DISEASE CONTROL AND CONSERVATION: APPLYING GRAZING PRESSURE TO SOLVE 'THE WORLD'S WORST WILDLIFE INFECTIOUS DISEASE'

BACKGROUND & TIMELINESS: Naturally occurring diseases threaten ecosystem function, biodiversity, and humans (zoonotic infections). This is especially true for the spread of aquatic borne diseases, which are predicted to be altered by climate-change. Ecologically robust mitigation strategies are needed to tackle this global-landscape issue. To date, efforts have focused on the hosts (e.g. direct treatment) but have had varied success and can damage ecosystem health. Better approaches are required.
NOVELTY: A promising, ecologically sustainable approach is to target the disease's infectious stages at its source, preventing spread across aquatic landscapes. Many animal-diseases are spread by aquatic spores. These nutritious and vulnerable infective stages are then susceptible to aquatic grazers. Enhancing grazing is anticipated to be a valuable mitigation strategy for pathogens of wildlife, livestock, and humans. Understanding, and potentially augmenting, the role of grazers is a new and exciting area of conservation biology.
OBJECTIVES: This PhD will focus on the "worst infectious disease ever recorded among vertebrates": Batrachochytrium dendrobatidis (Bd). This devastating chytrid fungus has caused mass declines in amphibians worldwide. Bd infects via aquatic spores that are consumed by invertebrates and protozoa. Our initial studies suggest that small grazers may be manipulated to mitigate Bd infections, but the direct impact of grazers and the indirect effect of climate change on grazers and Bd remain unknown. To evaluate grazer-control, the study will have five integrated components: 1) field work to survey, isolate, and identify grazers, 2) laboratory work to parameterize a temperature-host-parasite-grazer model; 3) ecosystem modelling to predict grazer impacts; 4) mesocosms to test model predictions; 5) conservation assessment (review), to evaluate impacts of mitigation strategies and climate change. The student will be supervised by experts: Montagnes (grazer biology, experimental design), Warren (grazer identification and characterization), Bass (aquatic diseases); Fenton (parasite biology, modelling); Garner (host biology, conservation).