Anthony P. Farrell's research while affiliated with University of British Columbia and other places
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Publications (328)
Climatic warming elevates mortality for many salmonid populations during their physically challenging up-river spawning migrations, yet, the mechanisms underlying the increased mortality remain elusive. One hypothesis posits that a cardiac oxygen insufficiency impairs the heart’s capacity to pump sufficient oxygen to body tissues to sustain up-rive...
Natural selection has produced many vertebrate 'solutions' for the cardiac life-support system, especially among the approximately 30,000 species of fishes. For example, across species, fish have the greatest range for central arterial blood pressure and relative ventricular mass of any vertebrate group. This enormous cardiac diversity is excellent...
Phenotypic plasticity manifested after acclimatization is a very important source of biological variability among fish species. We hypothesized that hypoxic acclimation, besides potentially generating a temporary hypoxic respiratory phenotype, would also manifest as a continued benefit after re-acclimation to normoxia. Hence, we holistically charac...
Fitness of fish is assumed to be influenced by locomotion performance, but empirical evidence linking swimming capacity to survival in nature remains sparse. Poor triploid (3N) fish aerobic swimming performance in conjunction with production of sibling diploid (2N) and 3N populations of genetically identical origin to minimize variability among com...
Fish blood has three components: red blood cells (RBCs), white blood cells (WBCs) and plasma. Their ratio is typically 20–40% RBCs, 0.5–2.0% WBCs and 60–80% plasma. However, fish phylogeny influences the composition (in some species RBCs are absent) and the RBC and WBC numbers can vary dynamically. Short term temporal changes in hematocrit typicall...
The earliest observations on the secondary circulation date back more than 100 years. Since the secondary circulation was an unknown concept, vessels of the secondary circulation were considered lymphatic vessels until the 1980s, when the secondary circulation was recognized as a separate and parallel system of vessels derived from the arterial ves...
This article reviews the anatomy of the fish heart and its coronary circulation in relation to their functions. The shape, size and anatomy of the cardiac chambers vary greatly among species but, in general, the venous blood enters to sinus venosus from ductus Cuvier. The sino-atrial canal connects the sinus venosus to the atrium, which pumps blood...
Millions of liters of diluted bitumen (dilbit), a crude oil product from Canada's oil sands region, is transported through critical Pacific salmon habitat each day. While the toxicity of the water-soluble fraction of dilbit (WSFd) to early life-stages of salmon is known, quantitative data on life-stage differences in sensitivity to WSFd is missing....
For many freshwater and diadromous fishes, dams create a significant conservation challenge by fragmenting migratory routes, modifying habitats and altering patterns of water movement. Despite advances in fish passage strategies and infrastructure, passage can still be delayed or prevented. Fish can experience a variety of physiological issues as a...
It is widely regarded that we have entered a new epoch distinct from the Holocene which is defined by the dominance of humans—termed the “Anthropocene.” Indeed, for centuries humans have altered aquatic ecosystems by degrading habitats, altering ecosystem structure, and impairing ecosystem function. In the Anthropocene, aquatic ecosystems and their...
Migratory fishes commonly encounter large and rapid thermal variation, which has the potential to disrupt essential physiological functions. Thus, we acclimated wild, migratory Arctic char to 13°C (∼7°C above a summer average) for an ecologically relevant period (3 days) and measured maximum heart rate (ƒHmax) during acute warming to determine thei...
With regional hypoxic episodes in the world’s oceans becoming more severe and more frequent, a valuable management need will be a screening protocol to characterize the full diversity of hypoxic robustness among fishes (defined here as their tolerance and performance). Yet, high-throughput screening protocols to deal with the almost 33,000 fish spe...
Two hypotheses were tested concerning the consequences to adult sockeye salmon (Oncorhynchus nerka) of escape from commonly used fishing gear (gillnet, seine net and tangle net). First, by experimentally exposing 214 fish to three commonly used fishing gear types (gillnets, tangle nets, or seine nets) and releasing to complete migration after PIT-t...
One of the physiological mechanisms that can limit a fish's ability to face hypoxia or elevated temperature, is maximal cardiac performance. Yet, few studies have measured how cardiac electrical activity and associated calcium cycling proteins change with acclimation to those environmental stressors. To examine this, we acclimated European sea bass...
The hypoxic constraint on peak oxygen uptake (ṀO2peak) was characterized in rainbow trout over a range of ambient oxygen tensions with different testing protocols and statistical models. The best-fit model was selected using both statistical criteria (R2 & AIC) and the model's prediction of three anchor points for hypoxic performance: critical PO2...
