Lakes have been created on phosphate mine lands in
Results/Conclusions
Water conductivity, pH, turbidity, and surficial dissolved oxygen were similar among all age/design categories. Chlorophyll a concentrations were characteristic of natural eutrophic lakes of the area and increased only slightly in older lake categories. Sediments of newly created lakes were dominated by either sand or clay. Profundal sediments of lakes over 5-10 years old displayed increased organic matter accumulation. Littoral sediment composition differed greatly among lakes and was determined by bank slope, density and composition of the vegetation community. Lake stratification was a function of maximum depth and not related to bottom configuration complexity. It appears that phosphate lakes do not undergo an initial trophic surge commonly experienced in new reservoirs. Their unique geological location on top of phosphate deposits coupled with Cyanobacterial dominance ensures constant high productivity along the age gradient. Conservative water quality parameters, such as conductivity, seem to be independent of lake age or design. Turbidity also displays stability; however, a shift from clay suspension in young lakes to Cyanobacterial dominance as age progresses is indicated. Thus, phosphate lakes appear to undergo no noticeable ecological succession during the first 30-40 years following creation.