|Beschreibung:||Six seasonal measuring campaigns were performed in the period December 2000 to December 2001 in order to investigate the effects of anthropogenic nutrient enrichment on the seasonal dynamics of phytoplankton biomass and production in 3 Indonesian embayments subjected to a different degree of anthropogenic pressure. Jakarta Bay receives the highest riverine nutrient load (21260 t DIN/y), when compared to those of Lampung (5003 t DIN/y) and Semangka Bay (1378 t DIN/y). These high loads resulted in high concentrations of dissolved nitrogen, phosphate and silicate in the bay, with annual averages of 20 µM N, 5 µM P and 45 µM Si. In keeping with this, mean levels of chl-a and annual primary production were considerably higher than in the two other bays under investigation, accounting for 13 µg/l and 223 g C m^2 y^-1, respectively. Lampung Bay exhibited mean chl-a levels of 4 µg/l and an annual primary production of 89 g C m^2 y-1, whereas in the less nutrified Semangka Bay they were only 0.8 µg/l and 25 g C m^2 y^-1. The phytoplankton community was dominated by diatoms in all of the bays. The occurrence of dinoflagellates, chlorophyceae and cyanophyceae was mainly restricted to the river mouths and their surrounding waters. Evaluation of the trophic state (Marine Trophic Index TRIX) revealed that Jakarta Bay was the most eutrophied system, followed by Lampung and Semangka Bay. However, within each bay, distinct areas with different trophic levels could be distinguished, being highest near the coast. In total, spatial variability of parameters were much more pronounced than temporal variability, which is in keeping with the moderate meteorological fluctuations typical for tropical regions.
|Schlagworte:||Anthropogenic nutrient enrichment, eutrophication, nutrient dynamics, phytoplankton dynamics, chlorophyll-a, primary production, trophic state, tropical ecosystem
Bucht von Jakarta ; Phytoplankton ; Autökologie ; Lampungbucht ; Semangkabucht