par Smorygo, Aleksandra 
Promoteur Dahdouh-Guebas, Farid
Co-Promoteur Trevathan-Tackett, Stacey;Sherman, Craig
Publication Non publié, 2024-08-29
Promoteur Dahdouh-Guebas, Farid
Co-Promoteur Trevathan-Tackett, Stacey;Sherman, Craig
Publication Non publié, 2024-08-29
Mémoire
| Résumé : | Seagrass beds are critical marine ecosystems facing multiple stresses related both to naturalprocesses and anthropogenic activity. However, the exact causes of global seagrasses declining arenot always clear. Seagrass wasting disease (SWD) is considered to be responsible for massiveseagrass declines in the past, and still remains a serious threat to seagrass ecosystems worldwide.Stramenopile protist Labyrinthula spp. that can act as a SWD causative agent is associated not onlywith seagrass plants, but also floating mangrove leaf litter. Considering Labyrinthula ecology, it isnot yet known if these organisms are facultative or obligate, host-specific or general seagrasspathogens. Environmental conditions that may affect seagrasses resilience should also be takeninto consideration for resolving SWD etiology. Therefore, in this thesis we evaluated thesusceptibility of Southeastern Australia seagrass Zostera muelleri to Labyrinthula infection understress conditions, in particular - increased seawater temperature and the removal of a leafmicrobiome. Two Labyrinthula isolates obtained from seagrass meadows tested positive forpathogenicity, while a Labyrinthula strain isolated from mangrove leaves did not demonstrate astrong ability to cause the disease. No significant difference in disease development was foundbetween the samples treated with elevated and normal temperatures, as well as between thesamples with and without their leaf microbiome. Although we assume that SWD progression is notaffected by the temperature changes in winter and the presence of a leaf microbiome, thepresence of pathogenic Labyrinthula in Victorian seagrass meadows indicates the necessity of constant seagrass health monitoring |
