In nature, algal viruses have been observed to play an ecological role in algal bloom demise. Given this, scientists have proposed that algal viruses have the potential to be used as biological treatments for algal bloom control. For example, a particular algal virus, known as a cyanophage, can be used to control harmful algal blooms of cyanobacteria. Lytic cyanophages are often found in the presence of Microcystis cyanobacteria. Specifically, the impact that cyanophages have on the population control of Microcystis aeruginosa has been a topic of interest given that this species of cyanobacteria is commonly responsible for harmful algal blooms. In one lab study, M. aeruginosa was collected and then treated with cyanophage that was found in the presence of M. aeruginosa in a lake. After six days, the M. aeruginosa algal biomass had decreased by 95 percent. The results of another lab study showed that cyanophages maintain their observed function of algal bloom demise in a controlled eutrophic setting. In this case, the biomass of M. aeruginosa also greatly decreased when treated with cyanophages. A negative correlation between M. aeruginosa and cyanophage has also been recorded in a natural setting. In the freshwater body, Lake Mikata, researchers analyzed samples of M. aeruginosa algal growth and found that the biomass of M. aeruginosa decreased in relation to an increase in cyanophage population density.
