Impact of mangroves and an agriculture-dominated hinterland on the carbon and nutrient biogeochemistry in the Segara Anakan Lagoon, Java, Indonesia.

Abstract

The Segara Anakan Lagoon on Java, Indonesia, is mainly threatened by sedimentation and mangrove tree logging. The lagoon size decreased by >50% since the 1970´s due to high sedimentation loads from the Citanduy River and therefore the agriculture-dominated hinterland. The nutrient concentrations were significantly higher during the rainy season and mainly derived from the Citanduy River. Also mangrove leaves leached high amounts of nutrients into the system. However, the nutrient concentrations were low to moderate on a global scale. Nutrient sinks in the SAL were outwelling, assimilation by mangrove and shrub species, consumption by microbes and phytoplankton. A further shift from true mangrove tree species to shrub species due to logging can alter the carbon and nutrient inventory in the lagoon. Shrub species leached significantly more nutrients than true mangrove tree species which might accelerate the nutrient turnover rates in the lagoon and therefore affect the whole food web.