Seasonal Mechanisms of Nutrient Input and Its Potential Impacts on Productivity and Pollution in Arafura Sea: a Review

Two different mechanisms of nutrient inputs seasonally in Arafura Sea were reviewed in order to understand the outcomes of these mechanisms on the primary production in supporting fishery industries and marine pollution. The mechanism of nutrient inputs in Arafura Sea during the southeast monsoonal winds were based on undercurrent circulation newly reported by Kämpf’s very recent studies. We pointed out that the modelling findings of the studies demanded a further validation of the bulk of nutrient in Arafura Sea observationally (i.e., direct measurements) particularly at the northwestern Arafura Sea where the undercurrent circulation was evident. Additionally, it was important to measure the degree of the vertical nutrient flux as a result of the Ekman pumping in the eastern Banda Sea which was not considered by the recent studies to understand how much the upwelled water induced by Ekman pumping in the eastern Banda transported to Arafura Sea basin via the undercurrent mechanism. For the nutrient input mechanism in Arafura Sea during the northwest monsoon season, we calculated the rate of the exchange process between the southwest Papua coastal waters and Arafura Sea (26 km3/day) leading to the extent of the freshwater river plume of 73 km to the Arafura Sea. This freshwater plume extent was comparable with the width of the Chl-a concentration towards the SW Papua coastal waters (~ 45 km) indicating the dependence of phytoplankton communities at the coastal waters on the seaward freshwater flow. In addition, it was thought to be possible that the exchange process between the SW Papua coastal waters and Arafura Sea potentially brought negative buoyant plume-like sediment at the subsurface water column of the coastal waters beside the surface freshwater plume. Pertemuan Ilmiah Nasional Tahunan XIII ISOI 2016. Hal. 507-517