Eutrophication describes the enrichment of an ecosystem with chemical nutrients (nitrates, phosphates, etc.)

• The nutrients can be introduced into waterways via leaching from soil by rainfall or released as part of sewage
  

• Eutrophication is common around agricultural lands where the use of artificial fertilisers are prevalent
  

An increase in nutrient supply within aquatic and marine ecosystems will result in several ecological consequences:

• A rapid growth in algal populations will occur (algal blooms) as a result of the increased availability of nutrients
  

• As the algae die, there will be a subsequent spike in the numbers of saprotrophic microbes (decomposers)
  

• The high rate of decomposition will result in an increased biochemical oxygen demand (BOD) by saprotrophic bacteria
  

• The saprotrophs will consume available quantities of dissolved oxygen, leading to deoxygenation of the water supply
  

• Eutrophication will also increase the turbidity of the water, which will reduce oxygen production by photosynthetic seaweeds
  

• This will stress the survival of marine organisms, potentially leading to a reduction in biodiversity within the ecosystem
  

Eutrophication