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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  [339 journals]
  • Dive behaviour can predict metabolic expenditure in Steller sea lions

    • Authors: Goundie, E. T; Rosen, D. A. S, Trites, A. W.
      Abstract: Quantification of costs associated with foraging contributes to understanding the energetic impact that changes in prey availability have on the energy balance of an animal and the fitness of populations. However, estimating the costs of foraging is difficult for breath-hold divers, such as Steller sea lions, that feed underwater. We developed models parameterized with data from free-diving captive Steller sea lions to estimate the costs incurred by wild animals while foraging. We measured diving metabolic rate of trained sea lions performing four types of dives to 10 and 40 m in the open ocean and estimated the separate costs of different dive components: surface time; bottom time; and transiting to and from depth. We found that the sea lions' diving metabolic rates were higher while transiting (20.5 ± 13.0 ml O2 min–1 kg–1) than while swimming at depth (13.5 ± 4.1 ml O2 min–1 kg–1), and both were higher than metabolism at the surface (9.2 ± 1.6 ml O2 min–1 kg–1). These values were incorporated into an energetic model that accurately predicted oxygen consumption for dives only (within 9.5%) and dive cycles (within 7.7%), although it consistently overestimated costs by 5.9% for dives and 21.8% for dive cycles. Differences in the costs of individual components of dives also explained differences in the efficiency of different dive strategies. Single dives were energetically less costly than bout dives; however, sea lions were more efficient at replenishing oxygen stores after bout dives and could therefore spend a greater portion of their time foraging than when undertaking single dives. The metabolic rates we measured for the different behavioural components of diving can be applied to time–depth recordings from wild Steller sea lions to estimate the energy expended while foraging. In turn, this can be used to understand how changes in prey availability affect energy balance and the health of individuals in declining populations.
      PubDate: 2015-11-26T20:10:50-08:00
      DOI: 10.1093/conphys/cov052
      Issue No: Vol. 3, No. 1 (2015)
  • The role of thermal physiology in recent declines of birds in a
           biodiversity hotspot

    • Authors: Milne, R; Cunningham, S. J, Lee, A. T. K, Smit, B.
      Abstract: We investigated whether observed avian range contractions and population declines in the Fynbos biome of South Africa were mechanistically linked to recent climate warming. We aimed to determine whether there were correlations between preferred temperature envelope, or changes in temperature within species' ranges, and recent changes in range and population size, for 12 Fynbos-resident bird species, including six that are endemic to the biome. We then measured the physiological responses of each species at air temperatures ranging from 24 to 42°C to determine whether physiological thermal thresholds could provide a mechanistic explanation for observed population trends. Our data show that Fynbos-endemic species occupying the coolest regions experienced the greatest recent reductions in range and population size (>30% range reduction between 1991 and the present). In addition, species experiencing the largest increases in air temperature within their ranges showed the greatest declines. However, evidence for a physiological mechanistic link between warming and population declines was equivocal, with only the larger species showing low thermal thresholds for their body mass, compared with other birds globally. In addition, some species appear more vulnerable than others to air temperatures in their ranges above physiological thermal thresholds. Of these, the high-altitude specialist Cape rockjumper (Chaetops frenatus) seems most at risk from climate warming. This species showed: (i) the lowest threshold for increasing evaporative water loss at high temperatures; and (ii) population declines specifically in those regions of its range recording significant warming trends. Our findings suggest that caution must be taken when attributing causality explicitly to thermal stress, even when population trends are clearly correlated with rates of warming. Studies explicitly investigating the mechanisms underlying such correlations will be key to appropriate conservation planning.
      PubDate: 2015-11-15T23:00:57-08:00
      DOI: 10.1093/conphys/cov048
      Issue No: Vol. 3, No. 1 (2015)
  • Habitat-specific responses of leaf traits to soil water conditions in
           species from a novel alpine swamp meadow community

    • Authors: Li, H; Nicotra, A. B, Xu, D, Du, G.
      Abstract: Species originally from alpine wetland and alpine meadow communities now coexist in a novel ‘alpine swamp meadow’ community as a consequence of wetland drying in the eastern Tibetan Plateau. Considering the projected increase in the fluctuation of water supply from precipitation during the growing season in this area in the future, it is important to investigate the responses of the species that make up this new community to soil water availability. Using a transplant experimental design, we compared the response of leaf traits and growth to different water conditions for species grouped according to their original habitat of wetland or meadow. Twelve perennial herbaceous species, which form an alpine swamp meadow community in Maqu County in the eastern Tibetan Plateau, were used in this study and subjected to two water treatments, namely waterlogged and dry-down. Overall, significant differences in leaf production in response to soil water availability were found for these two groups, indicating strongly different effects of water availability on their growth. Furthermore, the meadow group had lower specific leaf area, leaf area and relative leaf water content, but thicker leaves than those of the wetland group, indicating significant habitat-specific differences in leaf morphology. Regarding physiological traits, the wetland group had significantly higher photosynthetic rates in inundated conditions, whereas for the meadow group the photosynthetic rate was greatest in cyclically dry conditions. Likewise, a similar pattern was observed for stomatal conductance; however, both groups achieved higher instantaneous water use efficiency during the dry-down treatment. The results of this study indicate that the composition of the alpine swamp meadow could be sensitive to changes in precipitation and might be changed substantially by future declines in water supply, as predicted by global climate change models for this region. This potential for compositional change of the community should be considered when management and conservation decisions are made.
      PubDate: 2015-11-11T23:14:09-08:00
      DOI: 10.1093/conphys/cov046
      Issue No: Vol. 3, No. 1 (2015)
  • Faecal corticosterone metabolite concentrations are not a good predictor
           of habitat suitability for common gartersnakes

    • Authors: Halliday, W. D; Gilmour, K. M, Blouin-Demers, G.
      Abstract: Measuring habitat suitability is important in conservation and in wildlife management. Measuring the abundance or presence–absence of a species in various habitats is not sufficient to measure habitat suitability because these metrics can be poor predictors of population success. Therefore, having some measure of population success is essential in assessing habitat suitability, but estimating population success is difficult. Identifying suitable proxies for population success could thus be beneficial. We examined whether faecal corticosterone metabolite (fCM) concentrations could be used as a proxy for habitat suitability in common gartersnakes (Thamnophis sirtalis). We conducted a validation study and confirmed that fCM concentrations indeed reflect circulating corticosterone concentrations. We estimated abundance, reproductive output and growth rate of gartersnakes in field and in forest habitat and we also measured fCM concentrations of gartersnakes from these same habitats. Common gartersnakes were more abundant and had higher reproductive outputs and higher growth rates in field habitat than in forest habitat, but fCM concentrations did not differ between the same two habitats. Our results suggest either that fCM concentrations are not a useful metric of habitat suitability in common gartersnakes or that the difference in suitability between the two habitats was too small to induce changes in fCM concentrations. Incorporating fitness metrics in estimates of habitat suitability is important, but these metrics of fitness have to be sensitive enough to vary between habitats.
      PubDate: 2015-10-20T18:19:23-07:00
      DOI: 10.1093/conphys/cov047
      Issue No: Vol. 3, No. 1 (2015)
  • Oxidative stress, activity behaviour and body mass in captive parrots

    • Authors: Larcombe, S. D; Tregaskes, C. A, Coffey, J, Stevenson, A. E, Alexander, L. G, Arnold, K. E.
      Abstract: Many parrot species are kept in captivity for conservation, but often show poor reproduction, health and survival. These traits are known to be influenced by oxidative stress, the imbalance between the production of reactive oxygen species (ROS) and ability of antioxidant defences to ameliorate ROS damage. In humans, oxidative stress is linked with obesity, lack of exercise and poor nutrition, all of which are common in captive animals. Here, we tested whether small parrots (budgerigars, Melopsittacus undulatus) maintained in typical pet cages and on ad libitum food varied in oxidative profile, behaviour and body mass. Importantly, as with many birds held in captivity, they did not have enough space to engage in extensive free flight. Four types of oxidative damage, single-stranded DNA breaks (low-pH comet assay), alkali-labile sites in DNA (high-pH comet assay), sensitivity of DNA to ROS (H2O2-treated comet assay) and malondialdehyde (a byproduct of lipid peroxidation), were uncorrelated with each other and with plasma concentrations of dietary antioxidants. Without strenuous exercise over 28 days in a relatively small cage, more naturally ‘active’ individuals had more single-stranded DNA breaks than sedentary birds. High body mass at the start or end of the experiment, coupled with substantial mass gain, were all associated with raised sensitivity of DNA to ROS. Thus, high body mass in these captive birds was associated with oxidative damage. These birds were not lacking dietary antioxidants, because final body mass was positively related to plasma levels of retinol, zeaxanthin and α-tocopherol. Individuals varied widely in activity levels, feeding behaviour, mass gain and oxidative profile despite standardized living conditions. DNA damage is often associated with poor immunocompetence, low fertility and faster ageing. Thus, we have candidate mechanisms for the limited lifespan and fecundity common to many birds kept for conservation purposes.
      PubDate: 2015-10-20T18:19:23-07:00
      DOI: 10.1093/conphys/cov045
      Issue No: Vol. 3, No. 1 (2015)
  • Evidence of low toxicity of oil sands process-affected water to birds
           invites re-evaluation of avian protection strategies

    • Authors: Beck, E. M; Smits, J. E. G, St Clair, C. C.
      Abstract: Exposure to water containing petroleum waste products can generate both overt and subtle toxicological responses in wildlife, including birds. Such exposure can occur in the tailings ponds of the mineable oil sands, which are located in Alberta, Canada, under a major continental flyway for waterfowl. Over the 40 year history of the industry, a few thousand bird deaths have been reported following contact with bitumen on the ponds, but a new monitoring programme demonstrated that many thousands of birds land annually without apparent harm. This new insight creates an urgent need for more information on the sublethal effects on birds from non-bitumen toxicants that occur in the water, including naphthenic acids, polycyclic aromatic hydrocarbons, heavy metals and salts. Ten studies have addressed the effects of oil sands process-affected water (OSPW), and none reported acute or substantial adverse health effects. Interpretive caution is warranted, however, because nine of the studies addressed reclaimed wetlands that received OSPW, not OSPW ponds per se, and differences between experimental and reference sites may have been reduced by shared sources of pollution in the surrounding air and water. Two studies examined eggs of birds nesting >100 km from the mine sites. Only one study exposed birds directly and repeatedly to OSPW and found no consistent differences between treated and control birds in blood-based health metrics. If it is true that aged forms of OSPW do not markedly affect the health of birds that land briefly on the ponds, then the extensiveness of current bird-deterrent programmes is unwarranted and could exert negative net environmental effects. More directed research on bird health is urgently needed, partly because birds that land on these ponds subsequently migrate to destinations throughout North America where they are consumed by both humans and wildlife predators.
      PubDate: 2015-10-03T05:04:15-07:00
      DOI: 10.1093/conphys/cov038
      Issue No: Vol. 3, No. 1 (2015)
  • Physiological predictors of long-term survival in juvenile Steller sea
           lions (Eumetopias jubatus)

