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Journal Cover Conservation Physiology
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  This is an Open Access Journal Open Access journal
   ISSN (Online) 2051-1434
   Published by Oxford University Press (OUP) Homepage  [344 journals]
  • Links between parasitism, energy reserves and fecundity of European
           anchovy, Engraulis encrasicolus, in the northwestern Mediterranean Sea

    • Authors: Ferrer-Maza, D; Lloret, J, Munoz, M, Faliex, E, Vila, S, Sasal, P.
      Abstract: The European anchovy, Engraulis encrasicolus L. 1758, is one of the most sought-after target species in the northwestern Mediterranean Sea. However, this stock currently consists of small individuals, and landings are reported to have decreased considerably. The main purpose of this study was to assess, for the first time, the interrelationships between size, fecundity, energy reserves and parasitism in female anchovies, in order to analyse the potential implications for the health of northwestern Mediterranean anchovy stocks arising from the current shortage of large individuals. Results revealed that smaller individuals show lower fecundity, lower lipid content and a higher intensity of certain parasites. As it is known that smaller individuals now predominate in the population, the relationships found in this study indicate that the health of anchovies from the northwestern Mediterranean is currently impaired.
      PubDate: 2016-01-22T20:40:09-08:00
      DOI: 10.1093/conphys/cov069
      Issue No: Vol. 4, No. 1 (2016)
       
  • Progressive hypoxia decouples activity and aerobic performance of skate
           embryos

    • Authors: Di Santo, V; Tran, A. H, Svendsen, J. C.
      Abstract: Although fish population size is strongly affected by survival during embryonic stages, our understanding of physiological responses to environmental stressors is based primarily on studies of post-hatch fishes. Embryonic responses to acute exposure to changes in abiotic conditions, including increase in hypoxia, could be particularly important in species exhibiting long developmental time, as embryos are unable to select a different environment behaviourally. Given that oxygen is key to metabolic processes in fishes and aquatic hypoxia is becoming more severe and frequent worldwide, organisms are expected to reduce their aerobic performance. Here, we examined the metabolic and behavioural responses of embryos of a benthic elasmobranch fish, the little skate (Leucoraja erinacea), to acute progressive hypoxia, by measuring oxygen consumption and movement (tail-beat) rates inside the egg case. Oxygen consumption rates were not significantly affected by ambient oxygen levels until reaching 45% air saturation (critical oxygen saturation, S crit). Below S crit, oxygen consumption rates declined rapidly, revealing an oxygen conformity response. Surprisingly, we observed a decoupling of aerobic performance and activity, as tail-beat rates increased, rather than matching the declining metabolic rates, at air saturation levels of 55% and below. These results suggest a significantly divergent response at the physiological and behavioural levels. While skate embryos depressed their metabolic rates in response to progressive hypoxia, they increased water circulation inside the egg case, presumably to restore normoxic conditions, until activity ceased abruptly around 9.8% air saturation.
      PubDate: 2016-01-22T20:40:08-08:00
      DOI: 10.1093/conphys/cov067
      Issue No: Vol. 4, No. 1 (2016)
       
  • Prior exposure to capture heightens the corticosterone and behavioural
           responses of little penguins (Eudyptula minor) to acute stress

    • Authors: Carroll, G; Turner, E, Dann, P, Harcourt, R.
      Abstract: Studies of physiology can provide important insight into how animals are coping with challenges in their environment and can signal the potential effects of exposure to human activity in both the short and long term. In this study, we measured the physiological and behavioural response of little penguins (Eudyptula minor) that were naïve to human activity over 30 min of capture and handling. We assessed relationships between corticosterone secretion, behaviour, sex and time of day in order to characterize the determinants of the natural stress response. We then compared the response of these naïve penguins with the responses of female little penguins that had been exposed to research activity (bimonthly nest check and weighing) and to both research activity (monthly nest check and weighing) and evening viewing by tourists. We found that corticosterone concentrations increased significantly over 30 min of capture, with naïve penguins demonstrating a more acute stress response during the day than at night. Penguins that had previously been exposed to handling at the research and research/visitor sites showed elevated corticosterone concentrations and consistently more aggressive behaviour after 30 min compared with naïve birds, although there were no significant differences in baseline corticosterone concentrations. Our findings demonstrate that these little penguins have not habituated to routine capture, but rather mount a heightened physiological and behavioural response to handling by humans. Less invasive research monitoring techniques, such as individual identification with PIT tags and automatic recording and weighing, and a reduction in handling during the day should be considered to mitigate some of the potentially negative effects of disturbance. Given the paucity of data on the long-term consequences of heightened stress on animal physiology, our study highlights the need for further investigation of the relationship between the corticosterone stress response and fitness outcomes, such as breeding success and survival.
      PubDate: 2016-01-19T18:10:10-08:00
      DOI: 10.1093/conphys/cov061
      Issue No: Vol. 4, No. 1 (2016)
       
