Currently, my research aims to understand how freshwater fishes will adapt to changing thermal regimes and how this will impact population productivity, species interactions and changes in species distributions.
In the past, my research focussed of the use of new methods for informing management and conservation decisions in marine and freshwater species.
Using genomic approaches to investigate the genetic basis for the recent divergence of stream- and beach-spawning kokanee salmon (Oncorhynchus nerka) and the potential for a genetics-based management approach.
At UBC (Okanagan campus), I worked to resolve the genetic basis of the divergence of stream- and beach-spawning kokanee salmon with Dr. Michael Russello and Paul Askey for two reasons. First, to infer the role of natural selection in driving contemporary evolution, a popular perception but one that lacked strong empirical evidence. Second, to identify molecular markers for conducting genetic stock assessments of as these ecotypes are very difficult to quantify on spawning grounds (beaches are slope to depths that which visibility is poor and openness allows fish to come and go), lack diagnostic morphological characters and lack sufficient differentiation at neutral loci. Kokanee have declined substantively in Okanagan Lake and under the Okanagan Lake Action Plan managers were seeking a way to improve estimation methods. We sampled several ecotype pairs from lakes in interior BC and screened hundreds of EST-linked microsatellite markers to detect regions of the genome exhibiting parallel patterns of exceptional levels of genetic differentiation among pairs. There was no evidence for strong parallel patterns in genetic divergence among ecotype pairs suggesting that there may not be a common genetic mechanism underlying the evolution of the shore-spawning ecotype. However, some markers demonstrated high accuracy and power in GSI analyses for certain lakes. We calculated an expansion factor to be integrated in the visual enumeration method for beach-spawners by genotyping trawl samples to estimate in-lake ecotype proportions and obtaining an estimate of stream-spawner abundance from a fish fence. Beach-spawners were determined to be significantly underestimated by visual counts in the past (suggesting that conservation efforts should be more focused on stream-spawners and their habitat). Furthermore, this expansion factor can be applied to any population of beach-spawners where they occur.
Using Quantitative Fatty Acid Signature Analysis (QFASA) for diet determination in large migratory birds, Laysan and Black-footed Albatross
As an undergrad, my undergrad honours project was conducted under the supervision of Sue Budges, a key member of the Sara Iverson lab when the QFASA method was first developed. We were interested in applying this method to albatross for two reasons. First, the albatross retain and store stomach oil in the proventriculus to provide offspring with energy-rich food following long foraging trips and undergoe minimal biomodification. This made the albatross ideal candidates for applying this newly developed method. Second, Laysan (Phoebastria immutabilis) and black-footed albatross (Phoebastria nigripes) are designated as vulnerable and endangered species by the World Conservation Union (IUCN), respectively, and continue to decline. Black-footed albatross were suspected to have greater susceptibility to both anthropogenic threats due to differences in diet and foraging distributions as assessed by isotope and stomach content analyses (methods known to be imprecise and biased). Fatty Acid (FA) signatures were generated for prey species and stomach oil samples using thin layer chromatography (TLC) and gas chromatography (GC) to extract fatty acids (FA) from isolated triacylglycerols (TAG). QFASA analyses showed no significant dietary differences between Laysan and Black-footed albatross suggesting this may not be the cause for distinct differences in toxin accumulation and susceptibility to fisheries. Also, results indicated that mesopelagic fishes are underestimated by conventional diet estimation methods in favour of cephalopods with digestion-resistant hard parts.