Long-term effects of temperature and nutrient concentrations on the phytoplankton biomass in three lakes with differing trophic statuses on the Yungui Plateau, China

Long-term annual (1990-2010) monitoring data were analyzed to test the responses of phytoplankton biomass in three lakes in the Yungui Plateau, China, to increasing temperature and increasing nutrient concentrations. The three studied lakes (Lake Fuxian, Lake Erhai and Lake Dianchi) all exhibited significant increases in algal biomass from 1990 to 2010, with increases of 0.111mg/L, 0.662 mg/L and 3.07mg/L per year, respectively. The study also indicated that the relative influences of warming and nutrient concentrations on chlorophyll a concentration varied among the lakes and was dependent on trophic level and phytoplankton composition. In Lake Fuxian, the increase in algal biomass was correlated with the rapid growth of Mougeotia spp., and the total phosphorous concentration was the key factor driving this increase in algal biomass. In Lake Erhai, the dominant species shifted from Dolichospermum spp. to Microcystis spp. Additionally, the increase in algal biomass in Lake Erhai (involving mainly an increase in Microcystis spp.) was significantly associated with an increase in total nitrogen (TN) concentration. In Lake Dianchi, warming and increases in TN concentration were the strongest predictors of biomass change.