Multi-year succession of cyanobacteria blooms in a highland reservoir with changing nutrient status, Guizhou Province, China

Over the last 22 years significant phytoplankton changes in Hongfeng lake reservoir have been observed with multiple years of harmful cyanobacteria blooms (cHABs). Fish farming and other anthropogenic activities from 1994-2001 triggered the harmful blooms. Nine years after the cessation of aquaculture, a conversion from problematic species (Microcystis spp, Aphanizomenon flos-aquae) to the less problematic species P. limnetica and other associated non-cyanobacteria taxa was recorded. Through this period of change, trophic factors (bottom-up) were re-examined, and correlations between cHABs and selected environmental variables were observed. Higher temperatures, nutrients (TN, TP) and available light significantly favored the development of Microcystis spp blooms. With declining nutrient loads, and a decline in TP relative to TN there was a competitive shift from Microcystis summer blooms to the growth of Pseudanabaena limnetica and other non-cyanobacteria. Pseudanabaena limnetica was favored over Microcystis spp when temperatures were