Dynamics and size structure of phytoplankton in the coastal waters of Singapore

In this paper, a study on phytoplankton dynamics and size in the tropical coastal waters of Singapore is presented. Chlorophyll-a levels in the Singapore Strait generally range from 0.4 to 10 mu g l(-1), with an average value of 1.7 mu g l(-1). In general, higher chlorophyll concentrations are typically found off the cast coast of Singapore, as well as in the shallower, more protected waters of the Johor Strait (maximum similar to 78 mu g l(-1), average = 21.5 mu g l(-1)). Seasonal trends in chlorophyll and nutrients are also apparent, with higher chlorophyll generally observed during the south-west monsoon compared with the wetter north-east monsoon. Size-fractionated chlorophyll measurements of the phytoplankton community show that fur low standing stocks of chlorophyll less than 3 mu g l(-1), approximately 40% of the phytoplankton lies in the pico- and small nanoplankton (<8 mu m) size range. As total chlorophyll levels in the system increase, the relative contribution from the larger size classes (i.e. 8-20 and 20 -100 mu m) increases, with a subsequent decrease in the smaller size classes. For total chlorophyll greater than 40 mu g l(-1), it was found that the 20-100 mu m size class contributed 60% of total chlorophyll. In contrast, the <8 mu m size class contributed only about 5% of total chlorophyll fur these waters.