Algae. 2001; 16(2): 197-207.

Seasonal Dynamics of Microalgal Assemblage at Tidepools in the Southern Intertidal Zone of Cheju Island, Korea

Joon-Baek Lee, Bumn Shynn, Moo-Hyung Lee

Department of Oceanography, Cheju National University

Tidepools in the southern intertidal zone of Cheju Island were investigated to clarify seasonal variations and succession of the microalgal assemblage from March 1999 to February 2000. A total of 160 species were identified representing 117 species of Bacillariophyceae, 23 Dinophyceae, 8 Euglenophyceae, 1 Raphidophyceae, 6 Cryptophyceae, and 5 Prasinophyceae. Abundance represented 2.4×10 super(3) - 1.5×10 super(6) cells·l super(-1) with a maximum in September and a minimum in March. Phytoplankton blooms occurred from May to October. Flagellates were predominantly more abundant than diatoms at large tidepools, while diatoms dominated small tidepools. among the blooms a dinoflagellate Akashiwo sanguinea (Hirasaka) G. Hansen & Moestrup (= Gymnodinium sanguineum Hirasaka) occupied predominantly more than 50% of abundance in Bomok and Oedolgae tidepools from May to September. It also showed diurnal variations and vertical migrations at the large tidepools. Chlorophyll a concentrations ranged from 0.6 to 86.7 μg·l super(-1), which were much higher than the yearly mean in the adjacent coastal waters. Water temperature and salinity ranged from 8.7 to 32.0℃ and from 3.9 to 34.9 psu, respectively, at the tidepools showing wide ranges of variation. Total nitrogen and phosphorus concentrations also fluctuated according to season and location. In conclusion, the tidepools showed different characteristics of microalgal assemblages and wide ranges of environmental factors according to seasons and localities.

Keywords : Cheju Island, microalgae, phytoplankton, tidepool