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Ostrowski A, Connolly RM, Brown CJ, Sievers M. Stressor fluctuations alter mechanisms of seagrass community responses relative to static stressors. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 900:165865. [PMID: 37516181 DOI: 10.1016/j.scitotenv.2023.165865] [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: 05/25/2023] [Revised: 07/17/2023] [Accepted: 07/26/2023] [Indexed: 07/31/2023]
Abstract
Ecosystems are increasingly affected by multiple anthropogenic stressors that contribute to habitat degradation and loss. Natural ecosystems are highly dynamic, yet multiple stressor experiments often ignore variability in stressor intensity and do not consider how effects could be mediated across trophic levels, with implications for models that underpin stressor management. Here, we investigated the in situ effects of changes in stressor intensity (i.e., fluctuations) and synchronicity (i.e., timing of fluctuations) on a seagrass community, applying the stressors reduced light and physical disturbance to the sediment. We used structural equation models (SEMs) to identify causal effects of dynamic multiple stressors on seagrass shoot density and leaf surface area, and abundance of associated crustaceans. Responses depended on whether stressor intensities fluctuated or remained static. Relative to static stressor exposure at the end of the experiment, shoot density, leaf surface area, and crustacean abundance all declined under in-phase (synchronous; 17, 33, and 30 % less, respectively) and out-of-phase (asynchronous; 11, 28, and 39 % less, respectively) fluctuating treatments. Static treatment increased seagrass leaf surface area and crustacean abundance relative to the control group. We hypothesised that crustacean responses are mediated by changes in seagrass; however, causal analysis found only weak evidence for a mediation effect via leaf surface area. Changes in crustacean abundance, therefore, were primarily a direct response to stressors. Our results suggest that the mechanisms underpinning stress responses change when stressors fluctuate. For instance, increased leaf surface area under static stress could be caused by seagrass acclimating to low light, whereas no response under fluctuating stressors suggests an acclimation response was not triggered. The SEMs also revealed that community responses to the stressors can be independent of one another. Therefore, models based on static experiments may be representing ecological mechanisms not observed in natural ecosystems, and underestimating the impacts of stressors on ecosystems.
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Affiliation(s)
- Andria Ostrowski
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, QLD 4222, Australia.
| | - Rod M Connolly
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, QLD 4222, Australia
| | - Christopher J Brown
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, QLD 4222, Australia
| | - Michael Sievers
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, QLD 4222, Australia
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2
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Duvall MS, Hagy JD, Ammerman JW, Tedesco MA. High-frequency dissolved oxygen dynamics in an urban estuary, the Long Island Sound. ESTUARIES AND COASTS : JOURNAL OF THE ESTUARINE RESEARCH FEDERATION 2023; 47:415-430. [PMID: 38993945 PMCID: PMC11235145 DOI: 10.1007/s12237-023-01278-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/17/2023] [Accepted: 09/11/2023] [Indexed: 07/13/2024]
Abstract
The seasonal occurrence of deep-water hypoxia in western Long Island Sound (LIS) has been documented for decades by water quality cruise surveys and fixed mooring buoys. While previous studies have focused on factors modulating bottom dissolved oxygen (DO) at subtidal timescales, here we analyze continuous timeseries data from a moored buoy during summers 2021 and 2022 to examine factors controlling high-frequency fluctuations in surface and bottom DO at diurnal and semidiurnal timescales. Fluctuations in surface DO at diurnal timescales are associated with biological production, while fluctuations in bottom DO near semidiurnal timescales are associated with horizontal advection of DO by tides from the upper East River tidal strait into western LIS. Results from timeseries analysis are supported by weekly cruise surveys that resolve horizontal and vertical DO gradients in the western narrows. However, inferences regarding the duration of hypoxia during a given summer vary across datasets in part because weekly survey data do not resolve dominant timescales of variability within a particular summer. While prior studies have illustrated the importance of nutrient loading, stratification, and wind in controlling the development of hypoxia, the results presented here demonstrate the role of tidal advection in modulating hypoxia in far western LIS. Despite stronger stratification in 2021, the duration of hypoxia was 11.1 days shorter compared to 2022 in part due to greater advection of DO by tidal currents that intermittently increased bottom DO near the buoy. Furthermore, five-year averaged hypoxic area in the western narrows has increased since 2017, which highlights the spatially variable response of DO to nutrient load reductions. Future analysis of hypoxia in LIS should focus on leveraging high-frequency information contained in continuous datasets to improve estimates of hypoxia based on less temporally resolved water quality surveys.
