a) A primary succession begins with the growth of lichens which dissolves the bare rock and cause weathering of rocks which results in soil formation. Then small plants like mosses can inhabit followed by herbs, shrubs and then trees. Finally, a stable climax community evolves. b) Algal bloom causes increase in the number of algae in the water body. This might be due to the entry of industrial waste into the water bodies. Algal bloom increases BOD, resulting in the death of fish and aquatic life in the water bodies.