Evaluation Of Batu Bumbun Sanctuary Ecosystem And Management Strategy Affected By Climate Change In Mahakam Watershed, Kutai Kartanegara, Indonesia

Abstract

ABSTRACT: Batu Bumbun Sanctuary (Middle Mahakam Lake) is very important for the fishermen community and Mahakam Irrawaddy Dolphin life concerned to its function as the source of fish and as the feeding ground of Irrawaddy Dolphin (Orcaella brevirostris). The changes in the forest function and the climate (such as rainfall and water surfaces) are predicted to have caused suppression in the ecosystem of Batu Bumbun Sanctuary. The aim of this study is to evaluate the current ecosystem changes of Batu Bumbun Sanctuary and suggest a suitable management strategy as a way to conserve its function. The research was conducted during the dry season (April – June) and rainy season (November – December) 2014, by using survey methods. The measured parameters were including water quality (DO, pH, temperature, TSS, TDS, alkalinity, and clarity), vegetation composition, rainfall, water surface elevation, and sediment. The data of fish community were analysed by using Shanon-Wiener index. The result showed that: (1) The current condition of Batu Bumbun biophysical ecosystem has been experiencing a heavy degradation, showed by a high fluctuation of the water surface in two extreme seasons such as the flood in rainy seasons and silt up in the dry season. (2) The vegetation composition in the riverbanks was composed of five species including Bungur (Lagerstroemia speciosa), Rambai Punai (Chaetocarpus Castano carpus), Kendikara (Dillenia excelsa), Kademba (Mytragina speciosa), and Rengas (Gluta renghas). The dominant tree species was Putat (Barringtonia asiatica) and Perupuk (Lophopetalum javanicum). (3) Batu Bumbun Sanctuary has been experiencing a heavy siltation caused by silt material that piles up the weeds during the rainy season. Since 1985, Batu Bumbun was predicted to have rates of silting around 8 cm/year. From those result, it can be concluded that Batu Bumbun has been experiencing a heavy degradation showed by a high fluctuation of water surface, vegetation composition, and heavy siltation. Then, the most suitable suggestion for its management was (a) dredging, (b) revegetation, (c) restocking native fish, (d) establishing an appropriate institute, (e) preventing illegal fishing, and (f) increasing its security.