Investigation of encystment in Karenia sp.(Dinoflagellate) in vitro

Dinoflagellates play a very important role in the formation of harmful algae bloom, and many of them, during their life cycle, can reduce their physiological activities and enter into an encystment phase, settling in sediment, forming a resting cyst. Benthic cyst stages are very important in the life cycle of dinoflagellate, and the cyst bloom in the water column can initiate a harmful algal bloom. Dinoflagellate species belonging to the genus of Karenia are in the ocean and coastal waters and have the potential to cause harmful algae (HABs) in summer or autumn. Bloom of some species in Karenia genus can cause severe environmental and economic consequences by producing various types of toxins. This genus includes 12 species and some of its species form a cyst during their sexual life-cycle and settle in the sediment. Karenia brevis is a holotype species that, by form, HABs creating respiratory, skin disease and neuronal intoxication in humans. The cyst could have an important role in the Plankton bloom. In order to study the life cycle of Karenia sp. species isolated from the Red-tide, in November 2017, a water sample was collected with a one-liter bottle from the Lipar zone located on the south-east coast of Iran after the summer monsoon. The purification stages of the species were performed in vitro and the obtained strain was examined. The pure isolate was cultured in a fully sterile medium under 12-L: 12-D hour at 25 ℃ in f2 culture media. Based on the morphological characteristics of this species, the Karenia sp. was identified belonging to the Miozoa division. The cells in an appropriate culture medium, in vitro conditions were incubated for cyst formation and the Petri dishes weekly were examined for six months and the results showed that encystment did not occur in the plankton cells, which caused planktonic bloom in southern waters of Iran, there was no cyst produced during life cycle of this species. This study showed that the Karenia sp. species of Lipar in 2017 that produced a planktonic bloom, did not have the ability to produce resting cysts under laboratory conditions. In order to accurately identify the harmful planktonic species of the Red-tide, the study of the potential of cyst production and life cycle of these cells is necessary and essential and has a special importance in environmental studies

Keywords:

Cyst , Dinoflagellate , Karenia sp. , Summer monsoon , HABs