My broad research interests surround the physiological responses of organisms to stressors. As a PhD student my research aims were targeted at understanding how different aspects of behaviour and life-history stage affect stress axis function. As a postdoctoral researcher, I am now applying the molecular tools and experience I gained during my PhD to assess more applied research questions including the impacts of a management strategy (elevated carbon dioxide) for the control Bigheaded carp on resident non-target animals, and the stress status of silver carp in the Illinois River. Overall, I am interested in assessing how responses to stressors are impacted by behavior, life-history stages as well as environmental changes, and evaluating these effects at the whole-animal level as well as at the cellular and molecular level.
Significant alterations to Lake Winnipeg have resulted from the cumulative effects of eutrophication, invasive species, and commercial fisheries, the magnitude of which can vary across the watershed. As part of a study monitoring wild-caught walleye movement in Lake Winnipeg, we will be assessing regional differences in molecular indices (transcriptomic and metabolomic) across five distinct locations.
POSTDOCTORAL RESEARCH AT THE UNIVERSITY OF ILLINOIS WITH DR. CORY SUSKI
STRESS & CONDITION OF SILVER CARP IN THE ILLINOIS RIVER
Bigheaded carp were introduced into the US in the 1970’s and have since spread throughout the major river basins of the Midwestern US. Population densities of bigheaded carp have reached iconic levels in certain reaches of the Illinois River, and there is the potential for their movement beyond the Mississippi Basin into the Great Lakes via the City of Chicago and its network of drainage canals. Interestingly, despite their vast population growth and spread, the ‘leading edge’ of bigheaded carp populations in the Illinois river has advanced little over the past several years (about 70 miles from Lake Michigan). A number of environmental factors (e.g., food availability, water quality) may potentially explain why bigheaded carp have not moved beyond their current distribution, however, this is not well understood. Understanding how the physiology of bigheaded carp at their ‘leading edge’ compares to that of carp at other points in their range, may provide additional information about why these fish have not spread further. In this study we will be using RNAseq technology to assess biological processes (e.g., stress, response to toxins, etc.) that may be regulated in silver carp at different locations across their range.
IMPACTS OF ELEVATED CARBON DIOXIDE ON RESIDENT FRESHWATER SPECIES
In an effort to control the movement of invasive Bigheaded carp, non-permanent barriers provide an attractive alternative to permanent barriers that would majorly alter the waterway. The use of elevated carbon dioxide is one possible non-permanent barrier to the movement of Bigheaded carp that is being explored. It is important, however, to first understand the potential consequences of elevating carbon dioxide levels in the water for other resident organisms, such as freshwater mussels. In this work, we are examining the potential physiological impacts of elevated carbon dioxide on resident mussels. Overall, adult freshwater mussels appear to respond to both short- and long-term, as well as intermittent exposure to elevated carbon dioxide by increasing processes associated with acid-base regulation and the cellular stress response, as well as alter the biological control of shell formation (Hannan et al., 2016a,b,c; Jeffrey et al., 2017, in press). In addition, to determine the potential effects of elevated carbon dioxide coupled with other environmental stressors, we are investigating the interactive effects of elevated carbon dioxide and temperature on juvenile freshwater mussels.
PHD RESEARCH AT THE UNIVERSITY OF OTTAWA WITH DR. KATIE GILMOUR
SOCIAL STATUS MEDIATES CORTICOSTEROID AXIS FUNCTION
Social hierarchies form in groups of juvenile salmonids and we have shown that hypothalamic-pituitary-interrenal axis function is mediated by social status in rainbow trout (Jeffrey et al., 2012). In addition, socially subordinate juvenile rainbow trout are unable to mount a robust cortisol response when exposed to an additional acute stressor (Jeffrey et al., 2014).
EFFECTS OF MATERNAL SOCIAL STRESS
Like juvenile salmonids, adult zebrafish also form social hierarchies. This allowed us to assess how maternal social status affects the offspring of female zebrafish of different social status. Specifically, we investigated the impacts of maternal social status on development of the stress axis in young zebrafish offspring as well as their responses to a stressor once the stress axis is fully established (Jeffrey, 2014).
MEDIATION OF CORTICOSTEROID AXIS FUNCTION DURING THE PARENTAL CARE PERIOD
Male smallmouth bass provide sole parental care to offspring until they reach independence. During this time, males attenuate their cortisol response to acute stress, a response that seems to be mediated by modulation of key genes in the hypothalamic-pituitary-interrenal axis (Jeffrey et al., 2014). This work was done in collaboration with Dr. Steve Cooke at Carleton University.