Abstract |
This report reviews the literature concerning the consequences of nutrient enrichment, the significance of phosphorus in eutrophication, critical phosphorus concentrations, the effects of eutrophication on human populations, and the extent of the eutrophication problem in the United States. The evidence contained in this report indicates that (a) excessive nutrient concentrations are associated with undesirable changes (eutrophication) in aquatic plants, depletion of dissolved oxygen, disappearance of cold water fish, and appearance of nuisance algal species; (b) excessive phosphorus is most frequently responsible for these undesirable changes in lakes; (c) lakes and reservoirs respond more severely to excessive phosphorus concentrations than do flowing waters, and do so at lower phosphorus concentrations; (d) phosphorus may at times be the limiting factor in estuaries but is not usually the limiting factor in coastal waters; (e) critical phosphorus levels which lead to eutrophication have not been clearly defined because of the variation in the response of surface waters to phosphorus caused by differences in residence times, (f) eutrophication has adversely affected human populations through increased water treatment costs, decreased property values, changes in the commercial fishery and reduction of the aesthetic and recreational values of affected lakes. |