    • Authors: Shuert, C; Mellish, J, Horning, M.
      Abstract: This study builds on a continued effort to document potential long-term research impacts on the individual, as well as to identify potential markers of survival for use in a field framework. The Transient Juvenile Steller sea lion (TJ) project was developed as a novel framework to gain access to wild individuals. We used three analyses to evaluate and predict long-term survival in temporarily captive sea lions (n = 45) through Cormack–Jolly–Seber open population modelling techniques. The first analysis investigated survival in relation to the observed responses to handling stress through changes in six principal blood parameters over the duration of captivity. The second analysis evaluated survival compared with body condition and mass at entry and exit from captivity. Finally, the third analysis sought to evaluate the efficacy of single-point sampling to project similar survival trends for use in field sampling operations. Results from a priori models ranked through Akaike information criterion model selection methods indicated that mass gains (4.2 ± 12%) over captivity and increases in leucocytes (WBC, 1.01 ± 3.54 x 103/mm3) resulted in a higher average survival rate (>3 years). Minor support was identified for the single-point measures of exit mass and entry WBC. A higher exit mass predicted a higher survival rate, whereas a higher WBC predicted a lower survival rate. While changes in mass and WBC appear to be the best predictors of survival when measured as a change over time, single-point sampling may still be an effective way to improve estimates of population health.
      PubDate: 2015-09-30T18:45:07-07:00
      DOI: 10.1093/conphys/cov043
      Issue No: Vol. 3, No. 1 (2015)
  • High survivorship after catch-and-release fishing suggests physiological
           resilience in the endothermic shortfin mako shark (Isurus oxyrinchus)

    • Authors: French, R. P; Lyle, J, Tracey, S, Currie, S, Semmens, J. M.
      Abstract: The shortfin mako shark (Isurus oxyrinchus) is a species commonly targeted by commercial and recreational anglers in many parts of the developed world. In Australia, the species is targeted by recreational anglers only, under the assumption that most of the sharks are released and populations remain minimally impacted. If released sharks do not survive, the current management strategy will need to be revised. Shortfin mako sharks are commonly subjected to lengthy angling events; however, their endothermic physiology may provide an advantage over ectothermic fishes when recovering from exercise. This study assessed the post-release survival of recreationally caught shortfin mako sharks using Survivorship Pop-up Archival Transmitting (sPAT) tags and examined physiological indicators of capture stress from blood samples as well as any injuries that may be caused by hook selection. Survival estimates were based on 30 shortfin mako sharks captured off the south-eastern coast of Australia. Three mortalities were observed over the duration of the study, yielding an overall survival rate of 90%. All mortalities occurred in sharks angled for
      PubDate: 2015-09-30T18:45:07-07:00
      DOI: 10.1093/conphys/cov044
      Issue No: Vol. 3, No. 1 (2015)
  • Winter temperatures decrease swimming performance and limit distributions
           of tropical damselfishes

    • Authors: Johansen, J. L; Steffensen, J. F, Jones, G. P.
      Abstract: Coral reefs within 10° of the equator generally experience ≤3°C seasonal variation in water temperature. Ectotherms that have evolved in these conditions are therefore expected to exhibit narrow thermal optima and be very sensitive to the greater thermal variability (>6°C) experienced at higher latitudes (≥10°N/S). The impact of increased thermal variability on the fitness and distribution of thermally sensitive reef ectotherms is currently unknown. Here, we examine site-attached planktivorous coral reef damselfishes that rely on their physiological capacity to swim and forage in the water column year round. We focus on 10 species spanning four evolutionarily distinct genera from a region of the Great Barrier Reef that experiences ≥6°C difference between seasons. Four ecologically important indicators showed reduced performance during the winter low (23°C) compared with the summer peak (29°C), with effect sizes varying among species and genera, as follows: (i) the energy available for activity (aerobic scope) was reduced by 35–45% in five species and three genera; (ii) the energetically most efficient swimming speed was reduced by 17% across all species; and (iii) the maximal critical swimming speed and (iv) the gait transition speed (the swimming mode predominantly used for foraging) were reduced by 16–42% in six species spanning all four genera. Comparisons with field surveys within and across latitudes showed that species-specific distributions were strongly correlated with these performance indicators. Species occupy habitats where they can swim faster than prevailing habitat currents year round, and >95% of individuals were observed only in habitats where the gait transition speed can be maintained at or above habitat currents. Thermal fluctuation at higher latitudes appears to reduce performance as well as the possible distribution of species and genera within and among coral reef habitats. Ultimately, thermal variability across latitudes may progressively cause sublethal changes to species performance and lead to a contraction of biogeographical range.
      PubDate: 2015-09-18T00:51:54-07:00
      DOI: 10.1093/conphys/cov039
      Issue No: Vol. 3, No. 1 (2015)
  • Fish-protection devices at unscreened water diversions can reduce
           entrainment: evidence from behavioural laboratory investigations

    • Authors: Poletto, J. B; Cocherell, D. E, Mussen, T. D, Ercan, A, Bandeh, H, Kavvas, M. L, Cech, J. J, Fangue, N. A.
      Abstract: Diversion (i.e. extraction) of water from rivers and estuaries can potentially affect native wildlife populations if operation is not carefully managed. For example, open, unmodified water diversions can act as a source of injury or mortality to resident or migratory fishes from entrainment and impingement, and can cause habitat degradation and fragmentation. Fish-protection devices, such as exclusion screens, louvres or sensory deterrents, can physically or behaviourally deter fish from approaching or being entrained into water diversions. However, empirical assessment of their efficacy is often lacking or is investigated only for particular economically or culturally important fishes, such as salmonids. The Southern population of anadromous green sturgeon (Acipenser medirostris) is listed as threatened in California, and there is a high density of water diversions located within their native range (the Sacramento–San Joaquin watershed). Coupled with their unique physiology and behaviour compared with many other fishes native to California, the green sturgeon is susceptible to entrainment into diversions and is an ideal species with which to study the efficacy of mitigation techniques. Therefore, we investigated juvenile green sturgeon (188–202 days post-hatch) in the presence of several fish-protection devices to assess behaviour and entrainment risk. Using a large experimental flume (~500 kl), we found that compared with an open diversion pipe (control), the addition of a trash-rack box, louvre box, or perforated cylinder on the pipe inlet all significantly reduced the proportion of fish that were entrained through the pipe (P = 0.03, P = 0.028, and P = 0.028, respectively). Likewise, these devices decreased entrainment risk during a single movement past the pipe by between 60 and 96%. These fish-protection devices should decrease the risk of fish entrainment during water-diversion activities.
      PubDate: 2015-09-15T22:16:59-07:00
      DOI: 10.1093/conphys/cov040
      Issue No: Vol. 3, No. 1 (2015)
  • Optimization, validation and efficacy of the phytohaemagglutinin
           inflammation assay for use in ecoimmunological studies of amphibians

    • Authors: Clulow, S; Harris, M, Mahony, M. J.
      Abstract: The global amphibian biodiversity crisis is driven by disease, habitat destruction and drastically altered ecosystems. It has given rise to an unprecedented need to understand the link between rapidly changing environments, immunocompetence and wildlife health (the nascent field of ecoimmunology). Increasing our knowledge of the ecoimmunology of amphibians necessitates the development of reliable, field-applicable methods of assessing immunocompetence in non-model species. The phytohaemagglutinin (PHA) inflammation assay uses a lectin to elicit localized inflammation that reflects an organism's capacity to mount an immune response. Although extensively used in birds to assess responses to environmental change, stress and disease, its application in amphibians has been extremely limited. We developed, validated and optimized a practical and effective phytohaemagglutinin inflammation assay in phylogenetically distant amphibians and demonstrated its suitability for use in a wide range of ecoimmunological studies. The protocol was effective for all species tested and worked equally well for both sexes and for adult and sub-adult animals. We determined that using set-force-measuring instruments resulted in a ‘compression effect’ that countered the inflammatory response, reinforcing the need for internal controls. We developed a novel method to determine peak response times more accurately and thereby improve assay sensitivity. Histological validation demonstrated considerable interspecies variation in the robustness of amphibian immune defences. Importantly, we applied the assay to a real-world scenario of varying environmental conditions and proved that the assay effectively detected differences in immune fitness between groups of animals exposed to ecologically meaningful levels of density stress. This provided strong evidence that one cost of metamorphic plasticity responses by tadpoles to increasing density is a reduction in post-metamorphic immune fitness and that metamorphosis does not prevent phenotypic carry-over of larval stress to the adult phenotype. This assay provides an effective tool for understanding the role of global environmental change in the amphibian extinction crisis.
      PubDate: 2015-09-12T03:02:23-07:00
      DOI: 10.1093/conphys/cov042
      Issue No: Vol. 3, No. 1 (2015)
  • Effects of human disturbance on cave-nesting seabirds: the case of the
           storm petrel

    • Authors: Soldatini, C; Albores-Barajas, Y. V, Tagliavia, M, Massa, B, Fusani, L, Canoine, V.
      Abstract: Human disturbance is an important stress factor with potentially strong impact on breeding activity in animals. The consequences can be extinction of the breeding population, because disturbed animals might desert their breeding area and find no suitable substitute area. In this study, we investigated the effects of anthropogenic disturbance on a breeding population of Mediterranean storm petrels. Seabirds are increasingly used as bio-indicators for sea environmental parameters, because they are very sensitive to changing conditions. Burrowing or cave-nesting species may be particularly susceptible to human disturbance because their direct contact with humans is usually minimal or absent. First, we compared two different populations (exposed or not exposed to human disturbance) for their individual stress response to a standardized stressor (handling and keeping in a cloth bag). Second, we compared the two sub-colonies for their population-level stress response. Third, we tested experimentally whether sub-colonies of storm petrels exposed to tourism have physiological adaptations to anthropogenic disturbances. Our results indicate that storm petrels may be habituated to moderate disturbance associated with boat traffic close to the colony.
      PubDate: 2015-09-10T18:10:25-07:00
      DOI: 10.1093/conphys/cov041
      Issue No: Vol. 3, No. 1 (2015)
  • Establishment of reference intervals for plasma protein electrophoresis in
           Indo-Pacific green sea turtles, Chelonia mydas

    • Authors: Flint, M; Matthews, B. J, Limpus, C. J, Mills, P. C.
      Abstract: Biochemical and haematological parameters are increasingly used to diagnose disease in green sea turtles. Specific clinical pathology tools, such as plasma protein electrophoresis analysis, are now being used more frequently to improve our ability to diagnose disease in the live animal. Plasma protein reference intervals were calculated from 55 clinically healthy green sea turtles using pulsed field electrophoresis to determine pre-albumin, albumin, α-, β- and -globulin concentrations. The estimated reference intervals were then compared with data profiles from clinically unhealthy turtles admitted to a local wildlife hospital to assess the validity of the derived intervals and identify the clinically useful plasma protein fractions. Eighty-six per cent {19 of 22 [95% confidence interval (CI) 65–97]} of clinically unhealthy turtles had values outside the derived reference intervals, including the following: total protein [six of 22 turtles or 27% (95% CI 11–50%)], pre-albumin [two of five, 40% (95% CI 5–85%)], albumin [13 of 22, 59% (95% CI 36–79%)], total albumin [13 of 22, 59% (95% CI 36–79%)], α- [10 of 22, 45% (95% CI 24–68%)], β- [two of 10, 20% (95% CI 3–56%)], - [one of 10, 10% (95% CI 0.3–45%)] and β–-globulin [one of 12, 8% (95% CI 0.2–38%)] and total globulin [five of 22, 23% (8–45%)]. Plasma protein electrophoresis shows promise as an accurate adjunct tool to identify a disease state in marine turtles. This study presents the first reference interval for plasma protein electrophoresis in the Indo-Pacific green sea turtle.
      PubDate: 2015-09-02T00:22:47-07:00
      DOI: 10.1093/conphys/cov037
      Issue No: Vol. 3, No. 1 (2015)
  • Local site variation in stopover physiology of migrating songbirds near
           the south shore of Lake Ontario is linked to fruit availability and

