Life Cycle of Bloom-Forming Cyanobacteria and its Influencing Factors

Many eutrophic lakes are threatened by cyanobacterial blooms. The bloom-forming cyanobacteria are capable of nuisance growth and produce toxins, resulting in serious threats to water safety and human health. This paper summarized physiological and ecological characteristics of bloom-forming cyanobacteria in their annual life cycle, internal regulation mechanisms and environmental factors for blooms formation. In winter, dormant period is regarded as the continuation of cyanobacteria populations, which conserve “seed bank” for the following year. In spring, recruitment can be defined as an inoculation of overwintering cyanobacteria to the pelagic phase after growth recovery under suitable conditions. Temperature, resuspension and bioturbation had been recognized to be the main driving factors for recruitment. Shortly after recruitment, cyanobacteria establish dominance by fast growth rate and colony enlargement strategy. Under suitable meteorological and hydrological conditions, cyanobacterial colonies aggregate and float up to form heavy blooms, which can lead to water supply crisis and ecological disaster. From late autumn, blooms disaggregate and decline. The sinking process is not only a periodic life cycle but also an irregular mechanical movement. Cyanobacteria accumulation areas in late autumn might highly related to the first occurence locality of blooms in the following year. This information could provide valuable information for the prediction and prevention of cyanobacterial blooms, so as to establish a more stable and healthy ecosystem in lakes.