Conservation Physiology最新文献

As part of its mission to advance the field of wildlife endocrinology, the International Society of Wildlife Endocrinology aims to develop cost-effective antibodies and enzyme immunoassay kits that support research across a diverse range of species and sample matrices. To provide additional options for the quantification of faecal glucocorticoid metabolites (fGCMs), an antibody against 11-oxoetiocholanolone-17-carboxymethyl oxime (CMO) was generated in rabbits, and an enzyme immunoassay incorporating a horseradish peroxidase-conjugated label and 11-oxoetiocholanolone standard has been developed, designed for use with anti-rabbit IgG secondary antibody coated plates. This mini-kit was used to quantify glucocorticoid metabolites with a 5β-3α-ol-11-one structure in faecal extracts from 23 species: African and Asian elephants, Alpine chamois, American bison, Bengal tiger, blue wildebeest, blue-and-yellow macaw, brushtail possum, cape buffalo, fat-tailed dunnart, Florida manatee, ghost bat, giraffe, golden langur, Gould's wattled bat, hippopotamus, Leadbeater's possum, mandrill, okapi, roan antelope, samango monkey, short-beaked echidna, and western lowland gorilla. Pharmacological (adrenocorticotropic hormone challenge) and biological (inter-zoo translocation, wild capture, social disruption, illness/injury and veterinary intervention) challenges resulted in expected increases in fGCM concentrations, and in a subset of species, closely paralleled results from a previously established immunoassay against 11-oxoetiocholanolone-17-CMO. Two additional species tested, Krefft's glider, which showed contradictory results on this assay compared to a previously validated enzyme immunoassay (EIA) and Ankole cow, where the magnitude increase post-event did not quite reach the 2-fold change criteria, highlight that differences in excreted faecal metabolites across species mean that no EIA will be suitable for all species. This assay provides a valuable new option for assessing adrenal activity across taxa using a group-specific antibody. Future studies should put similar emphasis on validation to determine optimal assay choice for measuring fGCMs in a variety of species.

Manually obtaining the length and other morphometric features of an animal can be time-consuming, and consistent measurements are challenging with large datasets. By leveraging high-throughput computing power and machine learning-based computer vision, such phenotypic data can be rapidly collected with high accuracy. Here we present HusMorph, a novel application with a simple and intuitive graphical user interface (GUI), based on the same machine learning method used in other pipelines such as ML-morph. It consists of an all-in-one package with the goal of making machine learning easy to use for non-experts. The user starts by setting any number of landmarks on a set of photos captured with a standardized setup. From this set, a machine learning model is generated by automatically and randomly searching for the best performing parameters. Next, the user can apply the model to predict landmarks on new standardized photos and visually confirm and export the results of the predictions. For measuring length between landmarks, an additional feature allows for detecting a scale bar for each photo to convert the length from pixels to a metric unit. Our application has been validated and applied to extract standard length from 1935 photos of zebrafish and performs with ~99.5% accuracy compared to manual measurements.

Estuarine environments are characterized by fluctuating abiotic conditions, such as salinity and oxygen partial pressure, which challenge the physiological systems of resident species. Organisms inhabiting these systems have evolved physiological plasticity to cope with this variability, particularly in relation to oxygen availability. Estuarine species tend to exhibit greater hypoxia tolerance compared to coastal marine species, likely due to periodic low oxygen exposure. However, the effects of salinity fluctuations on oxygen transport remains unclear. This study investigated the effects of different salinity levels on the oxygen supply capacity of the Atlantic stingray (Hypanus sabinus), a euryhaline elasmobranch in the temperate west Atlantic and Gulf of Mexico. Maximum metabolic rates and oxygen supply capacity were measured at high, medium and low salinities (32, 16 and 6 psu, respectively). Critical oxygen pressure (P _cMax), where maximum metabolism and aerobic scope become oxygen limited, was also calculated. Results showed a significant 20% increase in oxygen supply capacity and a 30% decrease in P _cMax under low salinity compared to high salinity. These findings suggest that Atlantic stingrays improve their oxygen supply capacity and are more hypoxia tolerant in hyposaline conditions. Enhanced oxygen supply capacity may represent an adaptive strategy, enabling Atlantic stingrays to maintain metabolic performance in low oxygen environments. This study provides novel insight into the adaptive capacity of euryhaline elasmobranchs to balance oxygen transport and metabolic function across salinity gradients. It highlights the importance of physiological plasticity in estuarine species' responses to climate-driven changes in salinity and oxygen availability. These findings can inform management strategies by identifying species with greater resilience to hypoxia and salinity shifts, supporting more effective conservation efforts under future climate scenarios.