  • Fisheries conservation on the high seas: linking conservation physiology
           and fisheries ecology for the management of large pelagic fishes

    • Authors: Horodysky, A. Z; Cooke, S. J, Graves, J. E, Brill, R. W.
      Abstract: Populations of tunas, billfishes and pelagic sharks are fished at or over capacity in many regions of the world. They are captured by directed commercial and recreational fisheries (the latter of which often promote catch and release) or as incidental catch or bycatch in commercial fisheries. Population assessments of pelagic fishes typically incorporate catch-per-unit-effort time-series data from commercial and recreational fisheries; however, there have been notable changes in target species, areas fished and depth-specific gear deployments over the years that may have affected catchability. Some regional fisheries management organizations take into account the effects of time- and area-specific changes in the behaviours of fish and fishers, as well as fishing gear, to standardize catch-per-unit-effort indices and refine population estimates. However, estimates of changes in stock size over time may be very sensitive to underlying assumptions of the effects of oceanographic conditions and prey distribution on the horizontal and vertical movement patterns and distribution of pelagic fishes. Effective management and successful conservation of pelagic fishes requires a mechanistic understanding of their physiological and behavioural responses to environmental variability, potential for interaction with commercial and recreational fishing gear, and the capture process. The interdisciplinary field of conservation physiology can provide insights into pelagic fish demography and ecology (including environmental relationships and interspecific interactions) by uniting the complementary expertise and skills of fish physiologists and fisheries scientists. The iterative testing by one discipline of hypotheses generated by the other can span the fundamental–applied science continuum, leading to the development of robust insights supporting informed management. The resulting species-specific understanding of physiological abilities and tolerances can help to improve stock assessments, develop effective bycatch-reduction strategies, predict rates of post-release mortality, and forecast the population effects of environmental change. In this synthesis, we review several examples of these interdisciplinary collaborations that currently benefit pelagic fisheries management.
      PubDate: 2016-01-13T21:40:40-08:00
      DOI: 10.1093/conphys/cov059
      Issue No: Vol. 4, No. 1 (2016)
       
  • Phenotypic variation in metabolism and morphology correlating with animal
           swimming activity in the wild: relevance for the OCLTT (oxygen- and
           capacity-limitation of thermal tolerance), allocation and performance
           models

    • Authors: Baktoft, H; Jacobsen, L, Skov, C, Koed, A, Jepsen, N, Berg, S, Boel, M, Aarestrup, K, Svendsen, J. C.
      Abstract: Ongoing climate change is affecting animal physiology in many parts of the world. Using metabolism, the oxygen- and capacity-limitation of thermal tolerance (OCLTT) hypothesis provides a tool to predict the responses of ectothermic animals to variation in temperature, oxygen availability and pH in the aquatic environment. The hypothesis remains controversial, however, and has been questioned in several studies. A positive relationship between aerobic metabolic scope and animal activity would be consistent with the OCLTT but has rarely been tested. Moreover, the performance model and the allocation model predict positive and negative relationships, respectively, between standard metabolic rate and activity. Finally, animal activity could be affected by individual morphology because of covariation with cost of transport. Therefore, we hypothesized that individual variation in activity is correlated with variation in metabolism and morphology. To test this prediction, we captured 23 wild European perch (Perca fluviatilis) in a lake, tagged them with telemetry transmitters, measured standard and maximal metabolic rates, aerobic metabolic scope and fineness ratio and returned the fish to the lake to quantify individual in situ activity levels. Metabolic rates were measured using intermittent flow respirometry, whereas the activity assay involved high-resolution telemetry providing positions every 30 s over 12 days. We found no correlation between individual metabolic traits and activity, whereas individual fineness ratio correlated with activity. Independent of body length, and consistent with physics theory, slender fish maintained faster mean and maximal swimming speeds, but this variation did not result in a larger area (in square metres) explored per 24 h. Testing assumptions and predictions of recent conceptual models, our study indicates that individual metabolism is not a strong determinant of animal activity, in contrast to individual morphology, which is correlated with in situ activity patterns.
      PubDate: 2016-01-11T17:22:31-08:00
      DOI: 10.1093/conphys/cov055
      Issue No: Vol. 4, No. 1 (2016)
       
  • Evaluating the effect of sample type on American alligator (Alligator
           mississippiensis) analyte values in a point-of-care blood analyser

