Coastal Upwelling And Phytoplankton Biomass In Terengganu And Pahang Coastal Waters

Abstract

Oceanographic cruises were conducted to investigate the dynamical relationship between hydrography, current circulation and phytoplankton biomass at the east coast of Peninsular Malaysia (ECPM) and elucidate the structure of upwelling at the ECPM especially in the vicinity of Tioman Island. Physical observations in the upwelling area were analysed with respect to local wind forcing. Chlorophyll a and nutrients measurements were discussed based on different seasonal influence. In addition to field data measurement, satellite images were used to demonstrate the presence of upwelling and examine the spatial patterns of phytoplankton biomass at the ECPM. The outcome of this study showed that the southwesterly monsoon wind, which induced coastal upwelling, was the major mechanism that shaped the hydrographic character and the relatively high phytoplankton biomass found at the study area. Results also showed that the waters off Tioman Island had relatively cooler temperature and higher phytoplankton biomass due to nutrient enhancement than Terengganu. The presence of this character was in response to strong northward upwelling and freshwater intrusion in both areas. In the vicinity of Tioman Island, there was a small but distinguishable cooler-upwelled water and slightly stronger current at the north of the island. This feature appeared to be caused by the interaction of multiple dynamical processes including coastal upwelling, island circulation and topographic variations in this area. Overall, the interaction of physical processes between wind-induced upwelling, coastal current and island circulation were believed to be the key drivers in regulating the hydrography and horizontal as well as vertical distribution of phytoplankton biomass.