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Lesku JA, Libourel PA, Kelly ML, Hemmi JM, Kerr CC, Collin SP, Radford CA. An electrophysiological correlate of sleep in a shark. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2024. [PMID: 38957102 DOI: 10.1002/jez.2846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 06/11/2024] [Accepted: 06/13/2024] [Indexed: 07/04/2024]
Abstract
Sleep is a prominent physiological state observed across the animal kingdom. Yet, for some animals, our ability to identify sleep can be masked by behaviors otherwise associated with being awake, such as for some sharks that must swim continuously to push oxygenated seawater over their gills to breathe. We know that sleep in buccal pumping sharks with clear rest/activity cycles, such as draughtsboard sharks (Cephaloscyllium isabellum, Bonnaterre, 1788), manifests as a behavioral shutdown, postural relaxation, reduced responsiveness, and a lowered metabolic rate. However, these features of sleep do not lend themselves well to animals that swim nonstop. In addition to video and accelerometry recordings, we tried to explore the electrophysiological correlates of sleep in draughtsboard sharks using electroencephalography (EEG), electromyography, and electrooculography, while monitoring brain temperature. The seven channels of EEG activity had a surprising level of (apparent) instability when animals were swimming, but also when sleeping. The amount of stable EEG signals was too low for replication within- and across individuals. Eye movements were not measurable, owing to instability of the reference electrode. Based on an established behavioral characterization of sleep in draughtsboard sharks, we offer the original finding that muscle tone was strongest during active wakefulness, lower in quietly awake sharks, and lowest in sleeping sharks. We also offer several critical suggestions on how to improve techniques for characterizing sleep electrophysiology in future studies on elasmobranchs, particularly for those that swim continuously. Ultimately, these approaches will provide important insights into the evolutionary confluence of behaviors typically associated with wakefulness and sleep.
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Affiliation(s)
- John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
| | - Paul-Antoine Libourel
- Center for Functional and Evolutionary Ecology, MAD Team, Montpellier, France
- Neuroscience Research Center of Lyon, Sleep Team, Bron, France
| | - Michael L Kelly
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
- Australian Centre for Disease Preparedness, Commonwealth Scientific and Industrial Research Organisation, Geelong, Victoria, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Caroline C Kerr
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
| | - Shaun P Collin
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
- Oceans Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Craig A Radford
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
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2
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Norman H, Munson A, Cortese D, Koeck B, Killen SS. The interplay between sleep and ecophysiology, behaviour and responses to environmental change in fish. J Exp Biol 2024; 227:jeb247138. [PMID: 38860399 PMCID: PMC11213526 DOI: 10.1242/jeb.247138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Evidence of behavioural sleep has been observed in every animal species studied to date, but current knowledge of the behaviour, neurophysiology and ecophysiology associated with sleep is concentrated on mammals and birds. Fish are a hugely diverse group that can offer novel insights into a variety of sleep-related behaviours across environments, but the ecophysiological relevance of sleep in fish has been largely overlooked. Here, we systematically reviewed the literature to assess the current breadth of knowledge on fish sleep, and surveyed the diverse physiological effects and behaviours associated with sleep. We also discuss possible ways in which unstudied external factors may alter sleep behaviours. For example, predation risk may alter sleep patterns, as has been shown in mammalian, avian and reptilian species. Other environmental factors - such as water temperature and oxygen availability - have the potential to alter sleep patterns in fish differently than for terrestrial endotherms. Understanding the ecological influences on sleep in fish is vital, as sleep deprivation has the potential to affect waking behaviour and fitness owing to cognitive and physiological impairments, possibly affecting ecological phenomena and sensitivity to environmental stressors in ways that have not been considered.
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Affiliation(s)
- Helena Norman
- School of Biodiversity, One Health, and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Amelia Munson
- School of Biodiversity, One Health, and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Daphne Cortese
- School of Biodiversity, One Health, and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Barbara Koeck
- School of Biodiversity, One Health, and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
| | - Shaun S. Killen
- School of Biodiversity, One Health, and Comparative Medicine, University of Glasgow, Glasgow G12 8QQ, UK
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3
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Bullock RW, Foster C, Lea JSE. Just keep swimming? Observations of resting behavior in gray reef sharks Carcharhinus amblyrhynchos (Bleeker, 1856). JOURNAL OF FISH BIOLOGY 2024; 104:898-900. [PMID: 37983935 DOI: 10.1111/jfb.15623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 11/06/2023] [Accepted: 11/15/2023] [Indexed: 11/22/2023]
Abstract
Understanding the respiratory modes of sharks has important implications for studying the metabolism, energetics, and behavioral strategies of different species. Here we provide the first reported observations of resting behavior in the gray reef shark Carcharhinus amblyrhynchos, a species typically considered an obligate ram ventilator. Observations were made at several locations in the Republic of Seychelles, where sharks were found resting under reef ledges and were unresponsive to the presence of divers. These findings update our understanding of the respiratory mode of this species and have implications for future research.
