Spatio-temporal distribution, physiological characterization and toxicity of the marine dinoflagellate Ostreopsis (Schmidt) from a temperate area, the Ebre Delta. Phylogenetic variability in comparison with a tropical area, Reunion Island

Laburpena

Harmful algae blooms (HAB) are natural events consisting on proliferations of microscopic algae that have occurred over the history (Hallegraeff et al., 2010). These proliferations may be harmful since some of these microalgae may produce toxins that affect humans through direct exposure by skin contact or aerosols, or through indirect exposure after the accumulation of toxins in seafood (Reverté et al., submitted). Of special concern for this work are outbreaks formed by the benthic dinoflagellate Ostreopsis (Schmidt), including several species producers of palytoxin (PLTX)-like compounds, one of the most potent marine toxins known so far, that may be accumulated in seafood (Munday, 2011). The genus is formed by nine species, though the current state of the taxonomy is controversial, partly due to the lack of genetic characterization of the original holotypes (Penna et al., 2010). A re-examination of the morphological and molecular assignment of each species is reclaimed to create consensus among researchers. The first species was described in tropical areas, however, in recent years, an expansion of the genus to temperate regions worldwide has been observed (Parsons et al., 2012). Of particular interest are O. cf. ovata proliferations, reported more frequently in the last decade, especially in the Mediterranean Sea, where blooms have been associated with human illness (Tubaro et al., 2011) and damage to the benthic ecosystem (Tichadou et al., 2010). In order to better understand O. cf. ovata adaptative dynamics and generate information applicable to future predictive models; latest studies are focused on the determination of environmental factors that trigger massive proliferations. The aim of this thesis is, on one hand, to contribute to the improvement of the genus Ostreopsis taxonomy by molecular, morphological and toxicological characterization of cryptic species isolated in a tropical area and, on the other hand, to investigate, combining field and laboratory analysis, the role of environmental factors and their interaction, involved in the ecology of O. cf. ovata blooms in the NW Mediterranean Sea.