Why do Harmful Algae Blooms Occur?

​HABs largely occur because of an unnatural increase of Nitrate and Phosphate in a body of water (also known as Nutrient pollution), warm water temperatures, and weak water currents. Nitrate and Phosphate are essentially two nutrients that all living organisms needs for growth and reproduction. They can be found in human/animal feces and are a large component of most fertilizers [11]. Population growth has placed greater demands on the agricultural industry which has caused for an increase in fertilizer use amongst farmers. In the past five decades, global use of Nitrate based fertilizer has increased 20 folds and the global use of Phosphate based fertilizer has increased 4 folds [12].  The “Industrialization of Agriculture” has also seen the development of Concentrated Animal Feed Operation (CAFOs) which cause for massive amounts of manure being produced in a relatively small area. Application of fertilizer on fields and animal waste from CAFOs results in nutrient discharge, which is the downhill flow of excess nutrients due to rainfall. Since major sources of nutrient pollution are non-point, such as farms, they are harder to regulate and control. The presence of these excess nutrients in a body of water “overfeeds” the algae in the body of water and causes for large Algae Bloom [13].