Distribution of phytoplankton in Pangkep Waters, South Sulawesi, Indonesia

The coastal water of Pangkajene Kepulauan, or Pangkep, in South Sulawesi has been influenced by high anthropogenic activities, where the inflow of nutrient from the land has caused several cases of harmful algal blooms and mass fish mortality. Thus, it was important to understand the community structure and distribution of phytoplankton, with particular interest on the bloom-forming and harmful genus, to better mitigate the effects of harmful algal blooms in the future. Sample collection for this study was conducted on May 2017 at 22 stations from three zones, the northern, middle, and southern coastal area of Pangkep. From this study, the phytoplankton density in Pangkep was found varied between 2.179 × 106 cells/m3 to 2.192 × 108 cells/m3, with the highest density of phytoplankton was observed in the northern and southern area of Pangkep. On the other hand, the middle area has lower phytoplankton density but has the highest diversity and evenness. Two stations, station 15 and 21, have a distinct phytoplankton community structure which might have caused by a combined effect of temperature and nutrient input from the land. Twenty-nine genera of phytoplankton were observed, with the diatoms Skeletonema as the most dominant genus which contributes to over 95% of total phytoplankton density. The occurrence of Ceratium, which once was found as a dominant genus in Pangkep coastal and estuaries, has caused a concern whether it might blooms and replacing the dominance of diatoms in these areas.