Parasitism in aquatic communities- environmental influences and multiple stressors

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In the last 25 years, amphibians have become the most imperiled class of vertebrates worldwide. The causes of such declines are diverse, including challenges from habitat loss, invasive species, climate change, and infectious disease, some or all of which might interact through complex mechanisms. My students and I will aim to understand the importance of and mechanisms behind pathogen involvement in worldwide amphibian declines, as well as explore the broader applications of this knowledge to other aquatic organisms. Growing attention has recently focused on the question of how environmental change affects host-parasite interactions. There is now recognition that parasites can exert particularly important effects on larval amphibians, such as limb malformations due to the trematode Ribeiroa ondatrae, a platyhelminth (flatworm). Recent research has demonstrated clear links between certain environmental factors, such as agricultural pesticides, and parasite infection in amphibians. This program of research and training will help to determine whether effects of agricultural pesticides are general or specific, whether these effects are more likely to occur in specific conditions, how long-lived these effects are, and if effects are host and/or parasite-specific. Such work will need to be publically translated to aid in the development of appropriate guidelines for amphibian conservation. This work will also include realistic considerations, as natural populations are often exposed to more than one stressor concurrently with potential interactive effects on hosts. Recent work has shown that parasite effects on host condition are highly context-dependent. The proposed work will focus on the influence of parasitic infection on host susceptibility to future infections, the ability of infected larval amphibians to withstand pond drying, and the effects of cyanobacterial toxins on infected amphibians. Various combinations of such stressors could be an underlying cause of observed amphibian declines, and may similarly impact other aquatic organisms.