The economic losses and health problems caused by Harmful Algal Blooms (HAB) make their understanding fundamental. While the debate continues over whether increased reporting is due to improved monitoring activity or a real increase, HAB are expanding worldwide and they are expected to increase as a result of climate change due to increased sea surface temperature, increased stratification, ocean acidification and eutrophication, mainly in coastal areas. Uruguay I no exception to this trend and in recent years has shown an increase in the intensity of some blooms (higher density and duration), but without changes in its frequency. Species that commonly produced blooms nowadays do so with higher abundance (106 cells / l) and duration (between three and five weeks). The same is occurring with toxic species (e.g. Dinophysis cf. acuminata) determining an extension in time of the mollusks bans, with a maximum of 189 days during 2015. The increase in both space and time of these blooms could be associated with an increase in temperature and nutrient concentration.