ORCID Profile
0000-0003-3112-8683
Current Organisation
Murdoch University
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Publisher: Oxford University Press (OUP)
Date: 2020
Abstract: Human activities present aquatic species with numerous of environmental challenges, including excessive nutrient pollution (nitrate) and altered pH regimes (freshwater acidification). In isolation, elevated nitrate and acidic pH can lower the blood oxygen-carrying capacity of aquatic species and cause corresponding declines in key functional performance traits such as growth and locomotor capacity. These factors may pose considerable physiological challenges to organisms but little is known about their combined effects. To characterise the energetic and physiological consequences of simultaneous exposure to nitrate and low pH, we exposed spangled perch (Leiopotherapon unicolor) to a combination of nitrate (0, 50 or 100 mg L−1) and pH (pH 7.0 or 4.0) treatments in a factorial experimental design. Blood oxygen-carrying capacity (haemoglobin concentration, methaemoglobin concentrations and oxygen equilibrium curves), aerobic scope and functional performance traits (growth, swimming performance and post-exercise recovery) were assessed after 28 days of exposure. The oxygen-carrying capacity of fish exposed to elevated nitrate (50 and 100 mg L−1) was compromised due to reductions in haematocrit, functional haemoglobin levels and a 3-fold increase in methaemoglobin concentrations. Oxygen uptake was also impeded due to a right shift in oxygen–haemoglobin binding curves of fish exposed to nitrate and pH 4.0 simultaneously. A reduced blood oxygen-carrying capacity translated to a lowered aerobic scope, and the functional performance of fish (growth and swimming performance and increased post-exercise recovery times) was compromised by the combined effects of nitrate and low pH. These results highlight the impacts on aquatic organisms living in environments threatened by excessive nitrate and acidic pH conditions.
Publisher: Oxford University Press (OUP)
Date: 2021
Abstract: Conservation becomes increasingly complex as climate change exacerbates the multitude of stressors that organisms face. To meet this challenge, multiple stressor research is rapidly expanding, and the majority of this work has highlighted the deleterious effects of stressor interactions. However, there is a growing body of research documenting cross-protection between stressors, whereby exposure to a priming stressor heightens resilience to a second stressor of a different nature. Understanding cross-protection interactions is key to avoiding unrealistic ‘blanket’ conservation approaches, which aim to eliminate all forms of stress. But, a lack of synthesis of cross-protection interactions presents a barrier to integrating these protective benefits into conservation actions. To remedy this, we performed a review of cross-protection interactions among biotic and abiotic stressors within a conservation framework. A total of 66 publications were identified, spanning a erse array of stressor combinations and taxonomic groups. We found that cross-protection occurs in response to naturally co-occurring stressors, as well as novel, anthropogenic stressors, suggesting that cross-protection may act as a ‘pre-adaptation’ to a changing world. Cross-protection interactions occurred in response to both biotic and abiotic stressors, but abiotic stressors have received far more investigation. Similarly, cross-protection interactions were present in a erse array of taxa, but several taxonomic groups (e.g. mammals, birds and hibians) were underrepresented. We conclude by providing an overview of how cross-protection interactions can be integrated into conservation and management actions and discuss how future research in this field may be directed to improve our understanding of how cross-protection may shield animals from global change.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.AQUATOX.2018.05.004
Abstract: Multiple environmental stressors, including nutrient effluents (i.e. nitrates [NO
Publisher: University of Chicago Press
Date: 03-2020
DOI: 10.1086/713252
Publisher: Elsevier BV
Date: 04-2021
Publisher: Wiley
Date: 02-2022
DOI: 10.1111/GCB.16088
Abstract: Climate and land‐use changes are expected to increase the future occurrence of wildfires, with potentially devastating consequences for freshwater species and ecosystems. Wildfires that burn in close proximity to freshwater systems can significantly alter the physicochemical properties of water. Following wildfires and heavy rain, freshwater species must contend with complex combinations of wildfire ash components (nutrients, polycyclic aromatic hydrocarbons, and metals), altered light and thermal regimes, and periods of low oxygen that together can lead to mass mortality events. However, the responses of aquatic fauna to wildfire disturbances are poorly understood. Here we provide a systematic review of available evidence on how aquatic animals respond to and recover from wildfire disturbance. Two databases (Web of Science and Scopus) were used to identify key literature. A total of 83 studies from across 11 countries were identified to have assessed the risk of wildfires on aquatic animals. We provide a summary of the main ecosystem‐level changes associated with wildfires and the main responses of aquatic fauna to such disturbances. We pay special focus to physiological tools and biomarkers used to assess how wildfires impact aquatic animals. We conclude by providing an overview of how physiological biomarkers can further our understanding of wildfire‐related impacts on aquatic fauna, and how different physiological tools can be incorporated into management and conservation plans and serve as early warning signs of wildfire disturbances.