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Affiliation(s)
- Robert W Bullock
- Save Our Seas Foundation-D'Arros Research Centre, Geneva, Switzerland
| | | | - James S E Lea
- Save Our Seas Foundation, Geneva, Switzerland
- Department of Zoology, University of Cambridge, Cambridge, UK
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4
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Arnette S, Saffarian J, Ferry L, Farina S. Effect of parabranchial position on ventilatory pressures in the Pacific spiny dogfish (Squalus suckleyi). ZOOLOGY 2023; 159:126106. [PMID: 37541031 DOI: 10.1016/j.zool.2023.126106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 08/06/2023]
Abstract
The mechanics of ventilation in elasmobranchs have been described as a two-pump system which is dependent on the generation of differential pressures between the orobranchial and parabranchial cavities. However, this general model does not take into account sources of variation in parabranchial form and function. For example, the relative pressures that drive flow in each parabranchial chamber during ventilation remain largely unexplored. To address this gap, parabranchial pressures were collected from the Pacific spiny dogfish (Squalus suckleyi, n = 12) during routine ventilation using transducers inserted into parabranchial chambers 2, 3, and 5, numbered anteriorly to posteriorly. Pressure amplitudes collected from the three chambers displayed an attenuation of pressure amplitudes posteriorly, as well as differential, modular use of parabranchial chamber five These observations have implications for the functioning of the ventilatory pump and indicate distinct ventilatory modes, leading us to propose a new model to describe ventilation in Squalus suckleyi.
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Affiliation(s)
- Sarah Arnette
- New College, Department of Math and Natural Sciences, Arizona State University West, 4701 W. Thunderbird Rd, Glendale, AZ 85306, United States; Friday Harbor Laboratories, University of Washington, 620 University Rd, Friday Harbor, WA 92150, United States.
| | - Jacob Saffarian
- Friday Harbor Laboratories, University of Washington, 620 University Rd, Friday Harbor, WA 92150, United States; UC Berkeley, Rausser College of Natural Resources, 110 Sproul Hall, Berkeley, CA 94720, United States
| | - Lara Ferry
- New College, Department of Math and Natural Sciences, Arizona State University West, 4701 W. Thunderbird Rd, Glendale, AZ 85306, United States
| | - Stacy Farina
- Friday Harbor Laboratories, University of Washington, 620 University Rd, Friday Harbor, WA 92150, United States; Department of Biology, Howard University, 415 College St NW, Washington, DC 20059, United States
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Tan H, Martin JM, Alton LA, Lesku JA, Wong BBM. Widespread psychoactive pollutant augments daytime restfulness and disrupts diurnal activity rhythms in fish. CHEMOSPHERE 2023; 326:138446. [PMID: 36940830 DOI: 10.1016/j.chemosphere.2023.138446] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 03/13/2023] [Accepted: 03/17/2023] [Indexed: 06/18/2023]
Abstract
Pharmaceutical pollution is a major driver of global change, with the capacity to alter key behavioural and physiological traits in exposed animals. Antidepressants are among the most commonly detected pharmaceuticals in the environment. Despite well-documented pharmacological effects of antidepressants on sleep in humans and other vertebrates, very little is known about their ecologically relevant impacts as pollutants on non-target wildlife. Accordingly, we investigated the effects of acute 3-day exposure of eastern mosquitofish (Gambusia holbrooki) to field-realistic levels (nominal concentrations: 30 and 300 ng/L) of the widespread psychoactive pollutant, fluoxetine, on diurnal activity patterns and restfulness, as indicators of disruptions to sleep. We show that exposure to fluoxetine disrupted diel activity patterns, which was driven by augmentation of daytime inactivity. Specifically, unexposed control fish were markedly diurnal, swimming farther during the day and exhibiting longer periods and more bouts of inactivity at night. However, in fluoxetine-exposed fish, this natural diel rhythm was eroded, with no differences in activity or restfulness observed between the day and night. As a misalignment in the circadian rhythm has been shown to adversely affect fecundity and lifespan in animals, our findings reveal a potentially serious threat to the survival and reproductive success of pollutant-exposed wildlife.