Warm acclimation in fish is often characterized by an increase in heat tolerance and a reduction in physiological rates to improve the scope to respond to additional challenges including further warming. The speed of these responses can determine their effectiveness. However, acclimation rates vary across levels of biological organization and are p...
This meta-study uses phylogenetic scaling models across more than 30 species, spanning five orders of magnitude in body mass, to show that cardiac capillary numerical density and mitochondrial volume density decrease with body mass raised to the -0.07 ± 0.03 and -0.04 ± 0.01 exponents, respectively. Thus, while an average 10 g mammal has a cardiac...
Thermal acclimation, a compensatory physiological response, is central to species survival especially during the current era of global warming. By providing the most comprehensive assessment to date for the cardiorespiratory phenotype of rainbow trout (Oncorhynchus mykiss) at six acclimation temperatures from 15 • C to 25 • C, we tested the hypothe...
The vertebrate circulatory system consists of a central pump (the heart), a system of tubes (the vascular and lymphatic vessels), fluid (blood and lymph) and a control system (neural, endocrine, paracrine and autocrine factors) that serves to transport gases, nutrients and other substances around the body.
Key Concepts
• Gases, nutrients, immune...
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handli...
Background
Viruses can impose energetic demands on organisms they infect, in part by hosts mounting resistance. Recognizing that oxygen uptake reliably indicates steady-state energy consumption in all vertebrates, we comprehensively evaluated oxygen uptake and select transcriptomic messaging in sockeye salmon challenged with either a virulent rhabd...
The utility of measuring whole-animal performance to frame the metabolic response to environmental hypoxia is well established. Progressively reducing ambient oxygen (O2) will initially limit maximum metabolic rate as a result of a hypoxemic state and ultimately lead to a time-limited, tolerance state supported by substrate-level phosphorylation wh...
Warming in the region of the Western Antarctic Peninsula is occurring at an unprecedented rate, which may threaten the survival of Antarctic notothenioid fishes. Herein, we review studies characterizing thermal tolerance and cardiac performance in notothenioids – a group that includes both red-blooded species and the white-blooded, haemoglobinless...
Incorporating host-pathogen(s)-environment axes into management and conservation planning is critical to preserving species in a warming climate. However, the role pathogens play in host stress resilience remains largely unexplored in wild animal populations. We experimentally characterized how independent and cumulative stressors (fisheries handli...
In recent decades, the relative proportion of female sockeye salmon (Oncorhynchus nerka) on spawning grounds of several British Columbia populations has declined. Coincident with the decline has been large changes to oceanic, estuarine and river migration environments. Over the past 30 years, numerous telemetry tracking and laboratory studies have...
We tested in six fish species [Pacific lamprey (Lampetra richardsoni), Pacific spiny dogfish (Squalus suckleyi), Asian swamp eel (Monopterus albus), white sturgeon (Acipenser transmontanus), zebrafish (Danio rerio), and starry flounder (Platichthys stellatus)] the hypothesis that elevated extracellular [HCO3⁻] protects spontaneous heart rate and ca...
Increasing heart rate (ƒH) is a central, if not primary mechanism used by fishes to support their elevated tissue oxygen consumption during acute warming. Thermal acclimation can adjust this acute response to improve cardiac performance and heat tolerance under the prevailing temperatures. We predict that such acclimation will be particularly impor...
Our analysis shows good intentions in the selection of valid and precise oxygen uptake (ṀO2) measurements by retaining only slopes of declining dissolved oxygen level in a respirometer that have very high values of the coefficient of determination, r², are not always successful at excluding nonlinear slopes. Much worse, by potentially removing line...
Pacific salmon undertake iconic homeward migrations where they move from ocean feeding grounds to coastal rivers where they return to natal spawning sites. However, this migration is physiologically challenging as fish have to navigate past predators, nets, hooks, and dams while dealing with variable flows, warm water temperatures, and pathogens. T...
Intraspecific variation in key traits such as tolerance of warming can have profound effects on ecological and evolutionary processes, notably responses to climate change. We review the empirical evidence for three primary elements of intraspecific variation in tolerance of warming in fishes. The first is purely mechanistic, that tolerance varies a...
We examined cardiac pacemaker rate resetting in rainbow trout following a reciprocal temperature transfer. In the original experiment, performed in winter, 4°C-acclimated fish transferred to 12°C reset intrinsic heart rate after just 1 h (from 56.8±1.2 to 50.8±1.5 bpm); 12°C-acclimated fish transferred to 4°C reset intrinsic heart rate after 8 h (f...
