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A systematic literature review was undertaken to understand the state and relationship between habitat types and biodiversity in the open coastal Lake Nokoue and to analyse the research gaps towards an efficient management of this ecosystem. Habitat types in Lake Nokoue have been profoundly impacted by the urbanisation around the lake. Kilometres of riparian habitat including mangrove vegetation were destroyed on the south and western shoreline of the lake, removing the natural protection of the ecosystem to the increasing sewage nutrient load. In addition, to this anthropogenic pressure, the solid wastes from the villages on stilts (Ganvie’s villages) increased the nutrient enrichment of the lake. Consequently, the lake experience a seasonal bloom of water hyacinth which dies and sinks to its bottom each year when the salinity rises above 6 ppt. Note that the salinity dynamics of the lake is governed by its hydrological regime which was highly affected by the widening of the sea entrance into the lake around 1960. In addition to these changes, the intensification of the acadja fishing practice has led to the exportation of tonnes of dry woods into the lake. The decay of these woods combined with the accumulation of hyacinth detritus has disturbed the habitats of macroinvertebrates and fish. There is a progressive shift in the system from freshwater species to marine water species and from insectivorous fish to detritivorous fish. Management solutions required reduction of both detritus accumulation and external nutrient load. |
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