    • Authors: Smith, S. B; Miller, A. C, Merchant, C. R, Sankoh, A. F.
      Abstract: Birds that migrate long distances between breeding and wintering grounds are challenged to find adequate stopover sites that can provide a high-quality source of nutrition in order to refuel quickly and continue on their migratory journeys. Wild fruits are a well-documented component in the diets of many passerines during autumn migration. Thus, fruit availability and the proliferation of shrubs that bear low-quality fruits at important stopover sites may dictate the quality of food resources available for refuelling birds and present a conservation concern. We profiled plasma metabolites of two migratory passerine species at two different stopover sites near the south shore of Lake Ontario during the peak of autumn migration. We also measured diversity, availability and nutritional quality of fruits present at these sites. Site explained most of the variation in plasma triglyceride for both bird species, but was less important than other confounding variables for explaining concentrations of plasma β-hydroxybutyrate and plasma uric acid concentrations. Site differences in fat deposition, as indicated by plasma triglyceride, may in part be explained by the large differences in diversity and availability of high-quality fruits between the two sites. Our results suggest that abundant, lipid-rich native fruits with high-energy density are associated with increased fat deposition during autumn stopovers for some species, although other factors, such as proximity to the Lake Ontario shoreline and the opportunities to refuel in the surrounding landscape, are likely to play a role in stopover site use by birds. It is possible that local site characteristics that influence growing conditions may impact the quality of fruits produced by a plant species, altering the availability of critical nutrients for avian consumers.
      PubDate: 2015-08-13T00:12:58-07:00
      DOI: 10.1093/conphys/cov036
      Issue No: Vol. 3, No. 1 (2015)
  • Toward a mechanistic understanding of animal migration: incorporating
           physiological measurements in the study of animal movement

    • Authors: Jachowski, D. S; Singh, N. J.
      Abstract: Movements are a consequence of an individual's motion and navigational capacity, internal state variables and the influence of external environmental conditions. Although substantial advancements have been made in methods of measuring and quantifying variation in motion capacity, navigational capacity and external environmental parameters in recent decades, the role of internal state in animal migration (and in movement in general) is comparatively little studied. Recent studies of animal movement in the wild illustrate how direct physiological measurements can improve our understanding of the mechanisms underlying movement decisions. In this review, we synthesize and provide examples of how recent technical advances in the physiology-related fields of energetics, nutrition, endocrinology, immunology and ecotoxicology provide opportunities for direct measurements of physiological state in the study of animal movement. We then propose a framework for practitioners to enable better integration of studies of physiological state into animal movement ecology by assessing the mechanistic role played by physiology as both a driver and a modulator of movement. Finally, we highlight the current limitations and research priorities for better integration of direct measurements of animal physiological state into the study of animal movement.
      PubDate: 2015-08-05T01:15:33-07:00
      DOI: 10.1093/conphys/cov035
      Issue No: Vol. 3, No. 1 (2015)
  • Ocean acidification exerts negative effects during warming conditions in a
           developing Antarctic fish

    • Authors: Flynn, E. E; Bjelde, B. E, Miller, N. A, Todgham, A. E.
      Abstract: Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (~10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [–1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only in the presence of an increased temperature. In addition to reduced hatching success, alterations in development and metabolism due to ocean warming and acidification could have negative ecological consequences owing to changes in phenology (i.e. early hatching) in the highly seasonal Antarctic ecosystem.
      PubDate: 2015-07-30T00:00:42-07:00
      DOI: 10.1093/conphys/cov033
      Issue No: Vol. 3, No. 1 (2015)
  • Blood gases, biochemistry and haematology of Galapagos marine iguanas
           (Amblyrhynchus cristatus)

    • Authors: Lewbart, G. A; Hirschfeld, M, Brothers, J. R, Munoz-Perez, J. P, Denkinger, J, Vinueza, L, Garcia, J, Lohmann, K. J.
      Abstract: The marine iguana, Amblyrhynchus cristatus, is an iconic lizard endemic to the Galápagos Islands of Ecuador, but surprisingly little information exists on baseline health parameters for this species. We analysed blood samples drawn from 35 marine iguanas captured at three locations on San Cristóbal Island. A portable blood analyser (iSTAT) was used to obtain near-immediate field results for pH, lactate, partial pressure of O2, partial pressure of CO2, bicarbonate (HCO3 –), percentage O2 saturation, haematocrit, haemoglobin, sodium, potassium, ionized calcium and glucose. Parameter values affected by temperature were auto-corrected by the iSTAT. Standard laboratory haematology techniques were employed for differential white blood cell counts and haematocrit determination; resulting values were also compared with the haematocrit values generated by the iSTAT. Body temperature, heart rate, respiratory rate and body measurements were also recorded. Body length was positively correlated with several blood chemistry values (HCO3 – and glucose) and two haematology parameters (haemoglobin and manually determined haematocrit). A notable finding was the unusually high blood sodium level; the mean value of 178 mg/dl is among the highest known for any reptile. This value is likely to be a conservative estimate because some samples exceeded the maximal value the iSTAT can detect. For haematocrit determination, the iSTAT blood analyser yielded results significantly lower than those obtained with high-speed centrifugation. The values reported in this study provide baseline data that may be useful in comparisons among populations and in detecting changes in health status among marine iguanas affected by natural disturbances or anthropogenic threats. The findings might also be helpful in future efforts to demonstrate associations between specific biochemical parameters and disease.
      PubDate: 2015-07-24T23:26:31-07:00
      DOI: 10.1093/conphys/cov034
      Issue No: Vol. 3, No. 1 (2015)
  • Comparative immune responses of corals to stressors associated with
           offshore reef-based tourist platforms

    • Authors: van de Water, J. A. J. M; Lamb, J. B, van Oppen, M. J. H, Willis, B. L, Bourne, D. G.
      Abstract: Unravelling the contributions of local anthropogenic and seasonal environmental factors in suppressing the coral immune system is important for prioritizing management actions at reefs exposed to high levels of human activities. Here, we monitor health of the model coral Acropora millepora adjacent to a high-use and an unused reef-based tourist platform, plus a nearby control site without a platform, over 7 months spanning a typical austral summer. Comparisons of temporal patterns in a range of biochemical and genetic immune parameters (Toll-like receptor signalling pathway, lectin–complement system, prophenoloxidase-activating system and green fluorescent protein-like proteins) among healthy, injured and diseased corals revealed that corals exhibit a diverse array of immune responses to environmental and anthropogenic stressors. In healthy corals at the control site, expression of genes involved in the Toll-like receptor signalling pathway (MAPK p38, MEKK1, cFos and ATF4/5) and complement system (C3 and Bf) was modulated by seasonal environmental factors in summer months. Corals at reef platform sites experienced additional stressors over the summer, as evidenced by increased expression of various immune genes, including MAPK p38 and MEKK1. Despite increased expression of immune genes, signs of white syndromes were detected in 31% of study corals near tourist platforms in the warmest summer month. Evidence that colonies developing disease showed reduced expression of genes involved in the complement pathway prior to disease onset suggests that their immune systems may have been compromised. Responses to disease and physical damage primarily involved the melanization cascade and GFP-like proteins, and appeared to be sufficient for recovery when summer heat stress subsided. Overall, seasonal and anthropogenic factors may have interacted synergistically to overwhelm the immune systems of corals near reef platforms, leading to increased disease prevalence in summer at these sites.
      PubDate: 2015-07-24T23:26:31-07:00
      DOI: 10.1093/conphys/cov032
      Issue No: Vol. 3, No. 1 (2015)
  • Manipulating glucocorticoids in wild animals: basic and applied

    • Authors: Sopinka, N. M; Patterson, L. D, Redfern, J. C, Pleizier, N. K, Belanger, C. B, Midwood, J. D, Crossin, G. T, Cooke, S. J.
      Abstract: One of the most comprehensively studied responses to stressors in vertebrates is the endogenous production and regulation of glucocorticoids (GCs). Extensive laboratory research using experimental elevation of GCs in model species is instrumental in learning about stressor-induced physiological and behavioural mechanisms; however, such studies fail to inform our understanding of ecological and evolutionary processes in the wild. We reviewed emerging research that has used GC manipulations in wild vertebrates to assess GC-mediated effects on survival, physiology, behaviour, reproduction and offspring quality. Within and across taxa, exogenous manipulation of GCs increased, decreased or had no effect on traits examined in the reviewed studies. The notable diversity in responses to GC manipulation could be associated with variation in experimental methods, inherent differences among species, morphs, sexes and age classes, and the ecological conditions in which responses were measured. In their current form, results from experimental studies may be applied to animal conservation on a case-by-case basis in contexts such as threshold-based management. We discuss ways to integrate mechanistic explanations for changes in animal abundance in altered environments with functional applications that inform conservation practitioners of which species and traits may be most responsive to environmental change or human disturbance. Experimental GC manipulation holds promise for determining mechanisms underlying fitness impairment and population declines. Future work in this area should examine multiple life-history traits, with consideration of individual variation and, most importantly, validation of GC manipulations within naturally occurring and physiologically relevant ranges.
      PubDate: 2015-07-24T01:57:00-07:00
      DOI: 10.1093/conphys/cov031
      Issue No: Vol. 3, No. 1 (2015)
  • Long-term changes in food availability mediate the effects of temperature
           on growth, development and survival in striped marsh frog larvae:
           implications for captive breeding programmes

    • Authors: Courtney Jones, S. K; Munn, A. J, Penman, T. D, Byrne, P. G.
      Abstract: Food availability and temperature are known to trigger phenotypic change, but the interactive effects between these factors are only beginning to be considered. The aim of this study was to examine the independent and interactive effects of long-term stochastic food availability and water temperature on larval survivorship, growth and development of the striped marsh frog, Limnodynastes peronii. Larval L. peronii were reared in conditions of either constant or stochastic food availability and in water at three different temperatures (18, 22 and 26°C), and effects on survival, growth and development were quantified. Over the experimental period, larval growth rate was highest and survivorship lowest at the warmest temperature. However, changes in food availability mediated the effects of temperature, with slower larval growth and higher survivorship in stochastic food availability treatments. Tadpoles in the stochastic food availability treatments did not reach metamorphosis during the experimental period, suggesting that developmental stasis may have been induced by food restriction. Overall, these results demonstrate that changes in food availability alter the effects of water temperature on survival, growth and development. From an applied perspective, understanding how environmental factors interact to cause phenotypic change may assist with amphibian conservation by improving the number of tadpoles generated in captive breeding programmes.
      PubDate: 2015-07-08T18:32:55-07:00
      DOI: 10.1093/conphys/cov029
      Issue No: Vol. 3, No. 1 (2015)
  • Towards a better monitoring of seed ageing under ex situ seed conservation

    • Authors: Fu, Y.-B; Ahmed, Z, Diederichsen, A.
      Abstract: Long-term conservation of 7.4 million ex situ seed accessions held in agricultural genebanks and botanic gardens worldwide is a challenging mission for human food security and ecosystem services. Recent advances in seed biology and genomics may have opened new opportunities for effective management of seed germplasm under long-term storage. Here, we review the current development of tools for assessing seed ageing and research advances in seed biology and genomics, with a focus on exploring their potential as better tools for monitoring of seed ageing. Seed ageing is found to be associated with the changes reflected in reactive oxygen species and mitochondria-triggered programmed cell deaths, expression of antioxidative genes and DNA and protein repair genes, chromosome telomere lengths, epigenetic regulation of related genes (microRNA and methylation) and altered organelle and nuclear genomes. Among these changes, the signals from mitochondrial and nuclear genomes may show the most promise for use in the development of tools to predict seed ageing. Non-destructive and non-invasive analyses of stored seeds through calorimetry or imaging techniques are also promising. It is clear that research into developing advanced tools for monitoring seed ageing to supplement traditional germination tests will be fruitful for effective conservation of ex situ seed germplasm.
      PubDate: 2015-07-02T22:18:16-07:00
      DOI: 10.1093/conphys/cov026
      Issue No: Vol. 3, No. 1 (2015)
  • Variation in spawning time promotes genetic variability in population
           responses to environmental change in a marine fish