    • Authors: Hamilton, M. T; Finger, J. W, Winzeler, M. E, Tuberville, T. D.
      Abstract: The assessment of wildlife health has been enhanced by the ability of point-of-care (POC) blood analysers to provide biochemical analyses of non-domesticated animals in the field. However, environmental limitations (e.g. temperature, atmospheric humidity and rain) and lack of reference values may inhibit researchers from using such a device with certain wildlife species. Evaluating the use of alternative sample types, such as plasma, in a POC device may afford researchers the opportunity to delay sample analysis and the ability to use banked samples. In this study, we examined fresh whole blood, fresh plasma and frozen plasma (sample type) pH, partial pressure of carbon dioxide (PCO2), bicarbonate (HCO3 –), total carbon dioxide (TCO2), base excess (BE), partial pressure of oxygen (PO2), oxygen saturation (sO2) and lactate concentrations in 23 juvenile American alligators (Alligator mississippiensis) using an i-STAT CG4+ cartridge. Our results indicate that sample type had no effect on lactate concentration values (F 2,65 = 0.37, P = 0.963), suggesting that the i-STAT analyser can be used reliably to quantify lactate concentrations in fresh and frozen plasma samples. In contrast, the other seven blood parameters measured by the CG4+ cartridge were significantly affected by sample type. Lastly, we were able to collect blood samples from all alligators within 2 min of capture to establish preliminary reference ranges for juvenile alligators based on values obtained using fresh whole blood.
      PubDate: 2016-01-08T00:18:35-08:00
      DOI: 10.1093/conphys/cov065
      Issue No: Vol. 4, No. 1 (2016)
       
  • Intraspecific individual variation of temperature tolerance associated
           with oxygen demand in the European sea bass (Dicentrarchus labrax)

    • Authors: Ozolina, K; Shiels, H. A, Ollivier, H, Claireaux, G.
      Abstract: The European sea bass (Dicentrarchus labrax) is an economically important fish native to the Mediterranean and Northern Atlantic. Its complex life cycle involves many migrations through temperature gradients that affect the energetic demands of swimming. Previous studies have shown large intraspecific variation in swimming performance and temperature tolerance, which could include deleterious and advantageous traits under the evolutionary pressure of climate change. However, little is known of the underlying determinants of this individual variation. We investigated individual variation in temperature tolerance in 30 sea bass by exposing them to a warm temperature challenge test. The eight most temperature-tolerant and eight most temperature-sensitive fish were then studied further to determine maximal swimming speed (U CAT), aerobic scope and post-exercise oxygen consumption. Finally, ventricular contractility in each group was determined using isometric muscle preparations. The temperature-tolerant fish showed lower resting oxygen consumption rates, possessed larger hearts and initially recovered from exhaustive exercise faster than the temperature-sensitive fish. Thus, whole-animal temperature tolerance was associated with important performance traits. However, the temperature-tolerant fish also demonstrated poorer maximal swimming capacity (i.e. lower U CAT) than their temperature-sensitive counterparts, which may indicate a trade-off between temperature tolerance and swimming performance. Interestingly, the larger relative ventricular mass of the temperature-tolerant fish did not equate to greater ventricular contractility, suggesting that larger stroke volumes, rather than greater contractile strength, may be associated with thermal tolerance in this species.
      PubDate: 2016-01-08T00:18:35-08:00
      DOI: 10.1093/conphys/cov060
      Issue No: Vol. 4, No. 1 (2016)
       
  • Success stories and emerging themes in conservation physiology

    • Authors: Madliger, C. L; Cooke, S. J, Crespi, E. J, Funk, J. L, Hultine, K. R, Hunt, K. E, Rohr, J. R, Sinclair, B. J, Suski, C. D, Willis, C. K. R, Love, O. P.
      Abstract: The potential benefits of physiology for conservation are well established and include greater specificity of management techniques, determination of cause–effect relationships, increased sensitivity of health and disturbance monitoring and greater capacity for predicting future change. While descriptions of the specific avenues in which conservation and physiology can be integrated are readily available and important to the continuing expansion of the discipline of ‘conservation physiology’, to date there has been no assessment of how the field has specifically contributed to conservation success. However, the goal of conservation physiology is to foster conservation solutions and it is therefore important to assess whether physiological approaches contribute to downstream conservation outcomes and management decisions. Here, we present eight areas of conservation concern, ranging from chemical contamination to invasive species to ecotourism, where physiological approaches have led to beneficial changes in human behaviour, management or policy. We also discuss the shared characteristics of these successes, identifying emerging themes in the discipline. Specifically, we conclude that conservation physiology: (i) goes beyond documenting change to provide solutions; (ii) offers a diversity of physiological metrics beyond glucocorticoids (stress hormones); (iii) includes approaches that are transferable among species, locations and times; (iv) simultaneously allows for human use and benefits to wildlife; and (v) is characterized by successes that can be difficult to find in the primary literature. Overall, we submit that the field of conservation physiology has a strong foundation of achievements characterized by a diversity of conservation issues, taxa, physiological traits, ecosystem types and spatial scales. We hope that these concrete successes will encourage the continued evolution and use of physiological tools within conservation-based research and management plans.
      PubDate: 2016-01-05T00:13:04-08:00
      DOI: 10.1093/conphys/cov057
      Issue No: Vol. 4, No. 1 (2016)
       
 
 
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