Phytoplankton communities in Mediterranean lagoons show a very large amplitude of biomass and cell densities, specially at the picophytoplancton level (picoeukaryotes and cyanobacteria), in relation with eutrophication and salinity gradients. In contrast, the development of harmful/toxic dinoflagellate communities seems to be a phenomenon in extension in coastal marine ecosystems in general, but without a very strong link with environmental variables.
Mediterranean lagoons and coastal marine environments offer a diversity and variability of environments that can allow testing and validation of different models of phytoplankton communities assemblage, as well as growth and survival strategies that are leading to dinoflagellate blooms and their extension.
Our main research theme is the study of toxic algal blooms, particularly the dinoflagellate Alexandrium catenella. We aim to define and understand their origin through their space-time distributions and the description of their biological cycles. Through field observations, in situ and laboratory experimental approaches, we aim to characterize the ecophysiology of these species (inorganic and organic carbon, nitrogen and phosphorus uptake, inorganic and organic nitrogen excretion) and its variability, in part related to their genetic diversity and their interactions with other biological compartments (in particular allelopathic interactions and grazing processes). This work is framed within a more general context of biodiversity of phytoplankton communities (accompanying species or not), in relation with characteristics of lagoon and coastal marine environments. On the short term, this should lead to the definition of bioindicators of the quality of coastal environments. Biological modelling allow to simulate and test hypotheses relating to the succession of life cycle phases and to the use of different inorganic and organic nutrient sources.
Available techniques include flow cytometry, pigment analyses by HPLC, photon and electron microscopy, isotope ratio mass spectrometry coupled to elemental analysis (carbon and nitrogen) and molecular biology techniques.
Alexandrium catenella bloom (Angle Creek, November 2004)