    • Authors: Oomen, R. A; Hutchings, J. A.
      Abstract: The level of phenotypic plasticity displayed within a population (i.e. the slope of the reaction norm) reflects the short-term response of a population to environmental change, while variation in reaction norm slopes among populations reflects spatial variation in these responses. Thus far, studies of thermal reaction norm variation have focused on geographically driven adaptation among different latitudes, altitudes or habitats. Yet, thermal variability is a function of both space and time. For organisms that reproduce at different times of year, such variation has the potential to promote adaptive variability in thermal responses for critical early life stages. Using common-garden experiments, we examined the spatial scale of genetic variation in thermal plasticity for early life-history traits among five populations of endangered Atlantic cod (Gadus morhua) that spawn at different times of year. Patterns of plasticity for larval growth and survival suggest that population responses to climate change will differ substantially, with increasing water temperatures posing a considerably greater threat to autumn-spawning cod than to those that spawn in winter or spring. Adaptation to seasonal cooling or warming experienced during the larval stage is suggested as a possible cause. Furthermore, populations that experience relatively cold temperatures during early life might be more sensitive to changes in temperature. Substantial divergence in adaptive traits was evident at a smaller spatial scale than has previously been shown for a marine fish with no apparent physical barriers to gene flow (~200 km). Our findings highlight the need to consider the impact of intraspecific variation in reproductive timing on thermal adaptation when forecasting the effects of climate change on animal populations.
      PubDate: 2015-07-02T22:18:16-07:00
      DOI: 10.1093/conphys/cov027
      Issue No: Vol. 3, No. 1 (2015)
  • Stress and body condition are associated with climate and demography in
           Asian elephants

    • Authors: Mumby, H. S; Mar, K. U, Thitaram, C, Courtiol, A, Towiboon, P, Min-Oo, Z, Htut-Aung, Y, Brown, J. L, Lummaa, V.
      Abstract: Establishing links between ecological variation, physiological markers of stress and demography is crucial for understanding how and why changes in environmental conditions affect population dynamics, and may also play a key role for conservation efforts of endangered species. However, detailed longitudinal studies of long-lived species are rarely available. We test how two markers of stress and body condition vary through the year and are associated with climatic conditions and large-scale mortality and fertility variation in the world's largest semi-captive population of Asian elephants employed in the timber industry in Myanmar. Glucocorticoid metabolites (used as a proxy for stress levels in 75 elephants) and body weight (used as a proxy for condition in 116 elephants) were monitored monthly across a typical monsoon cycle and compared with birth and death patterns of the entire elephant population over half a century (n = 2350). Our results show seasonal variation in both markers of stress and condition. In addition, this variation is correlated with population-level demographic variables. Weight is inversely correlated with population mortality rates 1 month later, and glucocorticoid metabolites are negatively associated with birth rates. Weight shows a highly positive correlation with rainfall 1 month earlier. Determining the factors associated with demography may be key to species conservation by providing information about the correlates of mortality and fertility patterns. The unsustainability of the studied captive population has meant that wild elephants have been captured and tamed for work. By elucidating the correlates of demography in captive elephants, our results offer management solutions that could reduce the pressure on the wild elephant population in Myanmar.
      PubDate: 2015-06-30T01:23:45-07:00
      DOI: 10.1093/conphys/cov030
      Issue No: Vol. 3, No. 1 (2015)
  • Leucocyte profiles of Arctic marine birds: correlates of migration and
           breeding phenology

    • Authors: Mallory, M. L; Little, C. M, Boyd, E. S, Ballard, J, Elliott, K. H, Gilchrist, H. G, Hipfner, J. M, Petersen, A, Shutler, D.
      Abstract: Most Arctic marine birds are migratory, wintering south of the limit of annual pack ice and returning north each year for the physiologically stressful breeding season. The Arctic environment is changing rapidly due to global warming and anthropogenic activities, which may influence the timing of breeding in relation to arrival times following migration, as well as providing additional stressors (e.g. disturbance from ships) to which birds may respond. During stressful parts of their annual cycle, such as breeding, birds may reallocate resources so that they have increased heterophil-to-lymphocyte ratios in their white blood cell (leucocyte) profiles. We analysed leucocyte profiles of nine species of marine birds to establish reference ranges for these species in advance of future Arctic change. Leucocyte profiles tended to cluster among taxonomic groups across studies, suggesting that reference values for a particular group can be established, and within species there was evidence that birds from colonies that had to migrate farther had higher heterophil-to-lymphocyte ratios during incubation than those that did not have to travel as far, particularly for species with high wing loading.
      PubDate: 2015-06-26T21:52:02-07:00
      DOI: 10.1093/conphys/cov028
      Issue No: Vol. 3, No. 1 (2015)
  • Key metabolites in tissue extracts of Elliptio complanata identified using
           1H nuclear magnetic resonance spectroscopy

    • Authors: Hurley-Sanders, J. L; Levine, J. F, Nelson, S. A. C, Law, J. M, Showers, W. J, Stoskopf, M. K.
      Abstract: We used 1H nuclear magnetic resonance spectroscopy to describe key metabolites of the polar metabolome of the freshwater mussel, Elliptio complanata. Principal components analysis documented variability across tissue types and river of origin in mussels collected from two rivers in North Carolina (USA). Muscle, digestive gland, mantle and gill tissues yielded identifiable but overlapping metabolic profiles. Variation in digestive gland metabolic profiles between the two mussel collection sites was characterized by differences in mono- and disaccharides. Variation in mantle tissue metabolomes appeared to be associated with sex. Nuclear magnetic resonance spectroscopy is a sensitive means to detect metabolites in the tissues of E. complanata and holds promise as a tool for the investigation of freshwater mussel health and physiology.
      PubDate: 2015-06-20T03:13:07-07:00
      DOI: 10.1093/conphys/cov023
      Issue No: Vol. 3, No. 1 (2015)
  • Condition index monitoring supports conservation priorities for the
           protection of threatened grass-finch populations

    • Authors: Maute, K; French, K, Legge, S, Astheimer, L, Garnett, S.
      Abstract: Conservation agencies are often faced with the difficult task of prioritizing what recovery actions receive support. With the number of species under threat of decline growing globally, research that informs conservation priorities is greatly needed. The relative vulnerability of cryptic or nomadic species is often uncertain, because populations are difficult to monitor and local populations often seem stable in the short term. This uncertainty can lead to inaction when populations are in need of protection. We tested the feasibility of using differences in condition indices as an indication of population vulnerability to decline for related threatened Australian finch sub-species. The Gouldian finch represents a relatively well-studied endangered species, which has a seasonal and site-specific pattern of condition index variation that differs from the closely related non-declining long-tailed finch. We used Gouldian and long-tailed finch condition variation as a model to compare with lesser studied, threatened star and black-throated finches. We compared body condition (fat and muscle scores), haematocrit and stress levels (corticosterone) among populations, seasons and years to determine whether lesser studied finch populations matched the model of an endangered species or a non-declining species. While vulnerable finch populations often had lower muscle and higher fat and corticosterone concentrations during moult (seasonal pattern similar to Gouldian finches), haematocrit values did not differ among populations in a predictable way. Star and black-throated finch populations, which were predicted to be vulnerable to decline, showed evidence of poor condition during moult, supporting their status as vulnerable. Our findings highlight how measures of condition can provide insight into the relative vulnerability of animal and plant populations to decline and will allow the prioritization of efforts towards the populations most likely to be in jeopardy of extinction.
      PubDate: 2015-06-16T01:16:36-07:00
      DOI: 10.1093/conphys/cov025
      Issue No: Vol. 3, No. 1 (2015)
  • Oxidative stress predicts long-term resight probability and reproductive
           success in Scopoli's shearwater (Calonectris diomedea)

    • Authors: Costantini, D; Dell'Omo, G.
      Abstract: A major challenge in conservation physiology is to find out biomarkers that reliably reflect individual variation in wear and tear. Recent work has suggested that biomarkers of oxidative stress may provide an additional tool to assess the health state of individuals and to predict fitness perspectives. In this study, we assessed whether three biomarkers of plasma oxidative status predicted the following factors: (i) the resight probability as breeder in the next seasons; and (ii) the cumulative reproductive output over multiple years in Scopoli’s shearwaters (Calonectris diomedea) using a 7 year individual-based data set. Our results show that shearwaters having higher levels of a marker of oxidative damage (reactive oxygen metabolites) in 2008 had a lower resight probability in the next years and a lower number of chicks raised from 2008 to 2014. In contrast, two biomarkers of antioxidant defences (non-enzymatic antioxidant capacity of plasma and thiols) did not have any predictive value. Increased concentrations of plasma reactive oxygen metabolites, together with the significant individual repeatability over time in this metric of oxidative stress found in numerous studies, suggest that this metric might serve as a blood-derived biomarker for health and fitness perspectives in birds and, possibly, also in other taxa.
      PubDate: 2015-06-02T01:16:36-07:00
      DOI: 10.1093/conphys/cov024
      Issue No: Vol. 3, No. 1 (2015)
  • Reproductive and immune effects of chronic corticosterone treatment in
           male White's treefrogs, Litoria caerulea

    • Authors: Kaiser, K; Devito, J, Jones, C. G, Marentes, A, Perez, R, Umeh, L, Weickum, R. M, McGovern, K. E, Wilson, E. H, Saltzman, W.
      Abstract: Amphibian populations are declining globally. The potential contribution of glucocorticoid hormones to these declines has received little attention, but chronic elevation of glucocorticoids has been linked to a suite of negative outcomes across vertebrate taxa. Recently, chronic environmental stress has been associated with precipitous declines in sperm count and sperm viability in White’s treefrogs (Litoria caerulea), but the mechanism remains unknown. In order to determine whether corticosterone is responsible for suppressing reproductive and immune function in this species, we elevated circulating concentrations of corticosterone in 10 male captive-bred frogs via transdermal application for 7 days. We compared sperm count, sperm viability, splenic cell count and circulating leucocyte counts in corticosterone-treated frogs with those in untreated control frogs. Chronic application of exogenous corticosterone led to supraphysiological circulating concentrations of corticosterone, but had no effect on sperm count or viability. However, corticosterone-treated frogs demonstrated a significant decrease in circulating eosinophils, which are immune cells implicated in fighting a variety of pathogens, including extracellular parasites. These findings suggest that although chronic elevation of circulating corticosterone is not necessarily associated with reproductive suppression in this species, it may cause immunosuppression. Thus, chronic glucocorticoid elevations in amphibians might enhance susceptibility to infection with pathogens and parasites, and their potential contributions to global population declines warrant further study.
      PubDate: 2015-05-25T18:37:22-07:00
      DOI: 10.1093/conphys/cov022
      Issue No: Vol. 3, No. 1 (2015)
  • The degradation of proteins in pinniped skeletal muscle: viability of
           post-mortem tissue in physiological research

