Gradients of anthropogenic stress in Indonesian coral reefs Implications for bacterial community composition and aggregate formation

Abstract

The Indonesian Spermonde Archipelago, like other coral reefs located in close vicinity to urban areas, is confronted with a multitude of local anthropogenic stressors. A combination of experimental and observational studies was conducted at several fringing reefs and in the water column of the Archipelago during two sampling campaigns. Water quality parameters were not gradually decreasing with increasing distance from Makassar. Instead, there were two contrasting regions, one eutrophic inshore zone and the remaining, oligotrophic shelf. Bacterial community compositions were very distinct between those two described zones. Additionally, significantly higher total aggregated volume and sedimentation rates were observed in the eutrophic zone compared sampling within the oligotrophic outer shelf zone. Data presented in this thesis conclusively showed that dense human populations on the mainland and on the individual islands exerted a clear and measurable influence on the investigated water quality parameters, but that influence was restricted to a narrow zone close to the coast.