What is eutrophication?

An adequate supply of nutrients (such as Phosphorus and Nitrogen) is essential for the production of food crops both for animal and human consumption. However an excessive supply of nutrients (particularly phosphorus and nitrogen compounds) with subsequent losses to the aquatic environment can lead to adverse effects on both the ecology and uses of receiving waters (i.e. enrichment can lead to a significant decrease in water quality in water bodies). The process of enrichment and its impacts, arising from human activities is termed eutrophication and has been recognized internationally as a significant environmental problem for a number of decades.

Eutrophication generally promotes excessive plant growth and decay, favouring simple algae and plankton over other more complicated plants, and causes a severe reduction in water quality. Enhanced growth of aquatic vegetation and algal blooms disrupts normal functioning of the ecosystem, causing a variety of problems such as anoxia or loss of oxygen in the water with severe reductions in fish and other animal populations (increased incidences of fish kills and loss of indicator fish species such as Arctic char). The water becomes cloudy, typically coloured a shade of green, yellow, brown, or red. Eutrophication also decreases the value of rivers, lakes, and estuaries for recreation, fishing, and aesthetic enjoyment.

In Ireland eutrophication has been identified as an important environmental issue, particularly in fresh water lakes. The concentration of phosphate in rivers, lakes, estuarine and coastal and groundwater bodies in Ireland is a key quality indicator because of its enriching effect as a nutrient (Lucey, 2009).

Further Information

Dr. Fiona Kelly
(Senior Research Officer)
Tel: +353 (0)1 884 2600