    • Authors: Moore, C. D; Fahlman, A, Crocker, D. E, Robbins, K. A, Trumble, S. J.
      Abstract: As marine divers, pinnipeds have a high capacity for exercise at depth while holding their breath. With finite access to oxygen, these species need to be capable of extended aerobic exercise and conservation of energy. Pinnipeds must deal with common physiological hurdles, such as hypoxia, exhaustion and acidosis, that are common to all exercising mammals. The physiological mechanisms in marine mammals used for managing oxygen and carbon dioxide have sparked much research, but access to animals and tissues is difficult and requires permits. Deceased animals that are either bycaught or stranded provide one potential source for tissues, but the validity of biochemical data from post-mortem samples has not been rigorously assessed. Tissues collected from stranded diving mammals may be a crucial source to add to our limited knowledge on the physiology of some of these animals and important to the conservation and management of these species. We aim to determine the reliability of biochemical assays derived from post-mortem tissue and to promote the immediate sampling of stranded animals for the purpose of physiological research. In this study, we mapped the temporal degradation of muscle enzymes from biopsied Northern elephant seals (Mirounga angustirostris) and highlight recommendations for storage protocols for the best preservation of tissue. We also compared the enzymatic activity of different muscle groups (pectoral and latissimus dorsi) in relation to locomotion and measured the effects of four freeze–thaw cycles on muscle tissue enzyme function. Results indicate that enzymatic activity fluctuates greatly, especially with varying storage temperature, storage time, species and muscle group being assayed. In contrast, proteins, such as myoglobin, remain relatively continuous in their increase at 4°C for 48 h. Stranded animals can be a valuable source of biochemical data, but enzyme assays should be used only with great caution in post-mortem tissues.
      PubDate: 2015-05-25T18:37:22-07:00
      DOI: 10.1093/conphys/cov019
      Issue No: Vol. 3, No. 1 (2015)
  • Validation of the i-STAT and HemoCue systems for the analysis of blood
           parameters in the bar-headed goose, Anser indicus

    • Authors: Harter, T. S; Reichert, M, Brauner, C. J, Milsom, W. K.
      Abstract: Every year, bar-headed geese (Anser indicus) perform some of the most remarkable trans-Himalayan migrations, and researchers are increasingly interested in understanding the physiology underlying their high-altitude flight performance. A major challenge is generating reliable measurements of blood parameters on wild birds in the field, where established analytical techniques are often not available. Therefore, we validated two commonly used portable clinical analysers (PCAs), the i-STAT and the HemoCue systems, for the analysis of blood parameters in bar-headed geese. The pH, partial pressures of O2 and CO2 (PO2 and PCO2), haemoglobin O2 saturation (sO2), haematocrit (Hct) and haemoglobin concentration [Hb] were simultaneously measured with the two PCA systems (i-STAT for all parameters; HemoCue for [Hb]) and with conventional laboratory techniques over a physiological range of PO2, PCO2 and Hct. Our results indicate that the i-STAT system can generate reliable values on bar-headed goose whole blood pH, PO2, PCO2 and Hct, but we recommend correcting the obtained values using the linear equations determined here for higher accuracy. The i-STAT is probably not able to produce meaningful measurements of sO2 and [Hb] over a range of physiologically relevant environmental conditions. However, we can recommend the use of the HemoCue to measure [Hb] in the bar-headed goose, if results are corrected. We emphasize that the equations that we provide to correct PCA results are applicable only to bar-headed goose whole blood under the conditions that we tested. We encourage researchers to validate i-STAT or HemoCue results thoroughly for their specific study conditions and species in order to yield accurate results.
      PubDate: 2015-05-19T02:48:59-07:00
      DOI: 10.1093/conphys/cov021
      Issue No: Vol. 3, No. 1 (2015)
  • Measurement of free glucocorticoids: quantifying corticosteroid-binding
           globulin binding affinity and its variation within and among mammalian

    • Authors: Delehanty, B; Hossain, S, Jen, C. C, Crawshaw, G. J, Boonstra, R.
      Abstract: Plasma glucocorticoids (GCs) are commonly used as measures of stress in wildlife. A great deal of evidence indicates that only free GC (GC not bound by the specific binding protein, corticosteroid-binding globulin, CBG) leaves the circulation and exerts biological effects on GC-sensitive tissues. Free hormone concentrations are difficult to measure directly, so researchers estimate free GC using two measures: the binding affinity and the binding capacity in plasma. We provide an inexpensive saturation binding method for calculating the binding affinity (equilibrium dissociation constant, K d) of CBG that can be run without specialized laboratory equipment. Given that other plasma proteins, such as albumin, also bind GCs, the method compensates for this non-specific binding. Separation of bound GC from free GC was achieved with dextran-coated charcoal. The method provides repeatable estimates (12% coefficient of variation in the red squirrel, Tamiasciurus hudsonicus), and there is little evidence of inter-individual variation in K d (range 2.0–7.3 nM for 16 Richardson's ground squirrels, Urocitellus richardsonii). The K d values of 28 mammalian species we assessed were mostly clustered around a median of 4 nM, but five species had values between 13 and 61 nM. This pattern may be distinct from birds, for which published values are more tightly distributed (1.5–5.1 nM). The charcoal separation method provides a reliable and robust method for measuring the K d in a wide range of species. It uses basic laboratory equipment to provide rapid results at very low cost. Given the importance of CBG in regulating the biological activity of GCs, this method is a useful tool for physiological ecologists.
      PubDate: 2015-05-15T01:33:23-07:00
      DOI: 10.1093/conphys/cov020
      Issue No: Vol. 3, No. 1 (2015)
  • Thermal onset of cellular and endocrine stress responses correspond to
           ecological limits in brook trout, an iconic cold-water fish

    • Authors: Chadwick, J. G; Nislow, K. H, McCormick, S. D.
      Abstract: Climate change is predicted to change the distribution and abundance of species, yet underlying physiological mechanisms are complex and methods for detecting populations at risk from rising temperature are poorly developed. There is increasing interest in using physiological mediators of the stress response as indicators of individual and population-level response to environmental stressors. Here, we use laboratory experiments to show that the temperature thresholds in brook trout (Salvelinus fontinalis) for increased gill heat shock protein-70 (20.7°C) and plasma glucose (21.2°C) are similar to their proposed thermal ecological limit of 21.0°C. Field assays demonstrated increased plasma glucose, cortisol and heat shock protein-70 concentrations at field sites where mean daily temperature exceeded 21.0°C. Furthermore, population densities of brook trout were lowest at field sites where temperatures were warm enough to induce a stress response, and a co-occurring species with a higher thermal tolerance showed no evidence of physiological stress at a warm site. The congruence of stress responses and proposed thermal limits supports the use of these thresholds in models of changes in trout distribution under climate change scenarios and suggests that the induction of the stress response by elevated temperature may play a key role in driving the distribution of species.
      PubDate: 2015-04-28T22:15:32-07:00
      DOI: 10.1093/conphys/cov017
      Issue No: Vol. 3, No. 1 (2015)
  • Developing a new research tool for use in free-ranging cetaceans:
           recovering cortisol from harbour porpoise skin

    • Authors: Bechshoft, T; Wright, A. J, Weisser, J. J, Teilmann, J, Dietz, R, Hansen, M, Bjorklund, E, Styrishave, B.
      Abstract: We developed a chemical analytical procedure for sampling, extracting and determining epidermal skin cortisol concentrations (SCCs) in the harbour porpoise (Phocoena phocoena) using gas chromatography–tandem mass spectrometry. In brief, this involved a pressurized liquid extraction with a two-step solid-phase clean-up. A derivatization step was conducted prior to detection. To evaluate the new assay, cortisol was analysed in three different sample types obtained from four harbour porpoises: skin plates, dorsal fin skin plugs (with and without lidocaine) and epidermal scrapes. Skin cortisol concentrations could be measured using the new assay in the majority of the tested skin samples down to a minimal sample size of 49 mg dry weight (dw). Water content ranged from 10 to 46% in the plug samples, which had SCCs from 2.1 to 77.7 ng/g dw. Epidermal scrape samples had the highest water content (83–87%) and lower SCCs (0.6–15 ng/g dw), while the skin plates had intermediate water contents (60–66%) and SCCs of 2.6–13.0 ng/g dw. SCC was slightly higher in plugs with lidocaine than without (average values of 41 and 33 ng/g dw, respectively). Substantial within-individual variations in cortisol concentrations are also common in other matrices such as blood and hair. Some important factors behind this variation could be e.g. the animal's sex, age, body condition, reproductive stage, and the body region sampled, as well as season, moulting cycles and water temperature. Clearly, more research into SCCs is required. The findings described here represent the first critical steps towards using epidermal skin cell samples to assess chronic stress levels in cetaceans and the development of a widely applicable health-assessment tool in these species.
      PubDate: 2015-04-28T01:25:02-07:00
      DOI: 10.1093/conphys/cov016
      Issue No: Vol. 3, No. 1 (2015)
  • Altered neurotransmitter function in CO2-exposed stickleback (Gasterosteus
           aculeatus): a temperate model species for ocean acidification research

    • Authors: Lai, F; Jutfelt, F, Nilsson, G. E.
      Abstract: Studies on the consequences of ocean acidification for the marine ecosystem have revealed behavioural changes in coral reef fishes exposed to sustained near-future CO2 levels. The changes have been linked to altered function of GABAergic neurotransmitter systems, because the behavioural alterations can be reversed rapidly by treatment with the GABAA receptor antagonist gabazine. Characterization of the molecular mechanisms involved would be greatly aided if these can be examined in a well-characterized model organism with a sequenced genome. It was recently shown that CO2-induced behavioural alterations are not confined to tropical species, but also affect the three-spined stickleback, although an involvement of the GABAA receptor was not examined. Here, we show that loss of lateralization in the stickleback can be restored rapidly and completely by gabazine treatment. This points towards a worrying universality of disturbed GABAA function after high-CO2 exposure in fishes from tropical to temperate marine habitats. Importantly, the stickleback is a model species with a sequenced and annotated genome, which greatly facilitates future studies on underlying molecular mechanisms.
      PubDate: 2015-04-28T01:25:02-07:00
      DOI: 10.1093/conphys/cov018
      Issue No: Vol. 3, No. 1 (2015)
  • A physiological comparison of three techniques for reviving sockeye salmon
           exposed to a severe capture stressor during upriver migration

    • Authors: Raby, G. D; Wilson, S. M, Patterson, D. A, Hinch, S. G, Clark, T. D, Farrell, A. P, Cooke, S. J.
      Abstract: Capture of fish in commercial and recreational fisheries causes disruption to their physiological homeostasis and can result in delayed mortality for fish that are released. For fish that are severely impaired, it may be desirable to attempt revival prior to release to reduce the likelihood of post-release mortality. In this study, male sockeye salmon (Oncorhynchus nerka) undergoing their upriver migration were used to examine short-term physiological changes during the following three revival treatments after beach seine capture and air exposure: a pump-powered recovery box that provided ram ventilation at one of two water flow rates; and a cylindrical, in-river recovery bag, which ensured that fish were oriented into the river flow. Beach seine capture followed by a 3 min air exposure resulted in severe impairment of reflexes such that fish could not maintain positive orientation or properly ventilate. All three revival treatments resulted in significant reductions in reflex impairment within 15 min, with full recovery of reflex responses observed within 60–120 min. For most variables measured, including plasma lactate, cortisol and osmolality, there were no significant differences among revival treatments. There was some evidence for impaired recovery in the low-flow recovery box, in the form of higher haematocrit and plasma sodium. These data mirror published recovery profiles for a recovery box study in the marine environment where a survival benefit occurred, suggesting that the methods tested here are viable options for reviving salmon caught in freshwater. Importantly, with most of the benefit to animal vitality accrued in the first 15 min, prolonging recovery when fish become vigorous may not provide added benefit because the confinement itself is likely to serve as a stressor.
      PubDate: 2015-04-21T04:17:12-07:00
      DOI: 10.1093/conphys/cov015
      Issue No: Vol. 3, No. 1 (2015)
  • Moving house: long-term dynamics of corticosterone secretion are unaltered
           in translocated populations of a rare reptile (the tuatara, Sphenodon

