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Lake Brokopondo (officially named Prof. Ir. W.J. van Blommensteinmeer) has been constructed for generating electricity, which is used for smelting aluminium from bauxite. Near Afobaka a dam was built across the Suriname river, and after closing the gate on February 1, 1964 the lake began to fill. An area of approximately 1,560 km2 of tropical forest was inundated (Fig. 1). The implications for water quality, fish fauna and vegetation were studied during the filling up of the lake. In this chapter some of the results of the hydrobiological observations are given. A short summing up of the events will be given here. In the first years of water stagnation an enormous development of floating vegetation (Eichhornia crassipes) occurred, which has been controlled by spraying the herbicide 2-4-D. Characteristic plankton species from the flowing Suriname River did not survive after stagnation. Also bottom dwelling macrofauna and fish died as a result of oxygen depletion by the rotting forest. Navigation on the lake became dangerous as subsurface tree trunks or floating logs became a risk. Wind action increased causing high waves. Below the dam in the lower course of the Suriname River the salinity increased as the sea water in the tidal region reached higher up. At the port silt sedimentation increased. As to the use of water from the lake, it should be mentioned that the turbines were affected by the aggressive, acidic water. This also caused corrosion of the shells of snails and bivalves in the river and lake. The snail Biomphalaria glabrata, which is a host for bilharzia, is absent in this lime poor environment. |
