Grant: Discovery Grants Program - Individual

The focus of this research is a series of integrative investigations in how multiple factors affect responses of fishes to novel or alternative environments. The first objective explores how characteristics of the mother (i.e. maternal forces) may have knock-on effects that shape the expression of alternative migratory tactics (residency versus ocean migration) within populations of salmonid fishes. Females that migrate to sea access different resources than those that do not, which may affect both the amount and form of resources (e.g., lipids and omega-3 fatty acids) allocated to their offspring. These differences in turn may affect the competitive ability and survival of their offspring, and influence the expression of the alternative migratory life histories. We will test this using the Atlantic salmon in Newfoundland where these two migratory forms coexist, combining field studies with controlled lab analyses of egg and offspring quality to explore behavioural differences and survival consequences. In the second objective, we investigate the consequences of a human-mediated introduction and spread of an invasive species, the brown trout in Newfoundland, to understand its response to the novel environment in terms of behaviour, diet and body shape along two separate colonisation routes. The ecological effects of the invasion will also be examined, as impacts can occur on a wide range of native organisms through establishment of novel interactions that modify multiple components of the recipient ecosystems. To this end, we will quantify impacts on stream invertebrates, algal growth, microbial activity and fishes, particularly the closely related Atlantic salmon, by comparing streams invaded by brown trout to those that have not been invaded. It is anticipated that the brown trout invasion will lead to character displacement in Atlantic salmon, affecting their behaviour, diet and body shape. Moreover, we will quantify the impact (rate) of hybridization between trout and salmon, as this may be a significant threat and could be most prevalent at the invasion front where brown trout densities will be low. The final objective explores the potential vulnerability of ocean-migratory Arctic char in Labrador to climate change given the mounting evidence that the southernmost populations may be at risk of marked depletion in the coming decades. As marine habitat use is critical for these fish, we will characterize the marine movement, diet and nutritional status across the latitudinal gradient of Labrador in partnership with local Inuit communities. The overarching goal is to increase predictive understanding of the likely effects of future environmental change on trophic status, growth, and dietary preferences of Arctic char across the diverse marine ecosystems of Labrador.