The Eutrophic waters favor quickly developing plants and algae's. These long living species cannot resist competition and develop into oligo or mesotrophic waters which make these waters of less interest in terms of biodiversity and ecological quality. Thus they die of indigestion. The process of eutrophication is clearly described by the following figure;
The main cause of eutrophication is large input of nutrients to the water body and its effect is on imbalance of the food web which results in high levels of phytoplankton biomass in stratified water bodies. This can lead to algal blooms. The direct consequence is an excess of oxygen consumption near the bottom of the water body. Additional factors supporting this process are
Along with carbon, oxygen and hydrogen which plants get from water they also need nitrogen and phosphorous which are necessary for the development of aquatic life thus during eutrophication the concentration of nutrients in the water changes, phosphorous is usually a limiting factor for phytoplankton in fresh water, large marine areas have nitrogen as limiting nutrient especially in summer. Intermediate areas such as river plumes are often phosphorous limited during spring.
Once eutrophication is detected in the water body it is considered sensitive under the European Union Urban waste water treatment directives and is declared nitrate pollutant according to the Nitrate directive and is an indicator of disturbed ecosystem. A healthy ecosystem is the ecosystem that functions well and is able to resist or recover from disturbance. The organization of the ecosystem refers to the food web and the biodiversity; ecosystem resistance is the non-response, up to a certain extent, of impacts such as nutrient enrichments. The ecosystem elasticity refers to the ecosystem ability to survive through the applied pressures. Although all these ecosystem characteristics contribute to the ecosystem health and integrity, they induce a non-linear response to the ecosystem which complicates the quantification of the assessment. The initial effects from eutrophication are negligible as they are below the carrying capacity: any measurable effects are less pronounced than seasonal fluctuations and therefore, any assessment seems to be uncertain. As the phenomenon of eutrophication is getting established, changes in mean nutrient and chlorophyll concentrations as well as changes in the community structure become obvious. This stage can be the early warning for the ecosystem quality.
Human activities are main cause of eutrophication all around the