    • Authors: Anderson, L. E; Cree, A, Towns, D. R, Nelson, N. J.
      Abstract: Translocations are an important conservation tool used to restore at-risk species to their historical range. Unavoidable procedures during translocations, such as habitat disturbance, capture, handling, processing, captivity, transport and release to a novel environment, have the potential to be stressful for most species. In this study, we examined acute and chronic stress (through the measurement of the glucocorticoid corticosterone) in a rare reptile (the tuatara, Sphenodon punctatus). We found that: (i) the acute corticosterone response remains elevated during the initial translocation process but is not amplified by cumulative stressors; and (ii) the long-term dynamics of corticosterone secretion are similar in translocated and source populations. Taken together, our results show that translocated tuatara are generally resistant to cumulative acute stressors and show no hormonal sign of chronic stress. Translocation efforts in tuatara afford the potential to reduce extinction risk and restore natural ecosystems.
      PubDate: 2015-04-11T00:02:24-07:00
      DOI: 10.1093/conphys/cov014
      Issue No: Vol. 3, No. 1 (2015)
  • Effect of food availability on the growth and thermal physiology of
           juvenile Dungeness crabs (Metacarcinus magister)

    • Authors: McLean, K. M; Todgham, A. E.
      Abstract: Juvenile Dungeness crabs spend ~1 year in the San Francisco Estuary, where they undergo considerable growth before returning to the coastal ocean. Previous studies suggest that competition, food scarcity and avoidance of conspecifics may cause some juvenile Dungeness crabs in the San Francisco Estuary to become food limited. Food limitation may force these crabs to forage in higher temperature intertidal environments in the estuary, exposing them to stressful conditions in order to sustain growth and, potentially, necessitating physiological trade-offs in energy allocation between growth and stress tolerance. To investigate the effects of food limitation on aerobic metabolism and physiological performance of crabs, we assessed growth, moulting frequency, metabolic rate, citrate synthase and malate dehydrogenase enzyme activity and cardiac performance, as an index of temperature sensitivity and upper temperature tolerance. Summer- and winter-caught crabs were acclimated to either a high- or a low-food ration for 5 weeks. Overall, our results demonstrated that while food limitation had a negative effect on growth of juvenile Dungeness crabs in both the summer and the winter feeding trials, crabs in the low-food group maintained both metabolic rate at ambient San Francisco Estuary temperatures (15°C; summer trial only) and upper temperature tolerance as determined by failure of cardiac function when compared with crabs in the high-food group (summer and winter trials). Therefore, the ability to maintain stress tolerance when food is limited appears to come as a physiological trade-off to growth. Food-limited crabs were unable to increase their metabolic rate to the same level as that achieved by well-fed crabs; therefore, if exposure to elevated temperatures persists and requires more energy than can be met by crabs in their food-limited state, physiological performance may be compromised.
      PubDate: 2015-03-31T23:00:24-07:00
      DOI: 10.1093/conphys/cov013
      Issue No: Vol. 3, No. 1 (2015)
  • Selective logging: does the imprint remain on tree structure and
           composition after 45 years?

    • Authors: Osazuwa-Peters, O. L; Chapman, C. A, Zanne, A. E.
      Abstract: Selective logging of tropical forests is increasing in extent and intensity. The duration over which impacts of selective logging persist, however, remains an unresolved question, particularly for African forests. Here, we investigate the extent to which a past selective logging event continues to leave its imprint on different components of an East African forest 45 years later. We inventoried 2358 stems ≥10 cm in diameter in 26 plots (200 m x 10 m) within a 5.2 ha area in Kibale National Park, Uganda, in logged and unlogged forest. In these surveys, we characterized the forest light environment, taxonomic composition, functional trait composition using three traits (wood density, maximum height and maximum diameter) and forest structure based on three measures (stem density, total basal area and total above-ground biomass). In comparison to unlogged forests, selectively logged forest plots in Kibale National Park on average had higher light levels, different structure characterized by lower stem density, lower total basal area and lower above-ground biomass, and a distinct taxonomic composition driven primarily by changes in the relative abundance of species. Conversely, selectively logged forest plots were like unlogged plots in functional composition, having similar community-weighted mean values for wood density, maximum height and maximum diameter. This similarity in functional composition irrespective of logging history may be due to functional recovery of logged forest or background changes in functional attributes of unlogged forest. Despite the passage of 45 years, the legacy of selective logging on the tree community in Kibale National Park is still evident, as indicated by distinct taxonomic and structural composition and reduced carbon storage in logged forest compared with unlogged forest. The effects of selective logging are exerted via influences on tree demography rather than functional trait composition.
      PubDate: 2015-03-24T22:29:36-07:00
      DOI: 10.1093/conphys/cov012
      Issue No: Vol. 3, No. 1 (2015)
  • Seahorses under a changing ocean: the impact of warming and acidification
           on the behaviour and physiology of a poor-swimming bony-armoured fish

    • Authors: Faleiro, F; Baptista, M, Santos, C, Aurelio, M. L, Pimentel, M, Pegado, M. R, Paula, J. R, Calado, R, Repolho, T, Rosa, R.
      Abstract: Seahorses are currently facing great challenges in the wild, including habitat degradation and overexploitation, and how they will endure additional stress from rapid climate change has yet to be determined. Unlike most fishes, the poor swimming skills of seahorses, along with the ecological and biological constraints of their unique lifestyle, place great weight on their physiological ability to cope with climate changes. In the present study, we evaluate the effects of ocean warming (+4°C) and acidification (pH = –0.5 units) on the physiological and behavioural ecology of adult temperate seahorses, Hippocampus guttulatus. Adult seahorses were found to be relatively well prepared to face future changes in ocean temperature, but not the combined effect of warming and acidification. Seahorse metabolism increased normally with warming, and behavioural and feeding responses were not significantly affected. However, during hypercapnia the seahorses exhibited signs of lethargy (i.e. reduced activity levels) combined with a reduction of feeding and ventilation rates. Nonetheless, metabolic rates were not significantly affected. Future ocean changes, particularly ocean acidification, may further threaten seahorse conservation, turning these charismatic fishes into important flagship species for global climate change issues.
      PubDate: 2015-03-18T18:07:03-07:00
      DOI: 10.1093/conphys/cov009
      Issue No: Vol. 3, No. 1 (2015)
  • Feeling the heat: the effect of acute temperature changes on predator-prey
           interactions in coral reef fish

    • Authors: Allan, B. J. M; Domenici, P, Munday, P. L, McCormick, M. I.
      Abstract: Recent studies demonstrate that the elevated temperatures predicted to occur by the end of the century can affect the physiological performance and behaviour of larval and juvenile fishes; however, little is known of the effect of these temperatures on ecological processes, such as predator–prey interactions. Here, we show that exposure to elevated temperatures significantly affected the predator–prey interactions of a pair of common reef fish, the planktivorous damselfish (Pomacentrus wardi) and the piscivorous dottyback (Pseudochromis fuscus). When predators exposed to elevated temperatures interacted with prey exposed in a similar manner, maximal attack speeds increased. This effect coupled with decreasing prey escape speeds and escape distances led to increased predation rates. Prey exposed to elevated temperatures also had decreased reaction distances and increased apparent looming threshold, suggesting that their sensory performance was affected. This occurred despite the increase in maximal attack speeds, which in other species has been shown to increase reaction distances. These results suggest that the escape performance of prey is sensitive to short-term increases in ambient temperature. As marine environments become more thermally variable in the future, our results demonstrate that some predators may become more successful, suggesting that there will be strong selection for the maintenance of maximal escape performance in prey. In the present era of rapid climate change, understanding how changes to individual performance influence the relationships between predators and their prey will be increasingly important in predicting the effects of climate change within ecosystems.
      PubDate: 2015-03-16T00:35:22-07:00
      DOI: 10.1093/conphys/cov011
      Issue No: Vol. 3, No. 1 (2015)
  • Carotenoids and amphibians: effects on life history and susceptibility to
           the infectious pathogen, Batrachochytrium dendrobatidis

    • Authors: Cothran, R. D; Gervasi, S. S, Murray, C, French, B. J, Bradley, P. W, Urbina, J, Blaustein, A. R, Relyea, R. A.
      Abstract: Carotenoids are considered beneficial nutrients because they provide increased immune capacity. Although carotenoid research has been conducted in many vertebrates, little research has been done in amphibians, a group that is experiencing global population declines from numerous causes, including disease. We raised two amphibian species through metamorphosis on three carotenoid diets to quantify the effects on life-history traits and post-metamorphic susceptibility to a fungal pathogen (Batrachochytrium dendrobatidis; Bd). Increased carotenoids had no effect on survival to metamorphosis in gray treefrogs (Hyla versicolor) but caused lower survival to metamorphosis in wood frogs [Lithobates sylvaticus (Rana sylvatica)]. Increased carotenoids caused both species to experience slower development and growth. When exposed to Bd after metamorphosis, wood frogs experienced high mortality, and the carotenoid diets had no mitigating effects. Gray treefrogs were less susceptible to Bd, which prevented an assessment of whether carotenoids could mitigate the effects of Bd. Moreover, carotenoids had no effect on pathogen load. As one of only a few studies examining the effects of carotenoids on amphibians and the first to examine potential interactions with Bd, our results suggest that carotenoids do not always serve amphibians in the many positive ways that have become the paradigm in other vertebrates.
      PubDate: 2015-03-13T23:40:12-07:00
      DOI: 10.1093/conphys/cov005
      Issue No: Vol. 3, No. 1 (2015)
  • Redtail and red colobus monkeys show intersite urinary cortisol
           concentration variation in Kibale National Park, Uganda

    • Authors: Aronsen, G. P; Beuerlein, M. M, Watts, D. P, Bribiescas, R. G.
      Abstract: Non-invasive measurement of urinary cortisol is a proven method of evaluating the impact of environmental stressors on wild primates. Variation in cortisol concentrations can reflect physiological stress, and prolonged elevation of circulating cortisol can significantly affect individual and population-level health. In a previous study, we found that urinary cortisol concentrations in grey-cheeked mangabeys (Lophocebus albigena) were higher at a highly disturbed site (Mainaro) in Kibale National Park, Uganda compared with a minimally disturbed site (Ngogo) in the same habitat. Here, we expand on this research, reporting on cortisol concentrations in two other cercopithecid monkeys (Cercopithecus ascanius and Piliocolobus rufomitratus) at the same two sites. We hypothesized that C. ascanius would show no difference between sites, given its preference for secondary forests, while P. rufomitratus would have higher cortisol concentrations at the disturbed site. Contrary to expectations, both species exhibited significantly higher cortisol concentrations at Ngogo (minimally disturbed) compared with Mainaro (disturbed). We suggest that these results may be caused by inter- or intragroup social dynamics, intersite differences in predation rate, fruit/food availability and chemistry, or a combination of these factors. These initial evaluations of urinary cortisol concentrations provide testable hypotheses on habitat disturbance and Kibale primate ecophysiology.
      PubDate: 2015-03-13T23:40:12-07:00
      DOI: 10.1093/conphys/cov006
      Issue No: Vol. 3, No. 1 (2015)
  • The influence of time in captivity, food intake and acute trauma on blood
           analytes of juvenile Steller sea lions, Eumetopias jubatus