Despite immense concern over amplified warming in the Arctic, physiological research to address related conservation issues for valuable cold-adapted fish, such as the Arctic char (Salvelinus alpinus), is lacking. This crucial knowledge gap is largely attributable to the practical and logistical challenges of conducting sensitive physiological inve...
Canada's oil sands industry continues to expand and the volume of diluted bitumen (dilbit) transported across North America is increasing, adding to spill risk and environmental contamination. Dilbit exposure is known to cause adverse effects in fish, but linking molecular and cellular changes with ecologically-relevant individual performance metri...
Petrogenic chemicals are common and widespread contaminants in the aquatic environment. In Canada, increased extraction of bitumen from the oil sands and transport of the major crude oil export product, diluted bitumen (dilbit), amplifies the risk of a spill and contamination of Canadian waterways. Fish exposed to sublethal concentrations of crude...
Both laboratory and field respirometry are rapidly growing techniques to determine animal performance thresholds. However, replicating protocols to estimate maximum metabolic rate (MMR) between species, populations, and individuals can be difficult, especially in the field. We therefore evaluated seven different exercise treatments-four laboratory...
The cardiovascular system is critical for delivering O2 to tissues. Here we examine the cardiovascular responses to progressive hypoxia in four high-altitude Andean duck species compared to four related low-altitude populations in North America, tested at their native altitude. Ducks were exposed to stepwise decreases in inspired partial pressure o...
Synopsis
Researchers have surmised that the ability to obtain dominance during reproduction is related to an individual’s ability to better sequester the energy required for reproductive behaviors and develop secondary sexual characteristics, presumably through enhanced physiological performance. However, studies testing this idea are limited. Usin...
This study hypothesized that oxygen uptake (ṀO 2) measured with a novel protocol of chasing rainbow trout Oncorhynchus mykiss to exhaustion inside a static respirometer while simultaneously monitoring ṀO 2 (ṀO 2chase) would generate the same and repeatable peak value as when peak active ṀO 2 (ṀO 2active) is measured in a critical swimming speed pro...
[This corrects the article DOI: 10.3389/fphys.2019.00114.].
Common killifish Fundulus heteroclitus were acclimated to ecologically relevant temperatures (5, 15 and 33oC) and their maximum heart rate (fHmax) was measured at each acclimation temperature during an acute warming protocol. Acclimation to 33oC increased peak fHmax by up to 32% and allowed the heart to beat rhythmically at a temperature 10oC highe...
Here, we show that heart rate in zebrafish Danio rerio is dependent upon two pacemaking mechanisms and it possesses a limited ability to reset the cardiac pacemaker with temperature acclimation. Electrocardiogram recordings, taken from individual, anaesthetised zebrafish that had been acclimated to 18, 23 or 28oC were used to follow the response of...
Antarctic notothenioids, some of which lack myoglobin (Mb) and/or haemoglobin (Hb), are considered extremely stenothermal, which raises conservation concerns since Polar regions are warming at unprecedented rates. Without reliable estimates of maximum cardiac output ($\dot{Q}$), it is impossible to assess their physiological scope in response to wa...
Multiple stressors are commonly encountered by wild animals, but their cumulative effects are poorly understood, especially regarding infection development. We conducted a holding study with repeated gill and blood sampling to characterize the effects of cumulative stressors on infection development in adult coho salmon. Treatments included chronic...
An organism’s ability to respond effectively to environmental change is critical to their survival. Yet, life stage and overall condition can dictate tolerance thresholds to heightened environmental stressors, such that stress may not be equally felt across individuals and at all times. Also, the transcriptional responses induced by environmental c...
As fish approach fatigue at high water velocities in a critical swimming speed (Ucrit) test, their swimming mode and oxygen cascade typically move to an unsteady state because they adopt an unsteady, burst-and- glide swimming mode despite a constant, imposed workload. However, conventional rate of oxygen uptake (M_ O2) sampling intervals (5–20min)...
Acute warming in fish increases heart rate (fH) and cardiac output to peak values, after which performance plateaus or declines and arrhythmia may occur. This cardiac response can place a convective limitation on systemic oxygen delivery at high temperatures. To test the hypothesis that autonomic cardiac regulation protects cardiac performance in r...
Scaling of the heart across development can reveal the degree to which variation in cardiac morphology depends on body mass. In this study, we assessed the scaling of heart mass, left and right ventricular masses, and ventricular mass ratio, as a function of eviscerated body mass across fetal and postnatal development in Horro sheep Ovis aries (~50...
