Effects of internal loading on algal biomass in Lake Allatoona, a southeastern piedmont impoundment
Ceballos, Elena Louise
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Cultural eutrophication of lakes is the accelerated nutrient enrichment resulting in detrimental ecological effects such as algal blooms, lake anoxia and toxic metal release from sediments. Cultural eutrophication is a common occurrence in Piedmont impoundments in Georgia, as well as lakes and impoundments throughout the world. It often results in water unsafe for agricultural use, recreation and drinking. To reduce the cultural eutrophication of local Piedmont impoundments, recent regulatory controls for nutrients were established as part of the Clean Lakes program and court-ordered total maximum daily loads (TMDLs). These regulatory efforts focus on the reduction and minimization of point-source watershed nutrient inputs, primarily phosphorus, into lake systems, as P is the limiting nutrient in Piedmont impoundments. Thus, reductions in phosphorus loading are expected to improve lake water quality. However, in the Piedmont, as well as worldwide, many lakes continue to experience algal blooms and lake anoxia after sources of external loading are discontinued. The process of nutrient desorption from sediments, known as internal loading, has been identified to be a source of algal-available P, as well as other nutrients. The conditions under which internal loading takes place are region-specific as they vary based on local physical, chemical and biological conditions. The purpose of our research was to quantify changes in algal biomass in response to internal loading in Southeast Piedmont impoundments. The results from a mesocosm experiment, physical and chemical sediment analysis, and algal assays were used to characterize algal-availabile phosphorus in Southeastern Piedmont impoundments.