Green tides are usually induced by water eutrophication. An acceleration of chemical inputs that influence algal population, especially Ulva. The increase of nitrogen and phosphorus is the main factor in green tides. Ulva is very efficient to proliferate by fragmentaion and creates such blooms, some species were documented on green tide occurrences in several regions, namely: Ulva lactuca, U. rigida, U. olivascens, U. gigantea, U. curvata, U. rotundata, U. scandinavica, U. pseudocurvata, U. armoricana, U. prolifera, U. reticulata. Generally, green tides have negative impact on marine ecosystem, human health and economic. Green tides also impact the fishing and aquaculture activities, dead alga can produce hydrogen sulfide which can cause animals and humans death