Interacting threats to Swedish salmonids: temperature, dams and an emerging disease

Infectious agents play a major role in ecosystem functioning but knowledge on their interactive effects with climate change and habitat fragmentation is currently very limited.

This project’s goal is to understand the impact of the temperature-dependent myxozoan parasite T. bryosalmonae (Tb; causing Proliferative Kidney Disease, PKD) on Swedish brown trout in relation to climate and habitat fragmentation, and to help develop conservation and management actions to combat this emerging and dangerous disease.To accomplish this, we will: i) quantify combined impacts of PKD and increasing water temperature on brown trout recruitment; ii) assess the role of dams as migration barriers on Tb spread and as catalysts for PKD; iii) apply novel environmental DNA methods to elucidate Tb infectivity, distribution, and life-cycle; iv) advise on restoration and protection measures incorporating Tb-associated risks.Results from this work will have far-reaching significance contributing to heathier fish stocks due to three main outcomes: i) the information on occurrence of the emerging parasite will be of critical importance for decision-makers on restoring the connectivity of rivers currently fragmented by dams; ii) understanding the potential spread and impact of PKD on brown trout will support blue growth and economic development; iii) by applying novel environmental DNA analysis methods, the current proposal promotes incorporation of non-invasive monitoring tools for aquatic species.