What impact can excessive phosphorus from fertilizers have on a water body?

Excessive phosphorus from fertilizers can significantly impact water bodies by causing eutrophication and promoting algal blooms. Eutrophication occurs when nutrient levels, particularly phosphorus, increase in aquatic environments, which stimulates the growth of algae. This rapid growth often leads to algal blooms, which can deplete the oxygen in the water as they die off and decay. The result is a decline in water quality, which can harm fish populations and other aquatic life. Eutrophication can create dead zones in the water where oxygen levels are too low to support most marine life, leading to ecosystem imbalances and biodiversity loss. Thus, the connection between surplus phosphorus and harmful algal blooms highlights the importance of managing nutrient runoff to protect aquatic environments.