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Waller MJ, Humphries NE, Womersley FC, Loveridge A, Jeffries AL, Watanabe Y, Payne N, Semmens J, Queiroz N, Southall EJ, Sims DW. The vulnerability of sharks, skates, and rays to ocean deoxygenation: Physiological mechanisms, behavioral responses, and ecological impacts. JOURNAL OF FISH BIOLOGY 2024. [PMID: 38852616 DOI: 10.1111/jfb.15830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 05/08/2024] [Accepted: 05/20/2024] [Indexed: 06/11/2024]
Abstract
Levels of dissolved oxygen in open ocean and coastal waters are decreasing (ocean deoxygenation), with poorly understood effects on marine megafauna. All of the more than 1000 species of elasmobranchs (sharks, skates, and rays) are obligate water breathers, with a variety of life-history strategies and oxygen requirements. This review demonstrates that although many elasmobranchs typically avoid hypoxic water, they also appear capable of withstanding mild to moderate hypoxia with changes in activity, ventilatory responses, alterations to circulatory and hematological parameters, and morphological alterations to gill structures. However, such strategies may be insufficient to withstand severe, progressive, or prolonged hypoxia or anoxia where anaerobic metabolic pathways may be used for limited periods. As water temperatures increase with climate warming, ectothermic elasmobranchs will exhibit elevated metabolic rates and are likely to be less able to tolerate the effects of even mild hypoxia associated with deoxygenation. As a result, sustained hypoxic conditions in warmer coastal or surface-pelagic waters are likely to lead to shifts in elasmobranch distributions. Mass mortalities of elasmobranchs linked directly to deoxygenation have only rarely been observed but are likely underreported. One key concern is how reductions in habitat volume as a result of expanding hypoxia resulting from deoxygenation will influence interactions between elasmobranchs and industrial fisheries. Catch per unit of effort of threatened pelagic sharks by longline fisheries, for instance, has been shown to be higher above oxygen minimum zones compared to adjacent, normoxic regions, and attributed to vertical habitat compression of sharks overlapping with increased fishing effort. How a compound stressor such as marine heatwaves alters vulnerability to deoxygenation remains an open question. With over a third of elasmobranch species listed as endangered, a priority for conservation and management now lies in understanding and mitigating ocean deoxygenation effects in addition to population declines already occurring from overfishing.
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Affiliation(s)
- Matt J Waller
- Marine Biological Association, The Laboratory, Plymouth, UK
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | | | | | | | - Amy L Jeffries
- Marine Biological Association, The Laboratory, Plymouth, UK
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
| | - Yuuki Watanabe
- Research Center for Integrative Evolutionary Science, The Graduate University for Advanced Studies, SOKENDAI, Kanagawa, Japan
| | - Nicholas Payne
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Jayson Semmens
- Institue for Marine and Antarctic Studies, University of Tasmania, Hobart, Australia
| | - Nuno Queiroz
- CIBIO/InBIO, Universidade do Porto, Vairão, Portugal
- BIOPOLIS, Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
| | | | - David W Sims
- Marine Biological Association, The Laboratory, Plymouth, UK
- Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, UK
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Parker KS, El N, Buldo EC, MacCormack TJ. Mechanisms of PVP-functionalized silver nanoparticle toxicity in fish: Intravascular exposure disrupts cardiac pacemaker function and inhibits Na +/K +-ATPase activity in heart, but not gill. Comp Biochem Physiol C Toxicol Pharmacol 2024; 277:109837. [PMID: 38218567 DOI: 10.1016/j.cbpc.2024.109837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Revised: 12/21/2023] [Accepted: 01/08/2024] [Indexed: 01/15/2024]
Abstract
Polyvinylpyrrolidone-functionalized silver nanoparticles (nAgPVP) are popular in consumer products for their colloidal stability and antimicrobial activity. Whole lake additions of nAgPVP cause long term, ecosystem-scale changes in fish populations but the mechanisms underlying this effect are unclear. We have previously shown that in fish, nAgPVP impairs cardiac contractility and Na+/K+-ATPase (NKA) activity in vitro, raising the possibility that heart dysfunction could underlie population-level exposure effects. The goal of this study was to determine if nAgPVP influences the control of heart rate (fh), blood pressure, or cardiac NKA activity in vivo. First, a dose-response curve for the effects of 5 nm nAgPVP on contractility was completed on isometrically contracting ventricular muscle preparations from Arctic char (Salvelinus alpinus) and showed that force production was lowest at 500 μg L-1 and maximum pacing frequency increased with nAgPVP concentration. Stroke volume, cardiac output, and power output were maintained in isolated working heart preparations from brook char (Salvelinus fontinalis) exposed to 700 μg L-1 nAgPVP. Both fh and blood pressure were elevated after 24 h in brook char injected with 700 μg kg body mass-1 nAgPVP and fh was insensitive to modulation with blockers of β-adrenergic and muscarinic cholinergic receptors. Na+/K+-ATPase activity was significantly lower in heart, but not gill of nAgPVP injected fish. The results indicate that nAgPVP influences cardiac function in vivo by disrupting regulation of the pacemaker and cardiomyocyte ionoregulation. Impaired fh regulation may prevent fish from appropriately responding to environmental or social stressors and affect their ability to survive.
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Affiliation(s)
- K S Parker
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB, Canada
| | - N El
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB, Canada
| | - E C Buldo
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB, Canada
| | - T J MacCormack
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB, Canada.
