The Eutrophication Process
Diagram exemplifying eutrophication in coastal water bodies. The process begins with excessive inputs of nutrients (primarily N and P) into the system. These nutrients lead to a substantial increase in primary production (e.g. macroalgae) which eventually results in the transport of vast amounts of organic material to the seabottom. Subsequently, oxygen consumption increases dramatically as organic material starts to decompose while vertical delivery of oxygen through the water column is restricted by thermal and/or saline stratification (i.e. pycnocline). Bottom-dwelling organisms suffocate and/or migrate to other areas.
Credit: Pew Trusts