    • Authors: Skinner, J. P; Tuomi, P. A, Mellish, J.-A. E.
      Abstract: The Steller sea lion, Eumetopias jubatus, has experienced regionally divergent population trends over recent decades. One potential mechanism for this disparity is that local factors cause reduced health and, therefore, reduced survival of individuals. The use of blood parameters to assess sea lion health may help to identify whether malnutrition, disease and stress are important drivers of current trends, but such assessments require species-specific knowledge of how parameters respond to various health challenges. We used principal components analysis to identify which key blood parameters (principal analytes) best described changes in health for temporarily captive juvenile Steller sea lions in known conditions. Generalized additive mixed models were used to estimate the changes in principal analytes with food intake, time in captivity and acute trauma associated with hot-iron branding and transmitter implant surgery. Of the 17 blood parameters examined, physiological changes for juvenile sea lions were best described using the following six principal analytes: red blood cell counts, white blood cell counts, globulin, platelets, glucose and total bilirubin. The white blood cell counts and total bilirubin declined over time in captivity, whereas globulin increased. Elevated red blood cell counts, white blood cell counts and total bilirubin and reduced globulin values were associated with lower food intake. After branding, white blood cell counts were elevated for the first 30 days, while globulin and platelets were elevated for the first 15 days only. After implant surgery, red blood cell counts and globulin remained elevated for 30 days, while white blood cell counts remained elevated during the first 15 days only. Glucose was unassociated with the factors we studied. These results were used to provide expected ranges for principal analytes at different levels of food intake and in response to the physical challenges of branding and implant surgery. These results provide a more detailed reference for future evaluations of health-related assessments.
      PubDate: 2015-03-13T23:40:12-07:00
      DOI: 10.1093/conphys/cov008
      Issue No: Vol. 3, No. 1 (2015)
  • Does greater thermal plasticity facilitate range expansion of an invasive
           terrestrial anuran into higher latitudes?

    • Authors: Winwood-Smith, H. S; Alton, L. A, Franklin, C. E, White, C. R.
      Abstract: Temperature has pervasive effects on physiological processes and is critical in setting species distribution limits. Since invading Australia, cane toads have spread rapidly across low latitudes, but slowly into higher latitudes. Low temperature is the likely factor limiting high-latitude advancement. Several previous attempts have been made to predict future cane toad distributions in Australia, but understanding the potential contribution of phenotypic plasticity and adaptation to future range expansion remains challenging. Previous research demonstrates the considerable thermal metabolic plasticity of the cane toad, but suggests limited thermal plasticity of locomotor performance. Additionally, the oxygen-limited thermal tolerance hypothesis predicts that reduced aerobic scope sets thermal limits for ectotherm performance. Metabolic plasticity, locomotor performance and aerobic scope are therefore predicted targets of natural selection as cane toads invade colder regions. We measured these traits at temperatures of 10, 15, 22.5 and 30°C in low- and high-latitude toads acclimated to 15 and 30°C, to test the hypothesis that cane toads have adapted to cooler temperatures. High-latitude toads show increased metabolic plasticity and higher resting metabolic rates at lower temperatures. Burst locomotor performance was worse for high-latitude toads. Other traits showed no regional differences. We conclude that increased metabolic plasticity may facilitate invasion into higher latitudes by maintaining critical physiological functions at lower temperatures.
      PubDate: 2015-03-13T23:40:12-07:00
      DOI: 10.1093/conphys/cov010
      Issue No: Vol. 3, No. 1 (2015)
  • Adrenal sensitivity to stress is maintained despite variation in baseline
           glucocorticoids in moulting seals

    • Authors: Champagne, C; Tift, M, Houser, D, Crocker, D.
      Abstract: Stressful disturbances activate the hypothalamic–pituitary–adrenal (HPA) axis and result in the release of glucocorticoid (GC) hormones. This characteristic stress response supports immediate energetic demands and subsequent recovery from disturbance. Increased baseline GC concentrations may indicate chronic stress and can impair HPA axis function during exposure to additional stressors. Levels of GCs, however, vary seasonally and with life-history stage, potentially confounding their interpretation. Our objective was to evaluate HPA axis function across variations in baseline GC levels. Northern elephant seals show substantial baseline variation in GC levels during their annual moulting period. We therefore conducted measurements early, in the middle and at the end of moulting; we simulated an acute stressor by administering adrenocorticotrophic hormone and evaluated the changes in circulating hormones and metabolites over the following 2 h. The stress response was characterized by increases in both cortisol and aldosterone (F 7,105 = 153 and 25.3, respectively; P 
      PubDate: 2015-03-11T20:54:40-07:00
      DOI: 10.1093/conphys/cov004
      Issue No: Vol. 3, No. 1 (2015)
  • The use of haemoglobin concentrations to assess physiological condition in
           birds: a review

    • Authors: Minias; P.
      Abstract: Total blood haemoglobin concentration is increasingly being used to assess physiological condition in wild birds, although it has not been explicitly recognized how reliably this parameter reflects different components of individual quality. Thus, I reviewed over 120 published studies linking variation in haemoglobin concentrations to different measures of condition and other phenotypic or ecological traits. In most of the studied avian species, haemoglobin concentrations were positively correlated with other commonly used indices of condition, such as body mass and fat loads, as well as with quality of the diet. Also, chick haemoglobin concentrations reliably reflected the intensity of nest infestation by parasitic arthropods, and haemoglobin was suggested to reflect parasitism by haematophagous ectoparasites much more precisely than haematocrit. There was also some evidence for the negative effect of helminths on haemoglobin levels in adult birds. Finally, haemoglobin concentrations were found to correlate with such fitness-related traits as timing of arrival at breeding grounds, timing of breeding, egg size, developmental stability and habitat quality, although these relationships were not always consistent between species. In consequence, I recommend the total blood haemoglobin concentration as a relatively robust indicator of physiological condition in birds, although this parameter is also strongly affected by age, season and the process of moult. Thus, researchers are advised to control fully for these confounding effects while using haemoglobin concentrations as a proxy of physiological condition in both experimental and field studies on birds.
      PubDate: 2015-03-11T20:54:40-07:00
      DOI: 10.1093/conphys/cov007
      Issue No: Vol. 3, No. 1 (2015)
  • Optimal migration energetics of humpback whales and the implications of

    • Authors: Braithwaite, J. E; Meeuwig, J. J, Hipsey, M. R.
      Abstract: Whales migrate long distances and reproduce on a finite store of energy. Budgeting the use of this limited energy reserve is an important factor to ensure survival over the period of migration and to maximize reproductive investment. For some whales, migration routes are closely associated with coastal areas, exposing animals to high levels of human activity. It is currently unclear how various forms of human activity may disturb whales during migration, how this might impact their energy balance and how this could translate into long-term demographic changes. Here, we develop a theoretical bioenergetic model for migrating humpback whales to investigate the optimal migration strategy that minimizes energy use. The average migration velocity was an important driver of the total energy used by a whale, and an optimal velocity of 1.1 m s–1 was determined. This optimal velocity is comparable to documented observed migration speeds, suggesting that whales migrate at a speed that conserves energy. Furthermore, the amount of resting time during migration was influenced by both transport costs and feeding rates. We simulated hypothetical disturbances to the optimal migration strategy in two ways, by altering average velocity to represent changes in behavioural activity and by increasing total travelled distance to represent displacement along the migration route. In both cases, disturbance increased overall energy use, with implications for the growth potential of calves.
      PubDate: 2015-03-09T01:21:04-07:00
      DOI: 10.1093/conphys/cov001
      Issue No: Vol. 3, No. 1 (2015)
  • Validation of the i-STAT system for the analysis of blood gases and
           acid-base status in juvenile sandbar shark (Carcharhinus plumbeus)

    • Authors: Harter, T. S; Morrison, P. R, Mandelman, J. W, Rummer, J. L, Farrell, A. P, Brill, R. W, Brauner, C. J.
      Abstract: Accurate measurements of blood gases and acid–base status require an array of sophisticated laboratory equipment that is typically not available during field research; such is the case for many studies on the stress physiology, ecology and conservation of elasmobranch fish species. Consequently, researchers have adopted portable clinical analysers that were developed for the analysis of human blood characteristics, but often without thoroughly validating these systems for their use on fish. The aim of our study was to test the suitability of the i-STAT system, the most commonly used portable clinical analyser in studies on fish, for analysing blood gases and acid–base status in elasmobranchs, over a broad range of conditions and using the sandbar shark (Carcharhinus plumbeus) as a model organism. Our results indicate that the i-STAT system can generate useful measurements of whole blood pH, and the use of appropriate correction factors may increase the accuracy of results. The i-STAT system was, however, unable to generate reliable results for measurements of partial pressure of oxygen (PO2) and the derived parameter of haemoglobin O2 saturation. This is probably due to the effect of a closed-system temperature change on PO2 within the i-STAT cartridge and the fact that the temperature correction algorithms used by i-STAT assume a human temperature dependency of haemoglobin–O2 binding; in many ectotherms, this assumption will lead to equivocal i-STAT PO2 results. The in vivo partial pressure of CO2 (PCO2) in resting sandbar sharks is probably below the detection limit for PCO2 in the i-STAT system, and the measurement of higher PCO2 tensions was associated with a large measurement error. In agreement with previous work, our results indicate that the i-STAT system can generate useful data on whole blood pH in fishes, but not blood gases.
      PubDate: 2015-03-01T23:35:05-08:00
      DOI: 10.1093/conphys/cov002
      Issue No: Vol. 3, No. 1 (2015)
  • Baseline plasma corticosterone, haematological and biochemical results in
           nesting and rehabilitating loggerhead sea turtles (Caretta caretta)

    • Authors: Flower, J. E; Norton, T. M, Andrews, K. M, Nelson, S. E, Parker, C. E, Romero, L. M, Mitchell, M. A.
      Abstract: The evaluation of hormonal responses to stress in reptiles relies on acquisition of baseline corticosterone concentrations; however, the stress associated with the restraint needed to collect the blood samples can affect the results. The purpose of this study was to determine a time limit for the collection of blood samples to evaluate baseline corticosterone, haematological and biochemical results in nesting (n = 11) and rehabilitating (n = 16) loggerhead sea turtles (Caretta caretta). Blood samples were collected from the dorsal cervical sinus of each turtle immediately after touching the animal (t 0; 0–3 min) and 3 (t 3; 3–6 min), 6 (t 6; 6–9 min; nesting turtles only), 10 (t 10; 10–13 min) and 30 min (t 30; rehabilitating turtles only) after the initial hands-on time. Consistent between the rehabilitating and nesting turtles, there was a subtle yet significant increase in white blood cell counts over time. Despite the fact that white blood cell counts increased during the sampling period, there was no direct correlation between white blood cell count and corticosterone in the sampled turtles. In the nesting turtles, significant elevations in corticosterone were noted between t 0 and t 3 (P = 0.014) and between t 0 and t 6 (P = 0.022). Values at t 10 were not significantly different from those at t 0 (P = 0.102); however, there was a trend for the corticosterone values to continue to increase. These results suggest that sampling of nesting loggerhead sea turtles within 3 min of handling will provide baseline corticosterone concentrations in their natural environment. Significant elevations in corticosterone were also noted in the rehabilitating loggerhead sea turtles between t 0 and t 10 (P = 0.02) and between t 0 and t 30 of sampling (P = 0.0001). These results suggest that sampling of loggerhead sea turtles within 6 min of handling should provide baseline corticosterone concentrations in a rehabilitation setting. The delay in the corticosterone response noted in the rehabilitating turtles may be associated with the daily contact (visual or direct) they have with their human caretakers.
      PubDate: 2015-03-01T21:37:07-08:00
      DOI: 10.1093/conphys/cov003
      Issue No: Vol. 3, No. 1 (2015)
  • Physiological effects of heat stress on Hawaiian picture-wing Drosophila:
           genome-wide expression patterns and stress-related traits

