Opinion paper National and international public policies for the management of harmful algal bloom events. A case study on the Brazilian coastal zone N.O. Castro a, * , P. Domingos b , G.A.O. Moser a a Faculty of Oceanography, Rio de Janeiro State University, S~ ao Francisco Xavier Street, 524, Maracan~ a, Rio de Janeiro, RJ, Brazil b Roberto Alcantara Gomes Biology Institute, Rio de Janeiro State University, S~ ao Francisco Xavier Street, 524, Maracan~ a, Rio de Janeiro, RJ, Brazil article info Article history: Received 1 December 2015 Received in revised form 12 March 2016 Accepted 25 April 2016 Available online 5 May 2016 Keywords: Brazil Environmental management Eutrophication Microalgae Toxins abstract The expression Harmful Algal Blooms (HABs) includes toxin-producing species and those that produce biomass in sufficient quantities to significantly reduce the concentration of dissolved oxygen in the water column and cause mortality events for other marine organisms. Originally a natural phenomenon, these blooms are becoming more frequent and persistent due to the impact of the anthropogenic action caused by the transport of exotic organisms through ballast water and mainly by the eutrophication of coastal waters as a consequence of the discharge of untreated domestic and industrial effluents. In order to highlight the delays of the Brazilian environmental public policy regarding the issue of HABs on its coastal zone, and what can be improved, a review of the main causes and impacts of the phenomenon is performed, as well as shown how other countries in the world have advanced on the subject. To develop an appropriate and effective policy that can provide the necessary environmental safety, multiple stakeholders are necessary in order to achieve proper procedures and limits for each region. To do so, it is important to carry a dialogue among different government levels, responsible for the reduction of pollution over the river and coastal systems. In addition, the implementation of a greater debate among the scientific community, in order to better establish legal limits that each toxin or potentially harmful species should have in different means of exposure, and the stimulation of a greater involvement of the coastal community in monitoring and alerting cases of HABs must be considered. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The phytoplankton, in addition to being responsible for pro- ducing much of the available oxygen in the atmosphere, has a unique ability to quickly respond to the physical and chemical variations of the water column, which ends up making it one of the best environmental indicators (Cerme~ no et al., 2006; Susini-Ribeiro et al., 2013). It is exactly through the bloom of some species (in- crease in the number of organisms during a short period of time) and consequent reduction in water quality, that important an- thropic disturbance levels can be observed in the marine environ- ment (Heisler et al., 2008; Li et al., 2014). It's important to mention that not all algal blooms are poten- tially harmful (e.g. Picocyanobacteria generally occur in oceanic waters with densities higher than 10 6 cells l 1 and do not cause deleterious effects on other components of the marine trophic web) (Fenchel, 2008). Likewise, not all synthesis of toxic compounds is linked to the occurrence of high cell concentrations (e.g. species of Dinophysis can induce diarrhetic symptoms with at least 10 2 cells l 1 )(Sellner et al., 2003). Density increase of phytoplankton can be directly related to light and nutrients availability in water column. On the other hand, toxins synthesis is still under discussion and many causes have been addressed in literature, such as hydrody- namic conditions, availability of inorganic nutrients, need for organic compounds, allelopathic competition or defense mecha- nism against predators (Flynn, 2008; Gran eli et al., 2008; Sol e et al., 2006). Despite the fact that Harmful Algal Blooms (HABs) can occur naturally in the oceans, recent increases in the frequency of occurrence, geographical extent and duration of HABs have been associated with the increase of the availability of nutrients in the first meters of the water column (eutrophication) - caused by the discharge of effluents on the coastal zone e and the introduction of exotic and harmful species with the ballast water of ships (Anderson, 2009; Lewitus et al., 2012; Mas o and Garc es, 2006). The HABs are classified in two categories, according to the main negative impacts associated. The first type is related to water quality loss caused by excessive increase on turbidity and dissolved * Corresponding author. E-mail address: nathaliaocastro@gmail.com (N.O. Castro). Contents lists available at ScienceDirect Ocean & Coastal Management journal homepage: www.elsevier.com/locate/ocecoaman http://dx.doi.org/10.1016/j.ocecoaman.2016.04.016 0964-5691/© 2016 Elsevier Ltd. All rights reserved. Ocean & Coastal Management 128 (2016) 40e51