Spatial and temporal variability in benthic food webs of the mangrove fringed Segara Anakan Lagoon in Java, Indonesia

The overall aim of this study was to investigate the influence and importance of benthic communities on the carbon- and nitrogen- flow through the food web in the Segara Anakan Lagoon. I used the method of stable isotope analysis to resolve trophic structures of benthic food webs in several stations within the lagoon. Carbon isotopic compositions were used to trace carbon sources through the food web, whereas nitrogen isotopic compositions help to distinguish between trophic levels. A high spatial variability was found on a small scale, traced back to food availability and possibly also anthropogenic impacts, such as sewage wastes by the city and villages within the lagoon and effluents of the oil refinery. Furthermore, a seasonal area dependent variation was observed, which can be explained mainly by the impact of increased precipitation, and therewith an increased river runoff. As underlying processes of isotopic fractionation are still unclear today, several experiments were conducted to estimate the importance of benthic decapod species on the turnover of carbon and nitrogen in the mangrove ecosystem of the SAL.