Conservation Physiology最新文献

Catch-and-release angling exposes fish to challenges that may result in sub-lethal effects or mortality. Lake trout (Salvelinus namaycush) undergo high rates of release because of size-based harvest regulations or voluntary angler behaviour. Here, we examine short-term impairment in lake trout angled during the summer (n = 74) and fall spawning period (n = 33) to inform best practices for angling. Immediately following capture or 0.5 h post-capture, fish underwent reflex and barotrauma assessments, and a small blood sample was collected. Fish were also fitted with an externally mounted biologger equipped with depth, temperature and tri-axial acceleration sensors, that was tethered to allow retrieval of the logger after 14 min. In the summer, reflex impairment and barotrauma at 0 and 0.5 h were significantly correlated. Loss of orientation and bloating were the most observed indicators. Larger fish and those captured at increased depth had higher barotrauma scores, while prolonged fight times decreased the barotrauma score regardless of sampling time. Plasma cortisol, lactate and glucose increased 0.5 h after capture, and extracellular and intracellular pH decreased, all signs that angling was inducing a metabolic response. However, no relationships were found between blood indices and mortality (18.9%). The time required to reach maximum depth after release was longer for fish with increased air exposure but shorter for those with longer fight times. During the fall, fish displayed no mortality or reflex impairment. Anal prolapse was the most observed indicator of barotrauma but only observed in females. Blood indices were most altered 0.5 h after capture, with increased cortisol values for fish that were female, particularly large or captured at deeper depth. Locomotor activity was highest for males and increased with depth. Together, our findings suggest that the effects of catch-and-release angling may be dependent on several factors, including sex, season and angling depth.

Concerted conservation efforts have brought the giant panda (Ailuropoda melanoleuca) back from the brink of extinction, but pandas continue to face anthropogenic threats in the wild and breeding success in captivity remains low. Because stress can have detrimental impacts on reproduction, monitoring stress- and sex-steroid levels would help assess the effectiveness of conservation mitigation measures in panda populations as well as monitor the welfare and reproductive health of captive animals. In this proof-of-concept study, we used faecal sex steroid and cortisol concentrations (n = 867 samples collected from five males and five females at Beijing Zoo every 4 days over the course of 12 months) as a reference to investigate if testosterone, estradiol, progesterone and cortisol can be meaningfully measured in panda hair (n = 10) using radio-immuno-assays. Additionally, we calculated the ratio of testosterone to cortisol (T:C ratio) for each male, which can provide a biomarker of stress and physical performance. Our findings revealed distinct monthly variations in faecal sex-steroid and cortisol concentrations, reflecting reproductive seasonality and visitor-related stress among individual pandas. Notably, the oldest male had a significantly lower T:C ratio than other males. Our results confirm that the level of sex steroids and cortisol can be assayed by panda hair, and the hair cortisol concentrations correlate significantly with that in faeces with one month lag behind (r = 0.68, P = 0.03). However, the concentrations of hormones detected in saliva are lower than those in faeces by two orders of magnitude, making it difficult to ensure accuracy. By assessing the applicability of hair, faecal and salivary sampling, we can infer their utility in monitoring the reproductive status and acute and chronic stress levels of giant pandas, thereby providing a means to gauge the success of ongoing habitat restoration efforts and to discuss the feasibility of sample collection from wild populations.

Forest fragmentation and edge effects are two major threats to primate populations. Primates inhabiting fragmented landscapes must survive in a more degraded environment, often with lower food availability compared to continuous forests. Such conditions can have deleterious effects on animal physiological health, yet some primates thrive in these habitats. Here, we assessed how forest fragmentation and associated edge effects impact three different components of physiological health in a nocturnal primate community in the Sahamalaza-Iles Radama National Park, northwest Madagascar. Over two periods, 6 March 2019-30 October 2019 and 10 January 2022-17 May 2022, we collected data on body condition, fur condition scores and ectoparasite prevalence for 125 Mirza zaza, 51 Lepilemur sahamalaza, 27 Cheirogaleus medius and 22 Microcebus sambiranensis individuals, and we compared these metrics between core and edge areas of continuous forest and fragmented forest. Body condition scores for all species varied between areas, with a positive response to fragmentation and edge effects observed for M. zaza and L. sahamalaza and a negative response for C. medius and M. sambiranensis. Fur condition scores and ectoparasite prevalence were less variable, although M. zaza and L. sahamalaza had a significantly negative response to fragmentation and edge effects for these two variables. Interestingly, the impacts of fragmentation and edge effects on physiological health were variable-specific. Our results suggest that lemur physiological responses to fragmentation and edge effects are species-specific, and body condition, fur condition and ectoparasite prevalence are impacted in different ways between species. As other ecological factors, including food availability and inter/intraspecific competition, likely also influence physiological health, additional work is required to determine why certain aspects of lemur physiology are affected by environmental stressors while others remain unaffected. Although many nocturnal lemurs demonstrate resilience to fragmented and degraded habitats, urgent conservation action is needed to safeguard the survival of their forest habitats.

