Authors

E CHAILLER¹; M Perennou²; S Itoïz²; H Le Bayon¹; M Smits²; E Derelle²; A Bidault²; N Le Goïc²; P Soudant²; A Chambouvet¹;  ¹ CNRS, Sorbonne University, France;  ² Univ Brest, CNRS, IRD, Ifremer, LEMAR, Plouzané, France, France

Discussion

Thraustochytrids (Labyrinthulomycetes, Stramenopiles) are enigmatic heterotrophic unicellular protists which are ubiquitous and abundant in a wide variety of environments. Their ecological role remains largely unknown and underestimated, yet these osmo-heterotrophic protists play a fundamental role in the cycling of organic material as they have the ability to degrade numerous organic substrates including refractory organic matter. Even if, for now, the majority of described Labyrinthulomycetes are saprotrophic, some members have been described as parasites or pathogens and implicated in mortality events of numerous benthic invertebrates or algae. One hypothesis is that some of these organisms can be opportunistic parasites that become pathogenic in host stress conditions. Global biodiversity is currently threatened by anthropogenic eutrophication of environments, increasing temperatures, and biotic factors; these factors can weaken organisms and make them vulnerable to pathogenic agents such as opportunistic parasites like thraustochytrids. This is the case of Manila clam populations (Ruditapes philippinarum) which are threatened by another unicellular exotic parasite, Perkinsus olseni (Perkinsea, Alveolata). Accidentally introduced into Europe from Asia with its host, P. olseni spread along the European Atlantic coastline following a latitudinal gradient with recurrent mortality events in Spain and Portugal. The aim of this poster is to evaluate the genetic diversity and the distribution of novel Thraustochytrids associated with P. olseni-infected clams along the French Atlantic coastline.