ORCID Profile
0000-0003-3514-3653
Current Organisation
University of Canterbury
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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: 04-2021
Publisher: University of Chicago Press
Date: 05-2019
DOI: 10.1086/702828
Abstract: Diving optimality models predict air breathers to routinely e within aerobic limits, but predator avoidance es may be an exception. Lengthening submergence times during a predation threat may enhance survival probability, and we therefore hypothesized that predator avoidance es in juvenile estuarine crocodiles (Crocodylus porosus) would be partially anaerobically fueled. We also predicted that reliance on anaerobic metabolism would increase at elevated temperatures to offset the faster depletion of body oxygen stores. Crocodiles were maintained at 28° and 34°C for 60 d and subsequently underwent simulated predator avoidance e trials at two test temperatures (28° and 34°C). Blood was s led immediately on surfacing to measure plasma lactate concentrations relative to non ing (control) values. Aerobic e limits (cADL min) were also calculated using known body mass and oxygen storage relationships and rates of ing oxygen consumption and compared with observed e durations. Post e plasma lactate levels were elevated beyond resting levels at both test temperatures, indicating that aerobic thresholds were surpassed during simulated predator avoidance es. Similarly, ≥90% of e durations exceeded cADLs at both test temperatures. Post e plasma lactate concentrations were independent of water temperature and thermal acclimation treatment. Together, these findings suggest that reliance on anaerobiosis during simulated predator avoidance es is important regardless of temperature.
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: 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: 11-2015
DOI: 10.1016/J.SCITOTENV.2015.01.089
Abstract: The presence and movements of organisms both reflect and influence the distribution of ecological resources in space and time. The monitoring of animal movement by telemetry devices is being increasingly used to inform management of marine, freshwater and terrestrial ecosystems. Here, we brought together academics, and environmental managers to determine the extent of animal movement research in the Australasian region, and assess the opportunities and challenges in the sharing and reuse of these data. This working group was formed under the Australian Centre for Ecological Analysis and Synthesis (ACEAS), whose overall aim was to facilitate trans-organisational and transdisciplinary synthesis. We discovered that between 2000 and 2012 at least 501 peer-reviewed scientific papers were published that report animal location data collected by telemetry devices from within the Australasian region. Collectively, this involved the capture and electronic tagging of 12 656 animals. The majority of studies were undertaken to address specific management questions rarely were these data used beyond their original intent. We estimate that approximately half (~500) of all animal telemetry projects undertaken remained unpublished, a similar proportion were not discoverable via online resources, and less than 8.8% of all animals tagged and tracked had their data stored in a discoverable and accessible manner. Animal telemetry data contain a wealth of information about how animals and species interact with each other and the landscapes they inhabit. These data are expensive and difficult to collect and can reduce survivorship of the tagged in iduals, which implies an ethical obligation to make the data available to the scientific community. This is the first study to quantify the gap between telemetry devices placed on animals and findings/data published, and presents methods for improvement. Instigation of these strategies will enhance the cost-effectiveness of the research and maximise its impact on the management of natural resources.
Publisher: Elsevier BV
Date: 11-2015
Publisher: The Company of Biologists
Date: 10-2017
DOI: 10.1242/JEB.155440
Abstract: Survival of air-breathing, ing ectotherms is dependent on their capacity to optimise the time available for obligate underwater activities, such as predator avoidance. Submergence times are thermally sensitive, with e durations significantly reduced by increases in water temperature, deeming these animals particularly vulnerable to the effects of climate change. The physiological mechanisms underlying this compromised performance are unclear but are hypothesised to be linked to increased oxygen demand and a reduced capacity for metabolic depression at elevated temperatures. Here, we investigated how water temperature (both acute and chronic exposures) affected the physiology of juvenile estuarine crocodiles (Crocodylus porosus) performing predator avoidance es (i.e. fright- es). Diving oxygen consumption, ‘fright’ bradycardia, haematocrit and haemoglobin (indicators of blood oxygen carrying capacity) were assessed at two test temperatures, reflective of different climate change scenarios (i.e. current summer water temperatures, 28°C, and ‘high’ climate warming, 34°C). Diving oxygen consumption rate increased threefold between 28 and 34°C (Q10=7.4). The capacity to depress oxygen demand was reduced at elevated temperatures, with animals lowering oxygen demand from surface levels by 52.9±27.8% and 27.8±16.5% (means±s.e.m.) at 28°C and 34°C, respectively. Resting and post-fright- e haematocrit and haemoglobin were thermally insensitive. Together these findings suggest decrements in fright- e performance at elevated temperatures stem from increased oxygen demand coupled with a reduced capacity for metabolic depression.