The Chinese pangolin (Manis pentadactyla) is a critically endangered species. However, there is a paucity of research on the male reproductive gamete biology of this species. The present study was the first to systematically analyse the sperm characterization of the Chinese pangolin, including semen collection, sperm morphometry and ultrastructure. The semen of five male Chinese pangolins was successfully collected using the electroejaculation method. CASA (computer-assisted sperm analysis) was used to assess semen quality and take images for sperm morphometric analysis. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for sperm ultrastructure observation. The results showed that the semen of the Chinese pangolin was yellow to pale yellow in colour, viscous, with a fishy odour, and a slightly alkaline pH of between 7.7 and 7.9. The head defects were the main sperm defects; there were 13 kinds of head defects counted in this study. The total sperm length, head length, head width and tail length were 67.62 ± 0.21 μm, 10.47 ± 0.06 μm, 1.33 ± 0.006 μm and 57.16 ± 0.20 μm, respectively. SEM observed that the spermatozoa had a rod-shaped head with a distinct apical ridge, which was different from most mammals and similar to that in avians and reptiles. Interestingly, TEM found that the acrosome membrane of the Chinese pangolin had a double membrane structure rather than a multiple bi-lamellar membrane structure as reported by the previous study. Collectively, this study contributes to the development of artificial breeding efforts and assisted reproductive techniques for the Chinese pangolin, as well as providing technical support for research on germplasm conservation of this species.

The passive dissolution of anthropogenically produced CO₂ into the ocean system is reducing ocean pH and changing a suite of chemical equilibria, with negative consequences for some marine organisms, in particular those that bear calcium carbonate shells. Although our monitoring of these chemical changes has improved, we have not developed effective tools to translate observations, which are typically of the pH and carbonate saturation state, into ecologically relevant predictions of biological risks. One potential solution is to develop bioindicators: biological variables with a clear relationship to environmental risk factors that can be used for assessment and management. Thecosomatous pteropods are a group of pelagic shelled marine gastropods, whose biological responses to CO₂ have been suggested as potential bioindicators of ocean acidification owing to their sensitivity to acidification in both the laboratory and the natural environment. Using five CO₂ exposure experiments, occurring across four seasons and running for up to 15 days, we describe a consistent relationship between saturation state, shell transparency and duration of exposure, as well as identify a suite of genes that could be used for biological monitoring with further study. We clarify variations in thecosome responses due to seasonality, resolving prior uncertainties and demonstrating the range of their phenotypic plasticity. These biomarkers of acidification stress can be implemented into ecosystem models and monitoring programmes in regions where pteropods are found, whilst the approach will serve as an example for other regions on how to bridge the gap between point-based chemical monitoring and biologically relevant assessments of ecosystem health.

The field of marine mammal conservation has dramatically benefited from the rapid advancement of methods to assess the reproductive physiology of individuals and populations from steroid hormones isolated from minimally invasive skin-blubber biopsy samples. Historically, this vital information was only available from complete anatomical and physiological investigations of samples collected during commercial or indigenous whaling. Humpback whales (Megaptera novaeangliae) are a migratory, cosmopolitan species that reproduce in warm, low-latitude breeding grounds. New Caledonia is seasonally visited by a small breeding sub-stock of humpback whales, forming part of the endangered Oceania subpopulation. To better understand the demographic and seasonal patterns of reproductive physiology in humpback whales, we quantified baseline measurements of reproductive hormones (progesterone-P4, testosterone-T and 17β-estradiol-E2) using an extensive archive of skin-blubber biopsy samples collected from female humpback whales in New Caledonia waters between 2016 and 2019 (n = 194). We observed significant differences in the P4, T and E2 concentrations across different demographic groups of female humpback whales, and we described some of the first evidence of the endocrine patterns of estrous in live free-ranging baleen whales. This study is fundamental in its methodological approach to a wild species that has a global distribution, with seasonally distinct life histories. This information will assist in monitoring, managing and conserving this population as global ecological changes continue to occur unhindered.

