An overview of historical harmful algae blooms outbreaks in the Arabian Seas

•Arabian Seas have complex physical and biological features.•HABs have occurred frequently in the Arabian Seas during the last decade.•HABs outbreaks over the Arabian Gulf are caused mainly by anthropogenic activities.•Diatoms and dinoflagellates are the most produced species over the Arabian Seas. Harmful algae blooms (HABs), often composed of oceanic plants called phytoplankton, are potentially harmful to the marine life, water quality, human health, and desalination plants, a chief source of potable water in the Arabian Gulf. The last decade has seen a noticeable increase in the frequency of HAB outbreaks in the Arabian Seas. This increase is mainly caused by the unprecedented economic growth in the region. The increased human activities in the region have added more stress to the marine environment and contributed to the changes observed in the properties of the marine ecosystem: high temperature and salinity, high evaporation rates, limited freshwater inflow, shallow nature, pollution. However, very few studies that cover the HAB outbreaks, causes, impacts and biological characteristics over the region have been published. This work presents a comprehensive overview of historical HAB outbreaks recorded in the region, and investigate their causes and impact, and seasonal variability.