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Recent Submissions

ItemEmbargo
Measuring engagement with shark research in science, news and social media, and policy: A bibliometric analysis
(Elsevier, 2024-09-13) Toupin, Rémi; Moharana, Tamanna; Curry, Blake; Gracey, Catherine; Richards, Naomi; MacDonald, Bertrum H.; Mongeon, Philippe
Shark conservation is an urgent and complex biodiversity matter. While research on sharks is an important output of the knowledge production processes that could inform conservation policy and management decisions, whether all relevant knowledge is reaching the public and policy-makers has been questioned. Concerns have been expressed that attention given to research is skewed towards specific and often more sensationalist topics that do not provide an accurate picture of the shark-related issues and of possible solutions to decision-makers and the general public. This study thus analysed Web of Science publications related to sharks to determine the degree of visibility different areas of shark-related research received in science, social media, news media, and policy documents. Highly concentrated distributions of citations, and mentions in social media, news media, or policy documents were found, but little relationship exists between the visibility that individual publications or research areas receive in the different communication spheres. These findings show the diversity of shark-related research and its audiences and suggest a need for research evaluation to acknowledge that research impact can take many forms. In addition, developing outreach strategies is needed to ensure that relevant research is adequately disseminated to the public and policy-makers. This study can help researchers, resource managers, and other stakeholders better understand the distribution of information that could be mobilized into policies and practices for shark conservation.
ItemEmbargo
Exploring molecular mechanisms influencing rapid adaptation and development in spring and fall Atlantic Herring (Clupea harengus)
(2025-01-30) Kho, James; Yes; Doctor of Philosophy; Department of Biology; Received; Dr. Anti Vasememägi; Not Applicable; Dr. Ian Bradbury; Dr. Paul Bentzen; Dr. Daniel Ruzzante
Adaptation is a key evolutionary process by which organisms develop increased fitness in response to a change in their habitat. In marine fishes, understanding adaptation is critical for predicting how species respond to changing ocean conditions, providing insights into evolutionary biology and informing management decisions. My thesis focuses on Atlantic Herring (Clupea harengus L.), a species of immense ecological and economic importance, to explore the mechanisms and implications of adaptation in early life stages through genetic, epigenetic, and transcriptomic analyses. I first employed a suite of microsatellite markers to explore connectivity in herring through kinship structure in Gulf of St. Lawrence Spring herring and found half-sibs and potential full-sibs in a single juvenile aggregation. This is potential evidence for kinship recognition and larval retention in a herring spawning aggregation at least six months after hatching, shedding light on the genetic structure and relationship within an aggregation. I then designed a rearing experiment to assess how temperature (11°C and 13°C) and photoperiod (6 and 12 hours daylight) influence the epigenetic and transcriptomic patterns throughout larval development. In addition to high levels of global methylation levels across all samples, a decline in global methylation level was observed with increased developmental stages and was more pronounced in the 13°C treatment. Differentially methylated sites were found primarily in exon and promoter regions of genes linked to metabolism and development. These results suggest DNA methylation is an important mechanism in herring larval development and a key component to early-stage responses to environmental stressors. Alongside the epigenetic results, I found significant differential gene expression in both environmental treatments across all developmental stages but the effects on genes were stage specific. Genes associated with eye structure constituents were upregulated in longer photoperiod treatments, and immune response associated genes were upregulated in higher temperature treatments. The transcriptomic results provide novel findings into molecular mechanisms underlying herring larval development and early life-stage response to environmental stressors. This research contributes to our understanding of how populations can rapidly adjust to changing environments and highlights the complex interplay between genetics, epigenetics, and gene expression in shaping the evolutionary trajectories of natural populations.
ItemOpen Access
Marsh-estuarine benthic foraminiferal distributions and Holocene sea-level reconstructions along the South Carolina coastline.
