RIN INCIDENCE Project

NEMESIS Thesis: Interactions and chemical communication between toxic Pseudo-nitzschia diatoms and primary consumers Pseudo-nitzschia (PN) diatoms are found in many marine ecosystems, including the Bay of Seine. These micro-algae can produce a neurotoxin, domoic acid. As such, they can be responsible for harmful blooms with both health and socioeconomic consequences. Except for the contamination of shellfish and higher trophic levels (seabirds and marine mammals) by domoic acid, the harmful effects of Pseudo-nitzschia in the marine ecosystem are still very little studied. Few data exist on the transfer and impact of domoic acid in the food web, particularly in the mesozooplankton, which is mainly represented by copepods. These organisms can represent a vector for the toxin’s entry into the food web and for the contamination of higher trophic levels. At the same time, it has been shown that the presence of copepods can modulate the toxin production of certain PN species. The study conducted as part of the NEMESIS thesis is the first to explore the existing interactions between toxic diatoms of the genus Pseudo-nitzschia and zooplanktonic primary consumers in the Bay of Seine. Through controlled environment approaches, the reciprocal influence of the two partners will be studied at the physiological and behavioral levels. The chemical communication involved in this relationship will also be studied during this thesis. Finally, an in situ approach will validate the observations made in the laboratory. The NEMESIS thesis, integrated into the INCIDENCE project, will provide information on the influence of the biotic factor on the toxicity and scale of Pseudo-nitzschia blooms in the Bay of Seine. The development of biomarkers for domoic acid exposure in copepods will also be carried out.