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Affiliation(s)
- Melissa S Duvall
- U.S. Environmental Protection Agency, Long Island Sound Office, 888 Washington Blvd., Stamford, CT 06904 USA
| | - James D Hagy
- U.S. Environmental Protection Agency, Office of Research and Development, 27 Tarzwell Dr., Narragansett, RI 02882 USA
| | - James W Ammerman
- Long Island Sound Study/NEIWPCC, 888 Washington Blvd., Stamford, CT 06904 USA
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794
| | - Mark A Tedesco
- U.S. Environmental Protection Agency, Long Island Sound Office, 888 Washington Blvd., Stamford, CT 06904 USA
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3
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Ostrowski A, Connolly RM, Brown CJ, Sievers M. Fluctuating fortunes: Stressor synchronicity and fluctuating intensity influence biological impacts. Ecol Lett 2022; 25:2611-2623. [PMID: 36217804 PMCID: PMC9828260 DOI: 10.1111/ele.14120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 08/22/2022] [Accepted: 09/07/2022] [Indexed: 01/12/2023]
Abstract
Ecosystems remain under enormous pressure from multiple anthropogenic stressors. Manipulative experiments evaluating stressor interactions and impacts mostly apply stressors under static conditions without considering how variable stressor intensity (i.e. fluctuations) and synchronicity (i.e. timing of fluctuations) affect biological responses. We ask how variable stressor intensity and synchronicity, and interaction type, can influence how multiple stressors affect seagrass. At the highest intensities, fluctuating stressors applied asynchronously reduced seagrass biomass 36% more than for static stressors, yet no such difference occurred for photosynthetic capacity. Testing three separate hypotheses to predict underlying drivers of differences in biological responses highlighted alternative modes of action dependent on how stressors fluctuated over time. Given that environmental conditions are constantly changing, assessing static stressors may lead to inaccurate predictions of cumulative effects. Translating multiple stressor experiments to the real world, therefore, requires considering variability in stressor intensity and the synchronicity of fluctuations.
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Affiliation(s)
- Andria Ostrowski
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and ScienceGriffith UniversityGold CoastQueenslandAustralia
| | - Rod M. Connolly
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and ScienceGriffith UniversityGold CoastQueenslandAustralia
| | - Christopher J. Brown
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and ScienceGriffith UniversityGold CoastQueenslandAustralia
| | - Michael Sievers
- Coastal and Marine Research Centre, Australian Rivers Institute, School of Environment and ScienceGriffith UniversityGold CoastQueenslandAustralia
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Frommel AY, Lye SLR, Brauner CJ, Hunt BPV. Air exposure moderates ocean acidification effects during embryonic development of intertidally spawning fish. Sci Rep 2022; 12:12270. [PMID: 35851610 PMCID: PMC9293985 DOI: 10.1038/s41598-022-16399-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022] Open
Abstract
Ocean acidification can negatively impact the early life-stages of marine fish, due to energetic costs incurred by the maintenance of acid–base homeostasis, leaving less energy available for growth and development. The embryos of intertidally spawning fishes, such as Pacific herring, are often air exposed for hours. We hypothesized that air exposure would be beneficial to the developing embryo due to a higher oxygen availability (and thus reduced metabolic costs to secure adequate oxygen) and permitting excess CO2 associated with ocean acidification to be off-gassed during emersion. To investigate this, we reared Pacific herring (Clupea pallasii) embryos under three tidal regimes (subtidal: fully immersed, low intertidal: 2 × 2 h air exposure, and high intertidal: 5 + 9 h air exposure) fully crossed with three aquatic CO2 levels (400, 1500 and 3200 µatm) at a water temperature of 9.5 °C and naturally fluctuating air temperature during air exposure. We measured the effects on embryonic development and hatch, as well as carry-over effects on larval development and survival. Air exposure during embryonic development had significant positive effects on growth, condition and survival in larval Pacific herring, with some interactive effects with CO2. Interestingly, CO2 by itself in the fully immersed treatment had no effect, but had significant interactions with air exposure. Our research suggests that air exposure during low tide can be highly beneficial to intertidally spawning fishes and needs to be taken into account in climate change studies and modeling.
