Lake Sentani, Indonesia III
Preliminary bottom sediment samples from the eastern part of the lake have recently yielded sparse populations of arcellacean microfauna, dominated by Centropyxid types (R.T. Patterson, pers. comm., 1995). In North America these species are found associated with brackish or polluted water conditions, raising the possibility that there is residual (?) salinity in the deeper parts of the lake.
Many of the Sentani people, who inhabit the islands, perimeter and environs of the lake, still have a traditional subsistence economy based on fishing and sago harvesting. This has been sustainable for centuries but local reports suggest that catch yields have diminished in recent years. Whether this is a result of overfishing (as a result of population growth and/or market pressure), pollution or introduction of foreign species is not established. Many of the residents occupy dwellings built on posts over the lake, which thus serves as a depository for sewage, leading to locally high coliform counts (Daawia, 1992; I Made Budi et al., 1994) but also to nutrient enrichment. Water hyacinth (Eichornia crassipes), introduced since the early Seventies, has become a major plant pest and may be contributing to decline of some species.
Much of the mountainous terrain between the north shore of the lake and the ocean falls within the Cyclops Strict Nature Reserve. The future management of the reserve and buffer zone, and the environmental quality of the lake, are strongly interdependent. Recently a major reforestation project of grassland on the slopes surrounding the lake has been initiated, with the support of forest companies operating in Irian Jaya.
A major sustainable development issue for the inhabitants of the lake and surroundings is the existing proposal to build a hydroelectric generating facility, by means of a dam on the Jafuri River to divert the lake drainage eastward through a canal to a power station and thence to an outlet at the sea in Yotefa Bay near Jayapura. Several feasibility and environmental impact studies (e.g. Environmental Study Centre, UNCEN, 1984) have yet to totally define the cost/benefit consequences of this project.
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