ECOLOGICAL-STUDIES OF PHYTOPLANKTON IN TAI TAM BAY, HONG-KONG

Of the 141 phytoplankton species found during the sampling period, the Bacillariophyceae was the most important group and included 70% of th e total number of species; the Dinophyceae comprised a smaller percent age (28%) of the taxa; and only 3 chrysophyte species occurred through out the study period. In terms of numbers of individuals, the Bacillar iophyceae remained as the dominant group and contained 97% of the tota l numbers whereas the Dinophyceae represented only 3% of the total phy toplankton population. The most dominant diatom species was Thalassios ira allenii Takano which constituted 35% of the Bacillariophyceae grou p whereas the most abundant dinoflagellate was Prorocentrum gracile Sc hutt which represented 40% of the total Dinophyceae numbers. Chlorophy ll a levels varied from 0.40 to 32.31 mg m-3 at the surface and from 0 .33 to 33.91 Mg m-3 at the bottom. Seasonal trends of phytoplankton ab undance and chlorophyll a concentration were observed in the survey ar ea with generally high peaks in summer and low values during winter mo nths. Such variations can be attributed to the interactions between, a nd changes of, various environmental parameters, such as temperature, salinity and nutrient availability (particularly silicate).