Impacts of newly established non-indigenous green crab (Carcinus maenas) on native fauna in Placentia Bay, Newfoundland

The recent invasion of the European green crab (Carcinus maenas) populations in Placentia Bay, Newfoundland and Labrador (NL) raises great concern about potential impacts on local fisheries and native biodiversity. Green crab are highly adaptable and in both native and invaded areas, green crab are well established predators that can outcompete other similarly sized decapods. The main objectives of this thesis were to: 1) identify the native species that green crab compete with for resources; 2) determine the depths and substrate types in which these interactions likely occur; 3) assess the indirect effects of green crab on native crustaceans and their changes in behavior; 4) assess the impacts of green crab on benthic community structure; 5) compare the NL population with other Atlantic Canadian populations in terms of competitive abilities; and 6) compare morphological features of the NL population with other Atlantic Canadian populations. I found that green crab overlap in space and diet with both rock crab (Cancer irroratus) and American lobster (Homarus americanus), potentially leading to a shift in habitat. Laboratory studies on naïve juvenile lobster also suggested shifts in behavior related to green crab, in that lobster decreased foraging activity and increased shelter use in the presence of green crab. Benthic community analyses showed fewer species in mud, sand, and eelgrass sites heavily populated by green crab compared to sites without green crab, although results depended on the taxa involved and I could not eliminate environmental differences through a short term caging study. Foraging ability of green crab varied in intraspecific competition experiments, with populations from NL and Prince Edward Island dominating longer-established populations from Nova Scotia and New Brunswick. Additional studies excluded claw size as a factor driving these results and behavioral differences likely reflected differences in invasion time and population genetics. Overall, green crab in Placentia Bay appear to be altering community structure of benthic invertebrates through predation and they also appear to indirectly impact native crustaceans through competition.

The Ross's Gull (Rhodostethia rosea) in North America

The population, distribution and range of the Ross's gull in North America remain poorly understood, as does almost every aspect of its ecology and biology. It breeds at a few disparate locations in the Canadian Arctic and is an annual fall migrant in northern Alaska where tens of thousands occur in the nearshore waters of the Beaufort and Chukchi Seas, but little else is known about the distribution, habitat requirements, migratory routes and wintering areas used by this species. In order to clarify the status of the Ross's gull in North America I sought to discover new breeding sites in the Canadian High Arctic in order to characterize nesting habitat requirements, develop a predictive model with which to identify suitable nesting habitat for Ross's gulls, and refresh outdated estimates of the number of individuals migrating past Point Barrow, Alaska. Taken together, my findings provide a comprehensive account of the current status of the Ross's gull in North America.

Scope & nature of young sudden cardiac death in Newfoundland & Labrador

Introduction: Sudden cardiac death (SCD) in young people (ages 2-40) is a tragedy for families and communities alike. It has multiple causes, one of which is an underlying genetic arrhythmogenic cardiomyopathy. A study from Ontario (ON) using a 2008 cohort assessed the incidence of SCD in persons aged 2-40 years to be 2.64/100,000 person-years. We hypothesized that Newfoundland & Labrador (NL) may have a higher incidence of early SCD in ages 2-40 due to possible underlying genetic causes given the historical genetic isolation of the population and the founder mutations already identified (ex. PKP2, RYR2, TMEM43). Methods: We ascertained cases of sudden death from the comprehensive Medical Examiners’ provincial database for the years 2008 and 1997; 2008 as a direct comparison to ON, and 1997 as it represented a time when the implantable cardioverter-defibrillator was not available in NL. Each case of sudden death was individually analyzed to determine likelihood of SCD. Results: There were 119 cases in 2008 and 157 cases in 1997. The incidence of SCD for ages 2-40 in 2008 was 7.32/100,000 persons. This was significantly higher than the incidence in Ontario. The incidence of SCD was not significantly higher in 1997 than 2008. Coronary artery disease was a major cause of death in all cohorts, similar to Ontario (non-significant difference). Conclusion: In general, there was a trend of more arrhythmogenic deaths in the young and more structural cardiac deaths as age increased. This reflects the cause of SCD in the young is often genetic in nature, while older deaths are often due to coronary artery disease, a disease heavily influenced by environment. To conclude, SCD in NL occurs at a higher incidence than ON, further research is needed on the topic.