Runoff from domestic, industrial, and agricultural processes is the primary cause of nutrient overloading in aquatic ecosystems. Nutrient pollution is a significant problem which is only set to increase as global food demand increases and, with it, fertilizer use. Excess availability of nutrients such as nitrogen and phosphorus (two of the primary components of agricultural fertilizers) in stagnant water (eutrophication) drives the growth of phytoplankton and, subsequently, the formation of harmful algal blooms (HABs). 

According to the FAO, around 40.25 million tons of nitrogen already enter the ocean annually, accounting for around 35% of the weight of mineral nitrogen fertilizers used globally every year.

Eutrophication resulting from nitrogen emissions to fresh and marine waters globally