The recent ubiquitous detection of PRV among salmonids has sparked international concern about the cardiorespiratory performance of infected wild and farmed salmon. Piscine orthoreovirus (PRV) has been shown to create substantial viremia in salmon by targeting erythrocytes for principle replication. In some instances, infections develop into heart...
The Southern Ocean has experienced stable, cold temperatures for over 10 million years, yet particular regions are currently undergoing rapid warming. To investigate the impacts of warming on cardiovascular oxygen transport, we compared the cardio-respiratory performance in an Antarctic notothenioid (Notothenia coriiceps) that was maintained at 0 o...
Icefishes characteristically lack the oxygen-binding protein haemoglobin and therefore are especially reliant on cardiovascular regulation to augment oxygen transport when oxygen demand increases, such as during activity and warming. Using both in vivo and in vitro experiments, we evaluated the roles for adrenaline and adenosine, two well-establish...
Early marine survival of juvenile salmon is intimately associated with their physiological condition during ocean entry and especially smoltification. Smoltification is a developmental parr-smolt transformation allowing salmon to acquire the trait of seawater tolerance in preparation for marine living. Traditionally, this developmental process has...
Chemical immobilization is necessary for the physiological study of large wild animals. However, the immobilizing drugs can adversely affect the cardiovascular and respiratory systems, yielding data that do not accurately represent the normal, resting state. We hypothesise that these adverse effects can be ameliorated by reversing the immobilizing...
Equatorial fishes, and the critically important fisheries based on them, are thought to be at-risk from climate warming because the fishes have evolved in a relatively aseasonal environment and possess narrow thermal tolerance windows that are close to upper thermal limits. We assessed survival, growth, aerobic performance and critical thermal maxi...
We show that cardiac sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA) activity differs considerably among sockeye salmon (Oncorhynchus nerka) populations. Variability in SERCA activity was significantly correlated with elevation gain and temperature during migration, as well as maximum cardiac stroke volume. Furthermore, because SERCA activity was...
In all vertebrates studied to date, CO2 excretion depends on the enzyme carbonic anhydrase (CA) that catalyses the rapid conversion of HCO3- to CO2 at the gas-exchange organs. The largest pool of CA is present within red blood cells (RBC) and, in some vertebrates, plasma-accessible CA (paCA) isoforms participate in CO2 excretion. However, teleost f...
There is a paucity of information on the physiological changes that occur over the course of salmon early marine migration. Here we aim to provide insight on juvenile Coho salmon (Oncorhynchus kisutch) physiology using the changes in gene expression (cGRASP 44K microarray) of four tissues (brain, gill, muscle, and liver) across the parr to smolt tr...
Consequences of exposure to polyaromatic hydrocarbons (PAH), toxic components of crude oil, on fish has been widely documented due to their ecological and economical importance. However, although forming a valuable and consistent body of knowledge, use of these data in spill response is limited. Objective of the present study was thus to facilitate...
• Climate change poses a challenge to wild fishes, yet little is known about the behavioural use and metabolic consequences of thermally heterogeneous water encountered by wild salmon during their energetically demanding upstream spawning migration.
• Temperature, body size and activity levels were modelled to predict energy depletion of salmon dur...
We tested the hypothesis that Blackfin icefish (Chaenocephalus aceratus), one of the six species in the family Channichthyidae (the icefishes) that do not express haemoglobin and myoglobin, lack regulatory cardiovascular flexibility during acute warming and activity. The experimental protocols were designed to optimize the surgical protocol and min...
Temperature is a master environmental factor that limits the geographical distribution of species, especially in ectotherms. To address challenges in biodiversity conservation under ongoing climate change, it is essential to characterize relevant functional limitations and adaptive genomic content at population and species levels. Here, we present...
Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contributes to thermal tolerance. Here we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compare...
The early life stages of Pacific salmon are at risk of environmental exposure to diluted bitumen (dilbit) as Canada's oil sands industry continues to expand. The toxicity and latent effects of dilbit exposure were assessed in sockeye salmon (Oncorhynchus nerka) exposed to water-soluble fractions of dilbit (WSFd) from fertilization to the swim-up st...
The hearts of smaller mammals tend to operate at higher mass-specific mechanical work rates than those of larger mammals. The ultrastructural characteristics of the heart that allow for such variation in work rate still is largely unknown. We have used perfusion-fixation, transmission electron microscopy and stereology to assess the morphology and...