The Lake Volta Project: Outcomes and Capacity Building:

Predictive modelling:

Lake Volta Landsat

1: Determination of the fate and mode of aquaculture waste dispersal in the Lake

Cage aquaculture is very susceptible to external water quality problems and the success of it depends on maintaining good water quality. A previous study (Asmah et al. 2011) did not show significant variations in water quality between the current water quality results and those obtained two decades earlier. There was, however, indications of nutrient enrichment downstream of the Lake and which had led to proliferation of aquatic weeds at these sections of the Lake. The source of nutrients could not be attributed to aquaculture upstream of the Lake as there was no evidence to support such an assertion. Solid wastes emanating from cage farms consist of particles of varying sizes and densities and with varying settling velocities. These particles are affected by water currents that may vary with depth and the resulting dispersion may cause settlement well away from the farm (Scottish Executive Central Research Unit, 2002). The eventual site of deposition depends on local bathymetry, water movement, and flocculation. Bacteria may break down slowly settling particles, leading to the release of nutrients into solution. A solid waste dispersion model has been used to track particles to the water bed and the fate of the particles determined in an effort to predict the potential zones of organic enrichment.

2: Development of predictive models of the effects of cage culture on the lake

The information gathered from the studies listed above are being analysed and collated to provide both an overview of the environmental impact of cage aquaculture in the Lake and an appropriate data set to drive and validate a predictive model of cage farm effects on the lake.