Excessive use of fertilizers has little impact on aquatic life. explain.

Fertilizer contains different types of phosphates and nitrates. When they are used to fertilize large fields, it can be beneficial in the matter of food production. But when it rains those nitrates, phosphates, etc can run off into a river,lake,stream and cause eutrophication . 

Eutrophication causes an abundance of plant growth such as algae blooms. Algae blooms can suffocate fish and can have an impact on human health. 

Wetlands form where water and land meet. a lake with a wetland fringe can fill in with decayed plant and animal material to become a wet meadow. a pond can fill in to become a bog or fen. sediment can fill in a river marsh to become a swamp.flooding of coastal lowlands from rising sea levels has created broad coastal marshes that are protected from wave action by barrier islands or reefs. coastal wetlands also form when rivers deposit sediment as they reach the ocean. plants then take root and hold the soil firm against the forces of tides and waves.