Seasonal variations in the concentration of microcystin-LR in two lakes in western Texas, USA

Seasonal variations in the concentration of microcystin‐LR (MCLR) in Buffalo Springs Lake (BSL) and Lake Ransom Canyon (LRC; both locations in Lubbock, TX, USA) were monitored from 2003 to 2004. In BSL, the average concentrations of MCLR were 1.78 ± 1.43 μg/L (mean ± SD; range, 0.177–4.914 μg/L) in spring, 0.41 ± 0.096 μg/L (range, 0.191–0.502 μg/L) in summer, 0.46 ± 0.41 μg/L (range, 0.205–1.598 μg/L) in fall, and 1.04 ± 0.71 μg/L (range, 0.096–2.428 μg/L) in winter. In LRC, the corresponding concentrations were 1.08 ± 1.29 μg/L (range, 0.2–5.83 μg/L) in spring, 0.83 ± 0.46 μg/L (range, 0.315–1.671 μg/L) in summer, 0.44 ± 0.03 μg/L (range, 0.368–0.555 μg/L) in fall, and 0.78 ± 0.52 μg/L (range, 0.225–2.130 μg/L) in winter. In both lakes, the seasonal fluctuation of MCLR concentrations correlated positively with dissolved oxygen and negatively with temperature and pH.