sediment samples were collected from 51 stations in the southern coastal area, Korea. Viable resting cysts were isolated and induced to excysts. Identification was based on morphological characteristics and molecular phylogenetic positions of the germinated cells. Nine potentially harmful dinoflagellate species were identified: seven potentially toxic species and two potentially bloom-forming species. The resting cysts of Gymnodinium aureolum, which has a smooth, thin wall and many pale lipid globules, were first observed from natural sediments. The presence of resting cysts of potentially harmful dinoflagellates suggests that further research attention and efforts in HAB monitoring and management are required.