    • Authors: Uy, K. L; LeDuc, R, Ganote, C, Price, D. K.
      Abstract: Climate change is compounding the threats to the future of biodiversity, already impacted by habitat loss, invasive species and diseases. In the Hawaiian Islands, many of the endemic species have narrow habitat ranges that make them especially vulnerable to climate change. The Hawaiian Drosophila, a remarkably diverse group of species with 11 listed as federally endangered, are thought to be sensitive to temperature changes. To examine the species differences in sensitivity of Hawaiian picture-wing Drosophila to temperature changes, wild populations of Drosophila sproati, a relatively common species, and Drosophila silvestris, a rare species, were collected from two locations on Hawaii Island and bred in common laboratory conditions. Adult flies were exposed to hot and cold temperatures and compared with adult flies at control temperatures. Drosophila silvestris adults were less tolerant to heat stress than D. sproati for both survival and sperm mobility. In contrast, D. silvestris adults were more tolerant to cold stress than D. sproati for adult survival. The expression of 4950 Gene Ontology annotated gene transcripts was also analysed in high-temperature-treated and control males to identify candidate genes related to heat tolerance. There were more than twice as many transcripts differentially expressed after high temperature treatment for D. silvestris (246 transcripts) as for D. sproati (106 transcripts), with 13 Gene Ontology terms enriched between temperatures for D. silvestris and merely three in D. sproati. The combined results are consistent with D. sproati occurring more widely today as well as occurring at lower elevations than D. silvestris and with a genetically based temperature response, which is more severe in D. silvestris at high temperatures than that in D. sproati. These experiments demonstrate the potential for different capacities of species to adapt to future climate change conditions as well as providing an explanation for historical changes in the distribution of species.
      PubDate: 2015-02-18T21:12:54-08:00
      DOI: 10.1093/conphys/cou062
      Issue No: Vol. 3, No. 1 (2015)
  • Predator-induced renesting and reproductive effort in indigo buntings:
           more work for less pay'

    • Authors: Morris, D. L; Faaborg, J, Washburn, B. E, Millspaugh, J. J.
      Abstract: Renesting after nest predation is ultimately an adaptive response to increase productivity in birds. However, renesting also increases reproductive effort to replace lost clutches. We investigated the consequences of this increased reproductive effort by determining whether renesting in female indigo buntings (Passerina cyanea) is associated with a decline in body condition (size-corrected mass) and haematocrit and an increase in stress hormones and whether renesting or maternal body condition is associated with a decline in productivity (clutch size, nestling body condition). Next, because a consequence of multiple renesting attempts is a prolonged breeding season and later timing, we predicted that a population of post-breeding females and juveniles would have lower body condition in fragmented forest than in contiguous forest owing to higher nest predation and frequency of renesting. Both forest types were settled by females of similar condition. Nest survival was lower in fragmented forest, where a higher proportion of females failed their first attempt and the breeding season was 2 weeks longer. Compared with females on their first attempt, renesting females had lower body condition and haematocrit and higher corticosterone concentrations. Lower maternal body condition was associated with higher concentrations of corticosterone, lower nestling body condition and smaller clutches. Clutch size was lower in renests and in fragmented forest. Nestling condition was lower in renests but did not vary greatly with forest type. Despite a prolonged breeding season in the fragmented forest, post-breeding females and hatch-year birds were in similar condition in both forest types. Our results suggest that the indirect effects of nest predation on maternal and offspring condition pose additional individual-level costs that have not been considered in the context of fragmentation studies. We discuss how predator-induced renesting could have additional demographic consequences by prolonging the breeding season and prompting seasonal interactions or carry-over effects that could impact populations.
      PubDate: 2015-02-04T23:22:59-08:00
      DOI: 10.1093/conphys/cou063
      Issue No: Vol. 3, No. 1 (2015)
  • Migration depth and residence time of juvenile salmonids in the forebays
           of hydropower dams prior to passage through turbines or juvenile bypass
           systems: implications for turbine-passage survival

    • Authors: Li, X; Deng, Z. D, Brown, R. S, Fu, T, Martinez, J. J, McMichael, G. A, Skalski, J. R, Townsend, R. L, Trumbo, B. A, Ahmann, M. L, Renholds, J. F.
      Abstract: Little is known about the three-dimensional depth distributions in rivers of individually marked fish that are in close proximity to hydropower facilities. Knowledge of the depth distributions of fish approaching dams can be used to understand how vulnerable fish are to injuries such as barotrauma as they pass through dams. To predict the possibility of barotrauma injury caused by pressure changes during turbine passage, it is necessary to understand fish behaviour relative to acclimation depth in dam forebays as they approach turbines. A guiding study was conducted using high-resolution three-dimensional tracking results of salmonids implanted with Juvenile Salmon Acoustic Telemetry System transmitters to investigate the depth distributions of subyearling and yearling Chinook salmon (Oncorhynchus tshawytscha) and juvenile steelhead (Oncorhynchus mykiss) passing two dams on the Snake River in Washington State. Multiple approaches were evaluated to describe the depth at which fish were acclimated, and statistical analyses were performed on large data sets extracted from ~28 000 individually tagged fish during 2012 and 2013. Our study identified patterns of depth distributions of juvenile salmonids in forebays prior to passage through turbines or juvenile bypass systems. This research indicates that the median depth at which juvenile salmonids approached turbines ranged from 2.8 to 12.2 m, with the depths varying by species/life history, year, location (which dam) and diel period (between day and night). One of the most enlightening findings was the difference in dam passage associated with the diel period. The amount of time that turbine-passed fish spent in the immediate forebay prior to entering the powerhouse was much lower during the night than during the day. This research will allow scientists to understand turbine-passage survival better and enable them to assess more accurately the effects of dam passage on juvenile salmon survival.
      PubDate: 2015-02-03T17:14:17-08:00
      DOI: 10.1093/conphys/cou064
      Issue No: Vol. 3, No. 1 (2015)
  • Predicting future thermal habitat suitability of competing native and
           invasive fish species: from metabolic scope to oceanographic modelling

    • Authors: Marras, S; Cucco, A, Antognarelli, F, Azzurro, E, Milazzo, M, Bariche, M, Butenschon, M, Kay, S, Di Bitetto, M, Quattrocchi, G, Sinerchia, M, Domenici, P.
      Abstract: Global increase in sea temperatures has been suggested to facilitate the incoming and spread of tropical invaders. The increasing success of these species may be related to their higher physiological performance compared with indigenous ones. Here, we determined the effect of temperature on the aerobic metabolic scope (MS) of two herbivorous fish species that occupy a similar ecological niche in the Mediterranean Sea: the native salema (Sarpa salpa) and the invasive marbled spinefoot (Siganus rivulatus). Our results demonstrate a large difference in the optimal temperature for aerobic scope between the salema (21.8°C) and the marbled spinefoot (29.1°C), highlighting the importance of temperature in determining the energy availability and, potentially, the distribution patterns of the two species. A modelling approach based on a present-day projection and a future scenario for oceanographic conditions was used to make predictions about the thermal habitat suitability (THS, an index based on the relationship between MS and temperature) of the two species, both at the basin level (the whole Mediterranean Sea) and at the regional level (the Sicilian Channel, a key area for the inflow of invasive species from the Eastern to the Western Mediterranean Sea). For the present-day projection, our basin-scale model shows higher THS of the marbled spinefoot than the salema in the Eastern compared with the Western Mediterranean Sea. However, by 2050, the THS of the marbled spinefoot is predicted to increase throughout the whole Mediterranean Sea, causing its westward expansion. Nevertheless, the regional-scale model suggests that the future thermal conditions of Western Sicily will remain relatively unsuitable for the invasive species and could act as a barrier for its spread westward. We suggest that metabolic scope can be used as a tool to evaluate the potential invasiveness of alien species and the resilience to global warming of native species.
      PubDate: 2015-01-21T00:54:52-08:00
      DOI: 10.1093/conphys/cou059
      Issue No: Vol. 3, No. 1 (2015)
  • Detection of oocyte perivitelline membrane-bound sperm: a tool for avian
           collection management

    • Authors: Croyle, K. E; Durrant, B. S, Jensen, T.
      Abstract: The success and sustainability of an avian breeding programme depend on managing productive and unproductive pairs. Given that each breeding season can be of immeasurable importance, it is critical to resolve pair fertility issues quickly. Such problems are traditionally diagnosed through behavioural observations, egg lay history and hatch rates, with a decision to re-pair generally taking one or more breeding seasons. In pairs producing incubated eggs that show little or no signs of embryonic development, determining fertility is difficult. Incorporating a technique to assess sperm presence on the oocyte could, in conjunction with behaviour and other data, facilitate a more timely re-pair decision. Detection of perivitelline membrane-bound (PVM-bound) sperm verifies successful copulation, sperm production and sperm functionality. Alternatively, a lack of detectable sperm, at least in freshly laid eggs, suggests no mating, lack of sperm production/function or sperm–oviduct incompatibility. This study demonstrated PVM-bound sperm detection by Hoechst staining in fresh to 24-day-incubated exotic eggs from 39 species representing 13 orders. However, a rapid and significant time-dependent loss of detectable PVM-bound sperm was observed following incubation of chicken eggs. The PCR detection of sperm in seven species, including two bacterially infected eggs, demonstrated that this method was not as reliable as visual detection using Hoechst staining. The absence of amplicons in visually positive PVMs was presumably due to large PVM size and low sperm count, resulting in DNA concentrations too low for standard PCR detection. In summary, this study demonstrated the feasibility and limitations of using PVM-bound sperm detection as a management tool for exotic avian species. We verified that sperm presence or absence on fluorescence microscopy can aid in the differentiation of fertile from infertile eggs to assist breeding managers in making prompt decisions for pair rearrangements. This protocol is currently used to manage several breeding pairs in San Diego Zoo global avian conservation programmes.
      PubDate: 2015-01-18T23:16:52-08:00
      DOI: 10.1093/conphys/cou060
      Issue No: Vol. 3, No. 1 (2015)
  • Effects of anthropogenic noise on endocrine and reproductive function in
           White's treefrog, Litoria caerulea

    • Authors: Kaiser, K; Devito, J, Jones, C. G, Marentes, A, Perez, R, Umeh, L, Weickum, R. M, McGovern, K. E, Wilson, E. H, Saltzman, W.
      Abstract: Urbanization is a major driver of ecological change and comes with a suite of habitat modifications, including alterations to the local temperature, precipitation, light and noise regimes. Although many recent studies have investigated the behavioural and ecological ramifications of urbanization, physiological work in this area has lagged. We tested the hypothesis that anthropogenic noise is a stressor for amphibians and that chronic exposure to such noise leads to reproductive suppression. In the laboratory, we exposed male White's treefrogs, Litoria caerulea, to conspecific chorus noise either alone or coupled with pre-recorded traffic noise nightly for 1 week. Frogs presented with anthropogenic noise had significantly higher circulating concentrations of corticosterone and significantly decreased sperm count and sperm viability than did control frogs. These results suggest that in addition to having behavioural and ecological effects, anthropogenic change might alter physiology and Darwinian fitness. Future work should integrate disparate fields such as behaviour, ecology and physiology to elucidate fully organisms’ responses to habitat change.
      PubDate: 2015-01-16T02:43:53-08:00
      DOI: 10.1093/conphys/cou061
      Issue No: Vol. 3, No. 1 (2015)
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