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Deutsch C, Penn JL, Lucey N. Climate, Oxygen, and the Future of Marine Biodiversity. ANNUAL REVIEW OF MARINE SCIENCE 2024; 16:217-245. [PMID: 37708422 DOI: 10.1146/annurev-marine-040323-095231] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/16/2023]
Abstract
The ocean enabled the diversification of life on Earth by adding O2 to the atmosphere, yet marine species remain most subject to O2 limitation. Human industrialization is intensifying the aerobic challenges to marine ecosystems by depleting the ocean's O2 inventory through the global addition of heat and local addition of nutrients. Historical observations reveal an ∼2% decline in upper-ocean O2 and accelerating reports of coastal mass mortality events. The dynamic balance of O2 supply and demand provides a unifying framework for understanding these phenomena across scales from the global ocean to individual organisms. Using this framework, we synthesize recent advances in forecasting O2 loss and its impacts on marine biogeography, biodiversity, and biogeochemistry. We also highlight three outstanding uncertainties: how long-term global climate change intensifies ocean weather events in which simultaneous heat and hypoxia create metabolic storms, how differential species O2 sensitivities alter the structure of ecological communities, and how global O2 loss intersects with coastal eutrophication. Projecting these interacting impacts on future marine ecosystems requires integration of climate dynamics, biogeochemistry, physiology, and ecology, evaluated with an eye on Earth history. Reducing global and local impacts of warming and O2 loss will be essential if humankind is to preserve the health and biodiversity of the future ocean.
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Affiliation(s)
- Curtis Deutsch
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA;
- High Meadows Environmental Institute, Princeton University, Princeton, New Jersey, USA
| | - Justin L Penn
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA;
| | - Noelle Lucey
- High Meadows Environmental Institute, Princeton University, Princeton, New Jersey, USA
- Smithsonian Tropical Research Institute, Balboa Ancón, Panama
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Skeeles MR, Scheuffele H, Clark TD. Supplemental oxygen does not improve growth but can enhance reproductive capacity of fish. Proc Biol Sci 2023; 290:20231779. [PMID: 37909085 PMCID: PMC10618859 DOI: 10.1098/rspb.2023.1779] [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] [Received: 08/07/2023] [Accepted: 10/05/2023] [Indexed: 11/02/2023] Open
Abstract
Fish tend to grow faster as the climate warms but attain a smaller adult body size following an earlier age at sexual maturation. Despite the apparent ubiquity of this phenomenon, termed the temperature-size rule (TSR), heated scientific debates have revealed a poor understanding of the underlying mechanisms. At the centre of these debates are prominent but marginally tested hypotheses which implicate some form of 'oxygen limitation' as the proximate cause. Here, we test the role of oxygen limitation in the TSR by rearing juvenile Galaxias maculatus for a full year in current-day (15°C) and forecasted (20°C) summer temperatures while providing half of each temperature group with supplemental oxygen (hyperoxia). True to the TSR, fish in the warm treatments grew faster and reached sexual maturation earlier than their cooler conspecifics. Yet, despite supplemental oxygen significantly increasing maximum oxygen uptake rate, our findings contradict leading hypotheses by showing that the average size at sexual maturation and the adult body size did not differ between normoxia and hyperoxia groups. We did, however, discover that hyperoxia extended the reproductive window, independent of fish size and temperature. We conclude that the intense resource investment in reproduction could expose a bottleneck where oxygen becomes a limiting factor.
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Affiliation(s)
- Michael R. Skeeles
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia
| | - Hanna Scheuffele
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia
| | - Timothy D. Clark
- School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia
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Woods HA, Moran AL, Atkinson D, Audzijonyte A, Berenbrink M, Borges FO, Burnett KG, Burnett LE, Coates CJ, Collin R, Costa-Paiva EM, Duncan MI, Ern R, Laetz EMJ, Levin LA, Lindmark M, Lucey NM, McCormick LR, Pierson JJ, Rosa R, Roman MR, Sampaio E, Schulte PM, Sperling EA, Walczyńska A, Verberk WCEP. Integrative Approaches to Understanding Organismal Responses to Aquatic Deoxygenation. THE BIOLOGICAL BULLETIN 2022; 243:85-103. [PMID: 36548975 DOI: 10.1086/722899] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
AbstractOxygen bioavailability is declining in aquatic systems worldwide as a result of climate change and other anthropogenic stressors. For aquatic organisms, the consequences are poorly known but are likely to reflect both direct effects of declining oxygen bioavailability and interactions between oxygen and other stressors, including two-warming and acidification-that have received substantial attention in recent decades and that typically accompany oxygen changes. Drawing on the collected papers in this symposium volume ("An Oxygen Perspective on Climate Change"), we outline the causes and consequences of declining oxygen bioavailability. First, we discuss the scope of natural and predicted anthropogenic changes in aquatic oxygen levels. Although modern organisms are the result of long evolutionary histories during which they were exposed to natural oxygen regimes, anthropogenic change is now exposing them to more extreme conditions and novel combinations of low oxygen with other stressors. Second, we identify behavioral and physiological mechanisms that underlie the interactive effects of oxygen with other stressors, and we assess the range of potential organismal responses to oxygen limitation that occur across levels of biological organization and over multiple timescales. We argue that metabolism and energetics provide a powerful and unifying framework for understanding organism-oxygen interactions. Third, we conclude by outlining a set of approaches for maximizing the effectiveness of future work, including focusing on long-term experiments using biologically realistic variation in experimental factors and taking truly cross-disciplinary and integrative approaches to understanding and predicting future effects.
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