Soil microbial inoculants are increasingly being explored as means to improve soil conditions to facilitate ecological restoration. In southwestern Western Australia, highly biodiverse Banksia woodland plant communities are increasingly threatened by various factors including climate change, land development and mining. Banksia woodland restoration is necessary to conserve this plant community. The use of microbial inoculation in Banksia woodland restoration has not yet been investigated. Here, we evaluated the efficacy of a commercial microbial inoculant (GOGO Juice, Neutrog Australia Pty Ltd) for improving the performance of 10 ecologically diverse Banksia woodland plant species in a pot experiment. Plants were subjected to one of two watering regimes (well-watered and drought) in combination with microbial inoculation treatments (non-inoculated and inoculated). Plants were maintained under these two watering treatments for 10 weeks, at which point plants in all treatments were subjected to a final drought period lasting 8 weeks. Plant performance was evaluated by plant biomass and allocation, gas exchange parameters, foliar carbon and nitrogen and stable isotope (δ¹⁵N and δ¹³C) compositions. Plant xylem sap phytohormones were analysed to investigate the effect of microbial inoculation on plant phytohormone profiles and potential relationships with other observed physiological parameters. Across all investigated plant species, inoculation treatments had small effects on plant growth. Further analysis within each species revealed that inoculation treatments did not result in significant biomass gain under well-watered or drought-stressed conditions, and effects on nitrogen nutrition and photosynthesis were variable and minimal. This suggests that the selected commercial microbial inoculant had limited benefits for the tested plant species. Further investigations on the compatibility between the microorganisms (present in the inoculant) and plants, timing of inoculation, viability of the microorganisms and concentration(s) required to achieve effectiveness, under controlled conditions, and field trials are required to test the feasibility and efficacy in actual restoration environments.

Thermal stress can influence the recovery of fish released after capture. Vitality assessments using reflex and behavioural responses require that responses can be observed reliably, independent of temperature. Here, we tested whether reflex and behavioural impairment and survival of beam-trawled and discarded European plaice (Pleuronectes platessa) are independent from seasonal air and water temperature deviations. In total, 324 beam-trawled plaice (n = 196 in summer and n = 128 in winter) were exposed to two air temperature treatments and two water treatments (i.e. modified and ambient temperatures for both). The modified treatments (i.e. cooled in summer, warmed in winter) represent the thermal shock a fish may experience when being returned to the water. All reflexes and tested behaviours were affected by ambient temperature, with high impairment noted in summer. None of the reflexes were affected by temperature shocks alone, only body flex was. Body flex was highly impaired under every exposure combination. Fish size and duration of air exposure further influenced impairment of reflexes such as head complex and tail grab. More generally, post-release survival was assessed as 21% [95% CI: 16-28%] in summer and 99% [97-100%] in winter. Beam trawling in summer is likely to induce high reflex impairment and mortality in discarded plaice, and therefore spatial-temporal mitigation approaches should be prioritized over control of on-board temperatures.

Animals face several challenges in their natural environment, and to cope with such conditions, they may exhibit contrasting physiological responses that directly affect their overall well-being and survival. In this study, we assessed physiological responses via faecal glucocorticoid metabolite (fGCM) measurements in free-ranging mugger crocodiles inhabiting diverse habitats in Gujarat, India. We sampled muggers within Charotar, a rural area (Zone A) with local people having high tolerance towards the presence of muggers, and Vadodara, a region having both urban (Zone B) and rural (Zone C) areas with high levels of human-mugger conflict (HMC). Further, muggers in Vadodara live in water bodies that are mostly polluted due to sewage disposal from adjoining chemical industries. To measure fGCM (mean ± SEM, ng/g dry faeces) levels in muggers, scats were collected during both breeding (N = 107 scats) and non-breeding (N = 22 scats) seasons from all three zones. We used captive muggers (a focal enclosure) to biologically validate (via capture and restraint) the selected fGCM assay (11-oxoetiocholanolone assay). We showed a significant (P < 0.05) 11-fold increase in fGCM levels between pre-capture (540.9 ± 149.2, N = 11) and post-capture (6259.7 ± 1150.5, N = 11) samples. The validated assay was applied to free-ranging muggers during the breeding season, and Zone A showed significantly (P < 0.05) lower fGCM levels (542.03 ± 71.3) compared to muggers of Zone B (1699.9 ± 180.8) and Zone C (1806.4 ± 243.2), both zones having high levels of HMC with polluted water bodies. A similar contrast in fGCM levels was also observed during the non-breeding season. Overall, the study demonstrated that fGCM levels in muggers varied across habitats, and such variation could be due to a multitude of ecological factors that the species experience in their immediate local environment. Moreover, high fGCM levels in muggers of Vadodara during both breeding and non-breeding seasons may indicate a condition of chronic stress, which could be maladaptive for the species.