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Affiliation(s)
- Andrea Y Frommel
- Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC, V6T 1Z4, Canada. .,Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada. .,Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
| | - Sadie L R Lye
- Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Colin J Brauner
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada
| | - Brian P V Hunt
- Institute for the Oceans and Fisheries, University of British Columbia, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada.,Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2207 Main Mall, Vancouver, BC, V6T 1Z4, Canada.,Hakai Institute, Quadra Island, PO Box 309, Heriot Bay, BC, V0P 1H0, Canada
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Sganga DE, Dahlke FT, Sørensen SR, Butts IAE, Tomkiewicz J, Mazurais D, Servili A, Bertolini F, Politis SN. CO2 induced seawater acidification impacts survival and development of European eel embryos. PLoS One 2022; 17:e0267228. [PMID: 35436318 PMCID: PMC9015118 DOI: 10.1371/journal.pone.0267228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Accepted: 04/04/2022] [Indexed: 11/18/2022] Open
Abstract
Fish embryos may be vulnerable to seawater acidification resulting from anthropogenic carbon dioxide (CO2) emissions or from excessive biological CO2 production in aquaculture systems. This study investigated CO2 effects on embryos of the European eel (Anguilla anguilla), a catadromous fish that is considered at risk from climate change and that is targeted for hatchery production to sustain aquaculture of the species. Eel embryos were reared in three independent recirculation systems with different pH/CO2 levels representing “control” (pH 8.1, 300 μatm CO2), end-of-century climate change (“intermediate”, pH 7.6, 900 μatm CO2) and “extreme” aquaculture conditions (pH 7.1, 3000 μatm CO2). Sensitivity analyses were conducted at 4, 24, and 48 hours post-fertilization (hpf) by focusing on development, survival, and expression of genes related to acute stress response (crhr1, crfr2), stress/repair response (hsp70, hsp90), water and solute transport (aqp1, aqp3), acid-base regulation (nkcc1a, ncc, car15), and inhibitory neurotransmission (GABAAα6b, Gabra1). Results revealed that embryos developing at intermediate pH showed similar survival rates to the control, but egg swelling was impaired, resulting in a reduction in egg size with decreasing pH. Embryos exposed to extreme pH had 0.6-fold decrease in survival at 24 hpf and a 0.3-fold change at 48 compared to the control. These observed effects of acidification were not reflected by changes in expression of any of the here studied genes. On the contrary, differential expression was observed along embryonic development independent of treatment, indicating that the underlying regulating systems are under development and that embryos are limited in their ability to regulate molecular responses to acidification. In conclusion, exposure to predicted end-of-century ocean pCO2 conditions may affect normal development of this species in nature during sensitive early life history stages with limited physiological response capacities, while extreme acidification will negatively influence embryonic survival and development under hatchery conditions.
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Affiliation(s)
- Daniela E. Sganga
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
- * E-mail:
| | | | - Sune R. Sørensen
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
- Billund Aquaculture, Billund, Denmark
| | - Ian A. E. Butts
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, Alabama, United States of America
| | - Jonna Tomkiewicz
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - David Mazurais
- CNRS, IRD, LEMAR, Ifremer, Université de Brest, Plouzané, France
| | - Arianna Servili
- CNRS, IRD, LEMAR, Ifremer, Université de Brest, Plouzané, France
| | - Francesca Bertolini
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Sebastian N. Politis
- National Institute of Aquatic Resources, Technical University of Denmark, Kgs. Lyngby, Denmark
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Schunter C, Jarrold MD, Munday PL, Ravasi T. Diel pCO 2 fluctuations alter the molecular response of coral reef fishes to ocean acidification conditions. Mol Ecol 2021; 30:5105-5118. [PMID: 34402113 DOI: 10.1111/mec.16124] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 08/02/2021] [Accepted: 08/11/2021] [Indexed: 12/26/2022]
Abstract
Environmental partial pressure of CO2 (pCO2 ) variation can modify the responses of marine organisms to ocean acidification, yet the underlying mechanisms for this effect remain unclear. On coral reefs, environmental pCO2 fluctuates on a regular day-night cycle. Effects of future ocean acidification on coral reef fishes might therefore depend on their response to this diel cycle of pCO2 . To evaluate the effects on the brain molecular response, we exposed two common reef fishes (Acanthochromis polyacanthus and Amphiprion percula) to two projected future pCO2 levels (750 and 1,000 µatm) under both stable and diel fluctuating conditions. We found a common signature to stable elevated pCO2 for both species, which included the downregulation of immediate early genes, indicating lower brain activity. The transcriptional programme was more strongly affected by higher average pCO2 in a stable treatment than for fluctuating treatments, but the largest difference in molecular response was between stable and fluctuating pCO2 treatments. This indicates that a response to a change in environmental pCO2 conditions is different for organisms living in a fluctuating than in stable environments. This differential regulation was related to steroid hormones and circadian rhythm (CR). Both species exhibited a marked difference in the expression of CR genes among pCO2 treatments, possibly accommodating a more flexible adaptive approach in the response to environmental changes. Our results suggest that environmental pCO2 fluctuations might enable reef fishes to phase-shift their clocks and anticipate pCO2 changes, thereby avoiding impairments and more successfully adjust to ocean acidification conditions.
