Thermal acclimation influences the growth and toxin production of freshwater cyanobacteria

A central goal of aquatic science is to understand the ecological factors that promote harmful cyanobacterial blooms, especially in light of climate change, which is altering the temporal variability of water temperature, in addition to increasing mean temperatures. However, we have yet to consider how this variability affects cyanobacteria populations that may more gradually adjust their physiology (acclimate) relative to the pace of temperature change. Using laboratory experiments, we show that acclimation dramatically affects the growth and toxin production of cyanobacteria exposed to different temperature perturbations. This occurs in both oligotrophic (low-nutrient) and eutrophic (high-nutrient) conditions. Thus, changes in the thermal structure of aquatic habitats may interact with organismal physiology to determine the frequency, severity, and harmful effects of cyanobacterial blooms.