Provided herein are exemplary methods for controlling a density of algae growing in an aquatic environment. Some exemplary methods include applying an effective amount of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) to the density of algae growing in the aquatic environment, wherein the algae includes genus Nannochloropsis. The algae may also include algae of genus Tetraselmis and/or genus Chlorella. Applying the effective amount may result in an approximate concentration of between 100 nanomolar to 1500 nanomolar DCMU in the aquatic environment. Further, the aquatic environment may include seawater, freshwater, or mixtures thereof.
