Causes of Eutrophication

Algal blooms and eutrophication are basically caused by an excess of nutrients being added to the system. Mainly, these extra nutrients are anthropogenic, stemming from human activity. Stormwater runoff carries such things as fertilizers into lakes and rivers, which all eventually lead to the ocean. These fertilizers are filled with phosphates and nitrates, two limiting nutrients that algae feed on. Once these enter the water column, it is only a matter of time before an algae bloom occurs. The fertilizers can be manmade agricultural fertilizers or “natural” fertilizer from livestock – the former is more potent, but both are prevalent in our waterways.