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Affiliation(s)
- Hung Tan
- School of Biological Sciences, Monash University, Melbourne, Australia.
| | - Jake M Martin
- School of Biological Sciences, Monash University, Melbourne, Australia; Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden; Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Lesley A Alton
- School of Biological Sciences, Monash University, Melbourne, Australia
| | - John A Lesku
- School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia; Research Centre for Future Landscapes, La Trobe University, Melbourne, Australia
| | - Bob B M Wong
- School of Biological Sciences, Monash University, Melbourne, Australia
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6
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Rattenborg NC, Ungurean G. The evolution and diversification of sleep. Trends Ecol Evol 2023; 38:156-170. [PMID: 36411158 DOI: 10.1016/j.tree.2022.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/17/2022] [Accepted: 10/24/2022] [Indexed: 11/19/2022]
Abstract
The evolutionary origins of sleep and its sub-states, rapid eye movement (REM) and non-REM (NREM) sleep, found in mammals and birds, remain a mystery. Although the discovery of a single type of sleep in jellyfish suggests that sleep evolved much earlier than previously thought, it is unclear when and why sleep diversified into multiple types of sleep. Intriguingly, multiple types of sleep have recently been found in animals ranging from non-avian reptiles to arthropods to cephalopods. Although there are similarities between these states and those found in mammals and birds, notable differences also exist. The diversity in the way sleep is expressed confounds attempts to trace the evolution of sleep states, but also serves as a rich resource for exploring the functions of sleep.
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Affiliation(s)
- Niels C Rattenborg
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany.
| | - Gianina Ungurean
- Max Planck Institute for Biological Intelligence (in foundation), Seewiesen, Germany
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Wheeler CR, Kneebone J, Heinrich D, Strugnell JM, Mandelman JW, Rummer JL. Diel Rhythm and Thermal Independence of Metabolic Rate in a Benthic Shark. J Biol Rhythms 2022; 37:484-497. [PMID: 35822624 DOI: 10.1177/07487304221107843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biological rhythms that are mediated by exogenous factors, such as light and temperature, drive the physiology of organisms and affect processes ranging from cellular to population levels. For elasmobranchs (i.e. sharks, rays, and skates), studies documenting diel activity and movement patterns indicate that many species are crepuscular or nocturnal in nature. However, few studies have investigated the rhythmicity of elasmobranch physiology to understand the mechanisms underpinning these distinct patterns. Here, we assess diel patterns of metabolic rates in a small meso-predator, the epaulette shark (Hemiscyllium ocellatum), across ecologically relevant temperatures and upon acutely removing photoperiod cues. This species possibly demonstrates behavioral sleep during daytime hours, which is supported herein by low metabolic rates during the day and a 1.7-fold increase in metabolic rates at night. From spring to summer seasons, where average average water temperature temperatures for this species range 24.5 to 28.5 °C, time of day, and not temperature, had the strongest influence on metabolic rate. These results indicate that this species, and perhaps other similar species from tropical and coastal environments, may have physiological mechanisms in place to maintain metabolic rate on a seasonal time scale regardless of temperature fluctuations that are relevant to their native habitats.
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Affiliation(s)
- Carolyn R Wheeler
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,School for the Environment, The University of Massachusetts Boston, Boston, Massachusetts
| | - Jeff Kneebone
- Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, Massachusetts
| | - Dennis Heinrich
- College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Jan M Strugnell
- Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Queensland, Australia.,Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Victoria, Australia
| | - John W Mandelman
- School for the Environment, The University of Massachusetts Boston, Boston, Massachusetts.,Anderson Cabot Center for Ocean Life, New England Aquarium, Boston, Massachusetts
| | - Jodie L Rummer
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
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8
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Location, Location, Location! Evaluating Space Use of Captive Aquatic Species—A Case Study with Elasmobranchs. JOURNAL OF ZOOLOGICAL AND BOTANICAL GARDENS 2022. [DOI: 10.3390/jzbg3020020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The space use of captive animals has been reliably used as a tool to measure animal welfare in recent years. However, most analyses of space use focus primarily on terrestrial animals, with very little emphasis placed on the space use of aquatic animals. By comparing the space use of these animals to their natural histories and what would be expected of them physiologically, a general assessment of their overall welfare can be obtained. Using the Zoomonitor program, this study investigated the space use of five elasmobranch species housed in a captive aquatic environment: a blacktip reef shark (Carcharhinus melanopterus), a nurse shark (Ginglymostoma cirratum), a smooth dogfish (Musteluscanis), a bonnethead shark (Sphyrna tiburo), and a blacknose shark (Carcharhinus acronotus). The exhibit was delineated into five different zones: three represented the animal locations along the X/Y axis (‘Exhibit Use’), and two zones were related to the Z-axis (‘Depth Use’). The location of each individual on both the X/Y and Z axes was recorded during each observation. Heat maps generated from the Zoomonitor program were used in conjunction with the Spread of Participation Index (SPI) to interpret the data. It was found that while all the individuals used their given space differently, the Exhibit Use was relatively even overall (the SPI values ranged from 0.0378 to 0.367), while the Depth Use was more uneven (the SPI ranged from 0.679 to 0.922). These results mostly reflected what would be expected based on the species’ natural histories. However, for the smooth dogfish, the observed Exhibit Use and activity patterns revealed a mismatch between the anticipated and the actual results, leading to further interventions. As demonstrated here, space use results can be utilized to make positive changes to husbandry routines and enclosure designs for aquatic individuals; they are thus an important additional welfare measure to consider for aquatic species.