(Dalhousie University, 1996) Collins, Eric Stephen.; Ph.D.; Department of Earth and Environmental Sciences; N/A; N/A; N/A
ItemOpen Access
Using EEG to Endophenotype Schizophrenia
(2025-01-22) Anderson, T-Jay; No; Doctor of Philosophy; Department of Psychology and Neuroscience; Received; Dr. Michael Kiang; No; Dr. Philip Tibbo; Dr. Aaron Newman; Dr. Derek Fisher
This dissertation investigates EEG-derived endophenotypes to elucidate the neurophysiological underpinnings of schizophrenia through three interconnected studies. Study 1: Meta-Analysis of Resting State Microstate Differences in Schizophrenia The first study is a meta-analysis of EEG-derived microstates in schizophrenia. Microstates are brief, stable patterns of synchronized brain activity. This meta-analysis consolidates data from numerous studies to identify consistent alterations in microstates in individuals with schizophrenia compared to healthy controls. The findings reveal significant differences in microstate classes, particularly an increase in the duration and occurrence of microstate class C and a reduction in class D. These alterations suggest disrupted neural dynamics in schizophrenia, highlighting microstate parameters as a potential endophenotype for the disorder. Study 2: Resting-State Microstate Differences in Early Psychosis as an Endophenotype Candidate. The second study explores resting-state EEG recordings to examine intrinsic brain activity in individuals with early-phase psychosis. Resting-state conditions reveal baseline brain functions, often associated with the default mode network. The study compares these microstates between individuals with early psychosis (n = 27) and healthy controls (n = 30) to determine if aberrant neural dynamics persist in the absence of external stimuli. The results indicate that individuals with early psychosis exhibit distinct microstate patterns, suggesting fundamental disruptions in brain function that could serve as reliable biomarkers for early diagnosis and monitoring of schizophrenia. Study 3: Mismatch Negativity as an Endophenotype of Schizophrenia. The third study focuses on auditory processing, a critical domain affected in schizophrenia. Using EEG, this research study investigated event-related potentials (ERPs), particularly the mismatch negativity (MMN) component, which reflects automatic auditory change detection. The study found no group differences. However, MMN measures were associated with clinical symptoms. General Conclusion: The collective findings of these studies advance our understanding of the neurophysiological abnormalities in schizophrenia. By identifying microstate alterations, this research provides evidence for EEG-derived markers as potential endophenotypes. These biomarkers offer promising avenues for early diagnosis, targeted interventions, and monitoring treatment efficacy, ultimately contributing to improved outcomes for individuals with schizophrenia.
ItemOpen Access
In Memoriam: Robert Sandeski
(Dalhousie University, 2025)
ItemOpen Access
Numerical Study of Interactions between surface waves, currents and hydrography in extreme weather conditions
(2025-01-15) Hughes, Colin; Yes; Doctor of Philosophy; Department of Oceanography; Not Applicable; Oliver Fringer; Yes; Ian Folkins; Michael Dowd; Jinyu Sheng; William Perrie
Surface gravity waves significantly affect air-sea interactions, turbulent vertical mixing, ocean currents and hydrography in the upper ocean, particularly during extreme weather events such as hurricanes and winter storms. Currents in the upper ocean also influence surface waves via the Doppler shift, relative wind effect, refraction and advection. This thesis examines the impact of wave breaking (WB), Langmuir turbulence (LT) and conservative wave effects on the upper ocean dynamics and effects of currents on surface waves during hurricane conditions using a coupled circulation-wave model. The wave-current interactions (WCIs) are investigated numerically in two cases using (a) idealized hurricanes moving at three translational speeds and (b) Hurricane Arthur (2014) over the northwest Atlantic Ocean. Model results in the fully coupled run are examined in comparison with results in other runs in which wave effects are selectively disabled to quantify main physical processes of WCIs, with a special focus on wave-induced changes to the upper ocean turbulent kinetic energy (TKE), thermal structure and currents. For the case of idealized hurricanes, analyses of model results reveal that LT has a larger impact on upper ocean currents, temperature and TKE, compared to the other considered processes. The combined wave effects reduce the surface currents in the front two quadrants of the hurricane and enhance the cold wake and near-surface cooling, predominantly to the right of the storm track. For the case of Hurricane Arthur, both the LT and WB driven acceleration are found to be important to storm-induced changes in the upper ocean temperature and circulation. By contrast, the WB induced surface flux of TKE has a limited effect on the temperature, salinity and currents in the surface layer. Over pathways of the Gulf Stream, the large WCIs reduce the significant wave heights (SWHs) of surface waves during Hurricane Arthur, with the biggest differences occurring to the right of the storm track. SWHs on the left hand side of the storm are limited by the shorter fetch, shallower water depths and coastline.