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Affiliation(s)
- Celia Schunter
- Swire Institute of Marine Science, School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong SAR
| | - Michael D Jarrold
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Philip L Munday
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Timothy Ravasi
- Australian Research Council Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,Marine Climate Change Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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7
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Schwemmer TG, Baumann H, Murray CS, Molina AI, Nye JA. Acidification and hypoxia interactively affect metabolism in embryos, but not larvae, of the coastal forage fish Menidia menidia. J Exp Biol 2020; 223:jeb228015. [PMID: 33046569 DOI: 10.1242/jeb.228015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 10/05/2020] [Indexed: 11/20/2022]
Abstract
Ocean acidification is occurring in conjunction with warming and deoxygenation as a result of anthropogenic greenhouse gas emissions. Multistressor experiments are critically needed to better understand the sensitivity of marine organisms to these concurrent changes. Growth and survival responses to acidification have been documented for many marine species, but studies that explore underlying physiological mechanisms of carbon dioxide (CO2) sensitivity are less common. We investigated oxygen consumption rates as proxies for metabolic responses in embryos and newly hatched larvae of an estuarine forage fish (Atlantic silverside, Menidia menidia) to factorial combinations of CO2×temperature or CO2×oxygen. Metabolic rates of embryos and larvae significantly increased with temperature, but partial pressure of CO2 (PCO2 ) alone did not affect metabolic rates in any experiment. However, there was a significant interaction between PCO2 and partial pressure of oxygen (PO2 ) in embryos, because metabolic rates were unaffected by PO2 level at ambient PCO2 , but decreased with declining PO2 under elevated PCO2 For larvae, however, PCO2 and PO2 had no significant effect on metabolic rates. Our findings suggest high individual variability in metabolic responses to high PCO2 , perhaps owing to parental effects and time of spawning. We conclude that early life metabolism is largely resilient to elevated PCO2 in this species, but that acidification likely influences energetic responses and thus vulnerability to hypoxia.
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Affiliation(s)
- T G Schwemmer
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - H Baumann
- Department of Marine Sciences, University of Connecticut Avery Point, 1080 Shennecossett Road, Groton, CT 06340, USA
| | - C S Murray
- Washington Ocean Acidification Center, School of Marine and Environmental Affairs, University of Washington, 3710 Brooklyn Ave NE, Seattle, WA 98105, USA
| | - A I Molina
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - J A Nye
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA
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8
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Laubenstein TD, Jarrold MD, Rummer JL, Munday PL. Beneficial effects of diel CO 2 cycles on reef fish metabolic performance are diminished under elevated temperature. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 735:139084. [PMID: 32480143 DOI: 10.1016/j.scitotenv.2020.139084] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 03/06/2020] [Accepted: 04/26/2020] [Indexed: 06/11/2023]
Abstract
Elevated CO2 levels have been shown to affect metabolic performance in some coral reef fishes. However, all studies to date have employed stable elevated CO2 levels, whereas reef habitats can experience substantial diel fluctuations in pCO2 ranging from ±50 to 600 μatm around the mean, fluctuations that are predicted to increase in magnitude by the end of the century. Additionally, past studies have often investigated the effect of elevated CO2 in isolation, despite the fact that ocean temperatures will increase in tandem with CO2 levels. Here, we tested the effects of stable (1000 μatm) versus diel-cycling (1000 ± 500 μatm) elevated CO2 conditions and elevated temperature (+2 °C) on metabolic traits of juvenile spiny damselfish, Acanthochromis polyacanthus. Resting oxygen uptake rates (ṀO2) were higher in fish exposed to stable elevated CO2 conditions when compared to fish from stable control conditions, but were restored to control levels under diel CO2 fluctuations. However, the benefits of diel CO2 fluctuations were diminished at elevated temperature. Factorial aerobic scope showed a similar pattern, but neither maximal ṀO2 nor absolute aerobic scope was affected by CO2 or temperature. Our results suggest that diel CO2 cycles can ameliorate the increased metabolic cost associated with elevated CO2, but elevated temperature diminishes the benefits of diel CO2 cycles. Thus, previous studies may have misestimated the effect of ocean acidification on the metabolic performance of reef fishes by not accounting for environmental CO2 fluctuations. Our findings provide novel insights into the interacting effects of diel CO2 fluctuations and temperature on the metabolic performance of reef fishes.
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Affiliation(s)
- Taryn D Laubenstein
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia.
| | - Michael D Jarrold
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia; College of Science and Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Jodie L Rummer
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
| | - Philip L Munday
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia
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