Review of Possible Causes of Nutrient Enrichment and Decline of Endangered SuckerPopulations in Upper Klamath Lake, Oregon

摘要

Upper Klamath Lake, and the connecting Agency Lake, is a large (140 square mile)lake in south-central Oregon. Typically, the algal bloom causes nuisance and detrimental conditions, including a deep-green 'pea soup' appearance, from mid-May to late October. Ten possible causes for this excessive enrichment in nutrients are described. Three of these hypothesis are suggested for immediate testing because of large-scale changes in nutrient loading that may have occurred as a result of man's activities. These three hypotheses relate nutrient enrichment to (1) conversion of marshland to agricultural land, (2) agricultural drainage from the basin, and (3) reservoir regulation. Eleven possible hypothetical causes for the decline in sucker populations also are described.