Abstract
The chapter contains studies conducted on the impact of eutrophication on aquatic plant diversity. It covers the concept of eutrophication, its causes and effects on plant diversity within an aquatic ecosystem. A decrease in species diversity and disappearance of aquatic plants were noted in most of the water bodies of the world as a result of eutrophication. The plant diversity in eutrophic ecosystems was studied with special reference to phytoplankton and aquatic macrophytes. Studies on wetlands in western Europe showed that the nutrient enrichment or eutrophication leads to changes in species composition, declines in overall plant species diversity, and loss of rare and uncommon species. The nutrients are the major limiting factors for the aquatic plant diversity. Various environmental factors play a significant role in determining the aquatic plant diversity in a eutrophic ecosystem. In Europe about 17 lakes underwent eutrophication and have lost all or most of their submerged species and favoured the fast growing species capable of regrowth after weeding. The eutrophication process causes succession of macrophytes with complete loss of submerged vegetation and dominance of phytoplanktons. A direct relation was found between the succession of algae and trophic level of the water body. Few studies on measurements of plant diversity such as density, frequency, abundance, and diversity indices are included in this chapter.