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9
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Kelly ML, Collins SP, Lesku JA, Hemmi JM, Collin SP, Radford CA. Energy conservation characterizes sleep in sharks. Biol Lett 2022; 18:20210259. [PMID: 35259943 PMCID: PMC8915397 DOI: 10.1098/rsbl.2021.0259] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Sharks represent the earliest group of jawed vertebrates and as such, they may provide original insight for understanding the evolution of sleep in more derived animals. Unfortunately, beyond a single behavioural investigation, very little is known about sleep in these ancient predators. As such, recordings of physiological indicators of sleep in sharks have never been reported. Reduced energy expenditure arising from sustained restfulness and lowered metabolic rate during sleep have given rise to the hypothesis that sleep plays an important role for energy conservation. To determine whether this idea applies also to sharks, we compared metabolic rates of draughtsboard sharks (Cephaloscyllium isabellum) during periods ostensibly thought to be sleep, along with restful and actively swimming sharks across a 24 h period. We also investigated behaviours that often characterize sleep in other animals, including eye closure and postural recumbency, to establish relationships between physiology and behaviour. Overall, lower metabolic rate and a flat body posture reflect sleep in draughtsboard sharks, whereas eye closure is a poorer indication of sleep. Our results support the idea for the conservation of energy as a function of sleep in these basal vertebrates.
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Affiliation(s)
- Michael L Kelly
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Selwyn P Collins
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
| | - John A Lesku
- School of Life Sciences, La Trobe University, Melbourne, Australia
| | - Jan M Hemmi
- School of Biological Sciences, The University of Western Australia, Perth, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia
| | - Shaun P Collin
- School of Life Sciences, La Trobe University, Melbourne, Australia.,Oceans Institute, The University of Western Australia, Perth, Australia.,Oceans Graduate School, The University of Western Australia, Perth, Australia
| | - Craig A Radford
- Institute of Marine Science, Leigh Marine Laboratory, The University of Auckland, Auckland, New Zealand
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Mohanty NP, Wagener C, Herrel A, Thaker M. The ecology of sleep in non-avian reptiles. Biol Rev Camb Philos Soc 2021; 97:505-526. [PMID: 34708504 DOI: 10.1111/brv.12808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 10/10/2021] [Accepted: 10/18/2021] [Indexed: 01/10/2023]
Abstract
Sleep is ubiquitous in the animal kingdom and yet displays considerable variation in its extent and form in the wild. Ecological factors, such as predation, competition, and microclimate, therefore are likely to play a strong role in shaping characteristics of sleep. Despite the potential for ecological factors to influence various aspects of sleep, the ecological context of sleep in non-avian reptiles remains understudied and without systematic direction. In this review, we examine multiple aspects of reptilian sleep, including (i) habitat selection (sleep sites and their spatio-temporal distribution), (ii) individual-level traits, such as behaviour (sleep postures), morphology (limb morphometrics and body colour), and physiology (sleep architecture), as well as (iii) inter-individual interactions (intra- and inter-specific). Throughout, we discuss the evidence of predation, competition, and thermoregulation in influencing sleep traits and the possible evolutionary consequences of these sleep traits for reptile sociality, morphological specialisation, and habitat partitioning. We also review the ways in which sleep ecology interacts with urbanisation, biological invasions, and climate change. Overall, we not only provide a systematic evaluation of the conceptual and taxonomic biases in the existing literature on reptilian sleep, but also use this opportunity to organise the various ecological hypotheses for sleep characteristics. By highlighting the gaps and providing a prospectus of research directions, our review sets the stage for understanding sleep ecology in the natural world.
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Affiliation(s)
- Nitya P Mohanty
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
| | - Carla Wagener
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - Anthony Herrel
- Département Adaptations du Vivant, MECADEV UMR7179 CNRS/MNHN, Paris, France
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
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