Although fish farming provides numerous benefits in the areas of employment, food security, nutrition, trade, and foreign exchange, among others, intensive cage culture operations could cause environmental pollution. The influence of cage culture operations on the quality of the physical and chemical variables in the water column of Lake Volta in Ghana was assessed in this study. The physical and chemical variables were measured from April 2013 to March 2015 following analytical procedures described in the standard methods for the examination of water and wastewaters. A noticeable decrease in oxygen and temperature was observed with increasing depth. No major variances in concentrations of nitrate, nitrite, ammonia, phosphate (dissolved nutrients), chlorophyll-a, dissolved oxygen, secchi depths, and total suspended solids between the cage site and the reference site were detected. There seemed to be no considerable cage impact on the water perhaps due to dilution and the water currents of 0.061 ms-1 which was capable of dispersing wastes from the cages. Consumption of waste feeds by wild fishes which gathered in the vicinity of the cage also contributed to the reduction of the impact. In addition, uptake of inorganic nutrients by phytoplankton and microalgae, biological and physical interactions could account for the low impact.
Key words: Cage culture, physico-chemical variables, water quality, environmental pollution, Volta Lake, fish farming.
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