 It is thought that the poor water quality is due to increased light and oxygen competition from algae.Farming fertiliser runoff release nitrogen, phosphorus, and potassium into the oceanic ecosystem, these limiting nutrients cause massive algal growth which leads to depletion in oxygen available for other creatures which decreases the biodiversity in the affected areas, altering the species composition.A study by Katharina Fabricius and Glen Death of Australian Institute of Marine Science found that hard corals numbers were almost double on reefs that were far from agricultural areas.