Effects of a Cyanobacterial Toxin and Macrophyte composition on Amphibian Parasitism
thesisposted on 23.05.2021, 09:21 by Marin Milotic
Amphibians are experiencing global declines with habitat loss and degradation, and infectious diseases as major contributors. Environmental changes such as eutrophication and climate alterations can cause the proliferation of primary producers, including cyanobacteria, and both native and invasive macrophytes. Cyanobacterial blooms can be toxic due to the production of microcystins such as MC-LR, and invasive macrophytes can alter the structural complexity of aquatic habitats – both can affect host-parasite dynamics. I examined the effects of MC-LR on larval amphibian susceptibility to infection by a trematode parasite as well as host growth and anti-parasite behaviour, finding increased susceptibility to infection at low concentrations. I also investigated how MC-LR affected the longevity and activity of trematode infectious stages (cercariae), and demonstrated variable effects among species. Lastly, I examined how environmental structural complexity, modeled as macrophyte complexity and density, affected tadpole infection by a trematode parasite and host anti-parasite behaviour but found no impact.