Peridinium quadridentatum (Dinophyceae) is an occasional daily diurnal surface forming algal bloom species in Veracruz, Mexico

It has been 19 years since the first bloom of the non-toxic dinoflagellate Peridinium quadridentatum
was recorded in Veracruz, Mexico. Since then, recurrent blooms have occurred in Veracruz
central coast, specifically in the port of Veracruz and Boca del Rio, the most important cities
with an extended urban coastal zone. Prior to the first reported P. quadridentatum blooms, the
cause of discoloured water in southwestern Gulf of Mexico were recurrent blooms of the toxic
dinoflagellate Karenia brevis. Though not toxic, P. quadridentatum blooms cause hypoxia and
significant water discolouration which is unappealing to beachgoers. We analysed the information
generated through 13 years of observations of P. quadridentatum blooms in different studies in
Veracruz including: occurrences, annual dynamics, and diel behaviour of the species. Peridinium
quadridentatum blooms at the beginning of the rainy season when salinity decreases, with warm
water temperature, with cell abundances increasing during the day and under a relatively high
Redfield ratio of dissolved nutrient concentrations where N is not limiting. We believe that the
benthic-planktonic habitat and the vertical migration of this dinoflagellate is favourable for the
daytime blooms. We characterized the blooms of P. quadridentatum as an occasional daily
diurnal surface (ODDS) forming harmful algal bloom species in Veracruz.