How does algal bloom destroy the quality of a fresh water body? Explain. (3)
Increased concentrations of phosphates and nitrates from industries, residential wastes and from agricultural run off water into the water bodies result in excessive growth of algae which form a mat on the surface of water. This phenomenon is called algal bloom or eutrophication.
It affects the ecosystem in the following ways:
1. It deteriorates the water quality and fish mortality.
2. It results in depletion of dissolved oxygen resulting in death of aquatic life.
3. Nitrates contaminate drinking water leading to decrease in oxygen carrying capacity of haemoglobin in human beings.