Ecological behavior of the dinoflagellate Ceratium furca in Jinhae Bay, Korea

Abstract

To better understand the mechanism underlying the bloom outbreaks of dinoflagellate Ceratium furca in the temperate coastal area of Jinhae Bay, we investigated the diel changes of vertical migration (DVM) and cell division timing. Field sampling were carried out at a fixed station at three-hour intervals between 29 July 2009 to 1 August 2009 from 0, 2, 4, 6, 8 m depths, when the C. furca bloom continuously persisted. In addition, to better understand the DVM related to cell division, we collected 12 hourly samples from 03:00 to 06:00 AM. The maximum cell densities of C. furca was 10,640 cells mL-1and observed at 24:00 on the surface on 1 August, while relatively high concentrations were routinely recorded at 6:00 on the surface. The high proportions of dividing cells had a positive correlation with depth and a weighted mean depth (WMDs) was also deeper. Consequently, C. furca divide in the deeper layer, irrespective of vertical migration pattern. C. furca has an ecological advantage over other algal species under unfavorable environmental conditions such as low nutrient availability and swimming capacity to avoid high-light-induced cell damage. Such ecological abilities can play an effective role for adaptation to local environmental conditions. Also, the dividing cells observed in the deeper layer may be as a result of ecological adaptations for efficient reproduction, because passing