Postdoctoral Research

in comparative cardiovascular physiology. 🐟

Full CV

Selected Publications

Aqueous crude oil spills expose fish to varying concentrations of dissolved polycyclic aromatic hydrocarbons (PAHs), which can have lethal and sublethal effects. The heart is particularly vulnerable in early life stages, as PAH toxicity causes developmental cardiac abnormalities and impaired cardiovascular function. However, cardiac responses of juvenile and adult fish to acute oil exposure remain poorly understood. We sought to assess cardiac function in a pelagic fish species, the cobia (Rachycentron canadum), following acute (24 h) exposure to two ecologically relevant levels of dissolved PAHs. Cardiac power output (CPO) was used to quantify cardiovascular performance using an in situ heart preparation. Cardiovascular performance was varied using multiple concentrations of the β-adrenoceptor agonist isoproterenol (ISO) and by varying afterload pressures. Oil exposure adversely affected CPO with control fish achieving maximum CPO’s (4 mW g-1 Mv) greater than that of oil-exposed fish (1 mW g-1 Mv) at ISO concentrations of 1 × 10-6 M. However, the highest concentration of ISO (1 × 10-5 M) rescued cardiac function. This indicates an interactive effect between oil-exposure and β-adrenergic stimulation and suggests if animals achieve very large increases in β-adrenergic stimulation it could play a compensatory role that may mitigate some adverse effects of oil-exposure in vivo.
Environ. Sci. Technol., 2017, 51 (24), pp 14390–14396, 2017.

Pacific hagfish, Eptatretus stoutii, can recover from 36 h of anoxia at 10°C. Such anoxia tolerance demands the mobilization of anaerobic fuels and the removal of metabolic wastes–processes that require a functional heart. The purpose of this study was to measure the metabolic response of the excised, cannulated hagfish heart to anoxia using direct calorimetry. These experiments were coupled with measurements of cardiac pH and metabolite concentrations, at multiple time points, to monitor acid-base balance and anaerobic ATP production.
J Exp Biol., 2015.

In order for an animal to survive, the heart beat must go on in all environmental conditions, or at least restart its beat. This review is about maintaining a rhythmic heartbeat under the extreme conditions of anoxia (or very severe hypoxia) and high temperatures. It starts by considering the primitive versions of the protein channels that are responsible for initiating the heartbeat, HCN channels, divulging recent findings from the ancestral craniate, the Pacific hagfish (Eptatretus stoutii). It then explores how a heartbeat can maintain a rhythm, albeit slower, for hours without any oxygen, and sometimes without autonomic innervation. It closes with a discussion of recent work on fishes, where the cardiac rhythm can become arrhythmic when a fish experiences extreme heat.
Comp Biochem Physiol A Mol Integr Physiol., 2015.

This study was undertaken to provide a comprehensive set of data relevant to disclosing the physiological effects and possible oxygen transport limitations in the Chinook salmon ( Oncorhynchus tshaw-ytscha ) during an acute temperature change. Fish were instrumented with a blood flow probe around the ventral aorta and catheters in the dorsal aorta and sinus venosus.
Am J Physiol Regul Integr Comp Physiol 295: R1631–R1639, 2008.

Recent Publications

More Publications

. Oil Exposure Impairs In Situ Cardiac Function in Response to β-Adrenergic Stimulation in Cobia (Rachycentron canadum). Environ. Sci. Technol., 2017, 51 (24), pp 14390–14396, 2017.

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. Cardio-respiratory function during exercise in the cobia, Rachycentron canadum: The impact of crude oil exposure.. Comp Biochem Physiol C Toxicol Pharmacol. 201:58-65, 2017.

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. Determinants of coronary blood flow in sandbar sharks, Carcharhinus plumbeus. J Comp Physiol B., 2017.

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. Effects of crude oil on in situ cardiac function in young adult mahi-mahi (Coryphaena hippurus). Aquatic Toxicology Volume 180, Pages 274-281, 2016.

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. Introducing a novel mechanism to control heart rate in the ancestral Pacific hagfish. J Exp Biol., 2016.

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. Morphological arrangement of the coronary vasculature in a shark (Squalus sucklei) and a teleost (Oncorhynchus mykiss). Journal of Morphology, 277: 896–905, 2016.

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. Characterizing the metabolic capacity of the anoxic hagfish heart.. J Exp Biol., 2015.

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. The beat goes on: Cardiac pacemaking in extreme conditions.. Comp Biochem Physiol A Mol Integr Physiol., 2015.

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. A Perspective on the Evolution of the Coronary Circulation in Fishes and the Transition to Terrestrial Life. Ontogeny and Phylogeny of the Vertebrate Heart pp 75-102, 2012.

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. Anoxic survival of the Pacific hagfish (Eptatretus stoutii). J Comp Physiol B., 2011.

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Recent & Upcoming Talks

Getting to the heart of the matter: oxygen supply and demand in fish.
Apr 23, 2018 1:00 PM

Recent Posts

I appeared in the documentary movie Dispatches From the Gulph 2, narrated by actor Matt Damon, that examined the mission to study the impacts of the Deepwater Horizon oil spill.

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The Canadian Society of Zoologists, as the leading society for advancement of zoological research, is essential for fostering the development of young scientists and enthusiasm towards research in our field. As such, postdoctoral representation on the Council and CSZ meetings and events is essential for the advancement of both the field of zoology and for postdocs themselves.

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My research interests have necessitated the development of a wide array of scientific abilities, spanning across field, laboratory, surgical, biochemical, histological, and analytical techniques. I have gained valuable insight into the importance and limitations of fieldwork by conducting research on three marine research vessels and by participating in the capture of a variety of large, dangerous, and fragile fish species. These experiences taught me appropriate fish handling, holding, and transportation techniques along with how sample, tag, and release fish.

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My primary over-arching interest is understanding how marine organisms that inhabit heterogeneous environments are able to physiologically cope with abiotic stressors and changing environments.

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Post Doctoral Fellow, University of Pennsylvania, Perelmen School of Medicine, University of Pennsylvania (2017 – present).

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Projects

Cardiac Oxygen Supply and the Morphology of Shark Hearts

Providing novel insights into the evolution of the coronary artery and cardiac oxygen delivery in vertebrates. sharks are ideal model species as they are the most ancient vertebrates to possess a coronary artery.

Cardiac function following oil exposure in pelagic fish

During my postdoc as part of the RECOVER consortium, funded through GOMRI, I have investigated whether phenotypic plasticity allows species to overcome anthropogenic sources of environmental pollution in the form of polycyclic aromatic hydrocarbons (PAH’s), the toxic components of oil.

Cardiovascular function of hagfish in anoxia (no oxygen) environments

In this study, and in conjunction with my work on cardiovascular responses to anoxia in hagfish, I discovered a number of diverse cardiovascular and biochemical phenotypes that permitted the survival of hagfish for more than 36 hours of complete oxygen deprivation.

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