Publisher: Elsevier BV
Date: 05-2022
DOI: 10.1016/J.JTHERBIO.2022.103252
Abstract: The stress history of an ectotherm may be a pivotal predictor of how they cope with rapid spikes in environmental temperature. An understanding of how stressors in habitats and commercial operations affect ectotherm heat tolerance is urgently required so that management actions can be informed by thermal physiology. We hypothesised that brief exposure to mild stress would heighten tolerance to subsequent heat stress, indicative of a cross-tolerance interaction, whereas exposure to severe stress would reduce heat tolerance, reflecting a cross-susceptibility interaction. To test this hypothesis, we assessed how three acute stressors (salinity shock [10 or 33 ppt for 2 h]), air exposure (1 or 5 min) and crowding [95.6 kg m
Publisher: Elsevier BV
Date: 04-2019
DOI: 10.1016/J.CBPA.2019.01.004
Abstract: Aquatic organisms, including important cultured species, are forced to contend with acute changes in water temperature as the frequency and intensity of extreme weather events worsen. Acute temperature spikes are likely to threaten aquaculture species, but dietary intervention may play an important protective role. Increasing the concentration of macronutrients, for ex le dietary fat content, may improve the thermal resilience of aquaculture species, however, this remains unexplored. To evaluate this hypothesis, we used two commercially available diets (20% versus 10% crude fat) to examine if dietary fat content improves the growth performance of juvenile barramundi (Lates calcarifer) while increasing their resilience to acute thermal stress. Fish were fed their assigned diets for 28-days before assessing the upper thermal tolerance (CT
Publisher: The Company of Biologists
Date: 06-2023
DOI: 10.1242/JEB.245644
Abstract: Protective responses are pivotal in aiding organismal persistence in complex, multi-stressor environments. Multiple-stressor research has traditionally focused on the deleterious effects of exposure to concurrent stressors. However, encountering one stressor can sometimes confer heightened tolerance to a second stressor, a phenomenon termed ‘cross-protection’. Cross-protection has been documented in a wide ersity of taxa (spanning the bacteria, fungi, plant and animal kingdoms) and habitats (intertidal, freshwater, rainforests and polar zones) in response to many stressors (e.g. hypoxia, predation, desiccation, pathogens, crowding, salinity, food limitation). Remarkably, cross-protection benefits have also been shown among emerging, anthropogenic stressors, such as heatwaves and microplastics. In this Commentary, we discuss the mechanistic basis and adaptive significance of cross-protection, and put forth the idea that cross-protection will act as a ‘pre-adaptation’ to a changing world. We highlight the critical role that experimental biology has played in disentangling stressor interactions and provide advice for enhancing the ecological realism of laboratory studies. Moving forward, research will benefit from a greater focus on quantifying the longevity of cross-protection responses and the costs associated with this protective response. This approach will enable us to make robust predictions of species' responses to complex environments, without making the erroneous assumption that all stress is deleterious.
