During toxic algal blooms, shellfish accumulate toxins, becoming unsafe for human consumption and leading to shellfish harvesting closures that can strongly impact the aquaculture industry. Understanding the factors influencing toxicity in shellfish is therefore an important public-health and socio-economical challenge. I will present here the results of experimental exposures to toxic dinoflagellates that highlighted how farming practices and shellfish pathological condition can impact phycotoxin accumulation and metabolization in the shellfish flesh.
In addition to the threat to human health, harmful algal blooms (HABs) can alter shellfish physiological functions. The impacts of HABs exposure on immune variables, particularly, have suggested they could increase disease susceptibility. I will address the effects of Alexandrium spp. exposure on pathogen infection in oysters. Effects on different examples of host - pathogen interactions will be discussed.
These results provide a better understanding of the involvement of toxic algal blooms in the development of diseases affecting commercial bivalve species, but also highlight the complexity of these interactions.
Finally, I will mention my research perspectives within the frame of my future position at ODE/UL/LER-BO, Ifremer Concarneau, to investigate new ichtyotoxic algae (producing unregulated compounds, harmful to marine fauna) and their effects on commercial marine organisms.