The eutrophication states of the Indonesian sea large marine ecosystem: Jakarta Bay, 2001–2013

Abstract

Eutrophication states of the tropical embayment of Jakarta Bay, Indonesia were studied over the period of 2001–2013. There was a clear gradient of dissolved inorganic nutrient concentration, showing very high values in the river mouths and a steep decrease down the Bay. This is followed by a steep gradient of Chl-a concentration, showing high phytoplankton biomass in the river mouth areas (31.4 μg Chl-a l−1) and a 2-fold decrease in the inner part of the Bay (15.8 μg Chl-a l−1), a 4-fold decrease in the middle part of the Bay (7.8 μg Chl-a l−1) and a 14-fold decline in the outer part of the Bay (2.2 μg Chl-a l−1). On a seasonal basis, phytoplankton biomass is higher during the dry period compared to that of the rainy period, due to a better combination of nutrient and light availabilities. There was no significant change in eutrophication level during the last 12-year period (between 2001 and 2013), showing relatively stable nutrient pollution levels in Jakarta Bay. Undesired eutrophication symptoms of hypoxia and algae blooms have been frequently detected in Jakarta Bay, which can be a serious threat to fish consumption safety of humans.