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.CBPA.2022.111229
Abstract: The progression of climate warming will expose ectotherms to transient heatwave events and temperatures above their tolerance range at increased frequencies. It is therefore pivotal that we understand species' physiological limits and the capacity for various controls to plastically alter these thresholds. Exercise training could have beneficial impacts on organismal heat tolerance through improvements in cardio-respiratory capacity, but this remains unexplored. Using juvenile Chinook salmon (Oncorhynchus tshawytscha), we tested the hypothesis that exercise training improves heat tolerance through enhancements in oxygen-carrying capacity. Fish were trained once daily at 60% of their maximum sustainable swim speed, U
Publisher: The Company of Biologists
Date: 2020
DOI: 10.1242/JEB.224444
Abstract: Rising temperatures are set to imperil freshwater fishes as climate change ensues unless compensatory strategies are employed. However, the presence of additional stressors, such as elevated nitrate concentrations, may affect the efficacy of compensatory responses. Here, juvenile silver perch (Bidyanus bidyanus) were exposed to current-day summer temperatures (28oC) or a future climate-warming scenario (32oC) and simultaneously exposed to one of three ecologically relevant nitrate concentrations (0, 50 or 100 mg L−1). We measured indicators of fish performance (growth, swimming), aerobic scope (AS) and upper thermal tolerance (CTMAX) to test the hypothesis that nitrate exposure would increase susceptibility to elevated temperatures and limit thermal compensatory responses. After 8 weeks of acclimation, the thermal sensitivity and plasticity of AS and swimming performance were tested at three test temperatures (28, 32, 36oC). The AS of 28oC-acclimated fish declined with increasing temperature, and the effect was more pronounced in nitrate exposed in iduals. In these fish, declines in AS corresponded with poorer swimming performance and a 0.8oC decrease in CTMAX compared to unexposed fish. In contrast, acclimation to 32oC masked the effects of nitrate fish acclimated to 32oC displayed a thermally insensitive phenotype whereby locomotor performance remained unchanged, AS was maintained and CTMAX was increased by ∼1oC irrespective of nitrate treatment compared to fish acclimated to 28oC. Growth was however markedly reduced in 32oC-acclimated compared to 28oC-acclimated fish. Our results indicate that nitrate exposure increases the susceptibility of fish to acute high temperatures, but thermal compensation can override some of these potential detrimental effects.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Oxford University Press (OUP)
Date: 2019
Abstract: Reversing global declines in the abundance and ersity of fishes is dependent on science-based conservation solutions. A wealth of data exist on the ecophysiological constraints of many fishes, but much of this information is underutilized in recovery plans due to a lack of synthesis. Here, we used the imperiled green sturgeon (Acipenser medirostris) as an ex le of how a quantitative synthesis of physiological data can inform conservation plans, identify knowledge gaps and direct future research actions. We reviewed and extracted metadata from peer-reviewed papers on green sturgeon. A total of 105 publications were identified, spanning multiple disciplines, with the primary focus being conservation physiology (23.8%). A meta-analytical approach was chosen to summarize the mean effects of prominent stressors (elevated temperatures, salinity, low food availability and contaminants) on several physiological traits (growth, thermal tolerance, swimming performance and heat shock protein expression). All examined stressors significantly impaired green sturgeon growth, and additional stressor-specific costs were documented. These findings were then used to suggest several management actions, such as mitigating salt intrusion in nursery habitats and maintaining water temperatures within optimal ranges during peak spawning periods. Key data gaps were also identified research efforts have been biased towards juvenile (38.1%) and adult (35.2%) life-history stages, and less data are available for early life-history stages (embryonic, 11.4% yolk-sac larvae, 12.4% and post yolk-sac larvae, 16.2%). Similarly, most data were collected from single-stressor studies (91.4%) and there is an urgent need to understand interactions among stressors as anthropogenic change is multi-variate and dynamic. Collectively, these findings provide an ex le of how meta-analytic reviews are a powerful tool to inform management actions, with the end goal of maximizing conservation gains from research efforts.
Publisher: CRC Press
Date: 18-11-2021
Publisher: Elsevier BV
Date: 02-2021
Publisher: University of Queensland Library
Date: 2020
DOI: 10.14264/EA9709D
Start Date: 2023
End Date: 2025
Funder: Rutherford Foundation Postdoctoral Fellowship
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