Nutrient and chlorophyll-a distribution in Makassar Upwelling Region: From MAJAFLOX CRUISE 2015

Abstract

Upwelling is an important mechanism on productivity enhancement in the Southern Makassar Strait (MAK). Previous studies found correlation between upwelling and chlorophyll-a blooms, which is perhaps caused by nutrient regeneration from deeper water. Through a multi-disciplinary study "MAJAFLOX Cruise" in August 2015, CTD casts and seawater samples have been collected from Southern Makassar Strait. The present study aims to investigate relationship between physical processes of upwelling and nutrient usage, especially for nitrate, phosphate and silicate from regenerated processes to be used for the primary productivity (chlorophyll-a). The results show that upwelling centre is found near Dewakang Sill around station 5, associated with the highest chlorophyll-a concentration (0.438 µgL-1). Relatively high nutrient is also revealed in other station of observation. In sea surface layer, nitrate is high in station 1 to 3, phosphate high in station 2 and silicate high in station 9. This shifting of high nutrient concentration may indicate spatial variation of biogeochemical processes in the surface layer associated with nutrient fluxes.