Eutrophication is characterized by a rapid increase in plant life that can lead to algal blooms that stop sunlight from penetrating the water body, causing plants below the surface to die. The decomposition of dead plants uses up oxygen in the water. Algal blooms are therefore dangerous to fish because they use up a lot of the oxygen in the water. They can also have a strong, objectionable smell and can affect the taste of water, hence they render the aquatic ecosystem unfit for other uses. Eutrophication increases the cost of water treatment and puts pressure on the water supply budget of African countries. Eutrophication of freshwater habitats increases their vulnerability to invasive alien species such as water hyacinth, which thrives under high nutrient conditions (Reddy et al. 1989; Coetzee and Hill 2012). Water hyacinth is considered one of the world’s most problematic weeds, causing siltation, increased acidity and deoxygenation, among other effects. Several coastal and inland areas of Africa are affected by cyanobacterial (algal) blooms.
From collection: Sanitation and Wastewater Atlas of Africa - Ecosystems