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: Informa UK Limited
Date: 06-11-2012
DOI: 10.3109/07420528.2012.728549
Abstract: Arachnoc a species, commonly called glowworms, are flies whose larvae use light to attract prey. Here we compare rhythmicity in two of the nine described species: the Tasmanian species, Arachnoc a tasmaniensis, which inhabits caves and wet forest, and the eastern Australian mainland species, A. flava, primarily found in subtropical rainforest. Both species show the same nocturnal glowing pattern in external (epigean) environments and the same inhibition of bioluminescence by light and both species show circadian regulation of bioluminescence. We find that the underlying circadian bioluminescence propensity rhythm (BPR) of the two species peaks at opposite phases of the day:night cycle. Larvae of A. flava, placed in constant darkness in the laboratory, bioluminesce during the subjective scotophase, typical of nocturnal animals, whereas A. tasmaniensis shows the opposite tendency, bioluminescing most intensely during the subjective photophase. In A. tasmaniensis, which are exposed to natural day:night cycles, light exposure during the day overrides the high bioluminescence propensity through negative masking and leads to a release of bioluminescence after dusk when the BPR is on the wane. A consequence is that A. tasmaniensis is able to start glowing at any phase of the light:dark cycle as soon as masking by light is released, whereas A. flava is locked into nocturnal bioluminescence. We suggest that the paradoxical BPR of A. tasmaniensis is an adaptation for living in the cave environment. Observations of bioluminescence in colonies of A. tasmaniensis located in the transition from a cave mouth to the dark zone show that glowing is inhibited by light exposure but a peak bioluminescence follows immediately after "dusk" at their location. The substantial difference in the circadian regulation of bioluminescence between the two species probably reflects adaptation to the cave (hypogean) habitat in A. tasmaniensis and the forest (epigean) habitat in A. flava.
Publisher: Oxford University Press (OUP)
Date: 2015
Publisher: The Company of Biologists
Date: 15-02-2021
DOI: 10.1242/JEB.228213
Abstract: Diving ectothermic vertebrates are an important component of many aquatic ecosystems, but the threat of climate warming is particularly salient to this group. Dive durations typically decrease as water temperatures rise yet, we lack an understanding of whether this trend is apparent in all ing ectotherms and how this group will fare under climate warming. We compiled data from 27 studies on 20 ectothermic vertebrate species to quantify the effect of temperature on e durations. Using meta-analytic approaches, we show that, on average, e durations decreased by 11% with every 1°C increase in water temperature. Larger increases in temperature (e.g. +3°C versus +8–9°C) exerted stronger effects on e durations. Although species that respire bimodally are projected to be more resilient to the effects of temperature on e durations than purely aerial breathers, we found no significant difference between these groups. Body mass had a weak impact on mean e durations, with smaller ers being impacted by temperature more strongly. Few studies have examined thermal phenotypic plasticity (N=4) in ing ectotherms, and all report limited plasticity. Average water temperatures in marine and freshwater habitats are projected to increase between 1.5 and 4°C in the next century, and our data suggest that this magnitude of warming could translate to substantial decreases in e durations, by approximately 16–44%. Together, these data shed light on an overlooked threat to ing ectothermic vertebrates and suggest that time available for underwater activities, such as predator avoidance and foraging, may be shortened under future warming.
Publisher: Wiley
Date: 21-09-2021
DOI: 10.1002/JEZ.2412
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/MF13170
Abstract: Fish passage through road culverts is poorly understood, particularly for small-bodied fishes, despite this information being integral to the restoration of waterway connectivity. We assessed the prolonged swimming performance of a small-bodied fish, empire gudgeon (Hypseleotris compressa 3.2–7.7 cm total length, TL), and juvenile Australian bass (Percalates novemaculeata 3.5–7.8 cm TL). Swimming trials were conducted in a hydraulic flume across a range of fixed and increasing velocities in response to acute and long-term thermal treatments. A new statistical approach (Tobit analysis) was used to relate the thermal dependence of swimming endurance to hydraulic characteristics of culverts, providing estimates of maximum water velocity allowing upstream fish passage. Reductions in water temperature of 10°C, similar to those caused by cold-water releases from dams, significantly impaired critical swimming speeds of both species. Traversable water-velocity models identified H. compressa as a weak swimmer, requiring very low water velocities (≤0.10 m s–1 or 2.86 body lengths (BL) s–1) for unrestricted passage, whereas P. novemaculeata was predicted to traverse water velocities of ≤0.39 m s–1 or 12.12 BL s–1. Culvert designs can be improved by limiting water velocities to accommodate weak-swimming fishes and by accounting for the thermal sensitivity of swimming performance.
No related grants have been discovered for Essie Rodgers.