For aerial insectivorous birds, whose populations have declined significantly in North America, long-chain polyunsaturated fatty acids (LC-PUFA) that are more abundant in aquatic-emergent insects than terrestrial insects, are important for the development, somatic growth, and health of young birds. Some bird species, however, can convert shorter chain PUFA that occur abundantly in terrestrial insects into LC-PUFA. Our study aimed to evaluate the ability of two aerial insectivore species to synthesize their own LC-PUFA. We hypothesized that terrestrially associated aerial insectivores rely on higher fatty acid conversion rates compared to those associated with wetlands and riparian habitats. We fed wild barn swallow (Hirundo rustica) and purple martin (Progne subis) nestlings ¹³C-labelled essential omega-3 (α-linolenic acid; ALA) or omega-6 (linoleic acid; LA) fatty acids to trace internal fatty acid conversion from these dietary precursors. Using compound-specific stable isotope measurements of livers, we estimated conversion efficiency to LC-PUFA. Barn swallow nestlings converted 76% of the omega-3 ALA and 46% of the omega-6 LA precursors to LC-PUFA. Purple martin nestlings converted 88% of the ALA and 44% of the LA. Both species converted five times more ALA to DHA than previously reported in tree swallows (Tachycineta bicolor) and may be more adapted to fluctuations in diet quality and habitat types. Our research highlights the variability in conversion efficiency within the guild of aerial insectivores and the need to better understand which species may be less resilient to sudden changes in nutritional landscapes.

Faecal hormone metabolite (FHM) analyses are increasingly used as a non-invasive method to evaluate physiological stress in wild populations, especially those of conservation concern. In cetaceans, faecal collection from the ocean surface results in considerable variation in sample volume and density. Knowledge of the distribution of hormone metabolites within a faecal sample is limited, but is an important consideration when interpreting values. Here we investigated the variability of glucocorticoid (fGCM) and thyroid (fTHM) metabolites within fish-eating resident killer whale faeces by comparing mean concentration, standard deviation (SD) and coefficient of variation (CV) among three treatment groups: sub-samples, pooled sub-samples and homogenized pooled sub-samples from the same defecation event. No significant difference was found in the mean concentration of fGCM and fTHM across treatment groups. The mean SD for fGCM was significantly higher in sub-samples than in pooled and homogenized treatment groups (P < 0.05), while differences in the mean SD of fTHM were not significant among treatment groups. Overall, the CV of FHM measurements was reduced to less than 15% and 10%, respectively, by pooling and homogenizing the sub-samples prior to analysis. We found high correlation in fGCM and fTHM across all treatments, suggesting that values from sub-samples were generally representative of the overall faecal sample. These findings help guide methods for processing cetacean faecal samples and interpreting associated FHM data.

The green sea turtle (Chelonia mydas), a globally endangered marine reptile, faces significant population declines due to anthropogenic and environmental pressures. Captive rehabilitation programs are critical for conservation, yet captivity-induced physiological deviations may compromise post-release survival. This study establishes haematological and biochemical reference intervals for pre-release captive C. mydas (n = 40) various across juvenile, subadult, and adult life stages, and identifies key deviations from wild baselines. We found pronounced captivity-specific alterations, including elevated immature red blood cell counts and ghost cell counts in juveniles, which indicated dysregulated erythropoiesis and oxidative stress. Ontogenetic shifts revealed maladaptive macrocytic erythrocytosis in adults, likely linked to limited exercise and dietary imbalances. Biochemically, captive adults showed hyperproteinemia (total protein, 73.35 g/l) and dyslipidemia (total cholesterol, 8.98 mmol/l triglycerides, 1.53 mmol/l), indicating high-protein, high-fat diets, while hypoglucagonemia (glucose, 2.83 mmol/l) suggested compromised energy reserves. Age-dependent immune activity was observed, with juveniles exhibiting elevated leukocyte counts (19.34 × 10⁹/l), potentially due to chronic stress. These findings underscore metabolic and haematological adaptations in captivity that may hinder post-release resilience. Key biomarkers, such as immature red cell count, glucose, and lipid profiles, should guide release readiness assessments, thus ensuring rehabilitated turtles are physiologically primed for survival. This study provides a critical framework for enhancing the efficacy of sea turtle conservation translocations.

The blue shark (Prionace glauca) is the most frequently by-caught species in longline fisheries targeting swordfish in the Mediterranean Sea. The IUCN classifies the Mediterranean blue shark population as critically endangered, but no information on haematological or biochemical parameters is available for this population. Based on a multi-year dataset of 63 blue sharks (Prionace glauca) and 18 physiological parameters, this study provides the first detailed insights into the variability of physiological indicators following bycatch in the Mediterranean Sea. We also examined differences across three post-capture condition groups and assessed the potential influence of sex and life stage (juvenile vs. adult) on physiological variability. While no significant differences emerged between sexes or life stages, clear distinctions were observed between condition groups, particularly when compared to moribund or dead individuals (condition group 3). These sharks showed signs of enhanced physiological stress, including reduced glucose, elevated lactate, and altered osmoregulatory function (lower urea and chloride, higher phosphorus). These patterns align with stress responses previously described in other shark species. Overall, the study provides a valuable baseline for future research into the physiology and conservation of Mediterranean blue sharks' population.

Aquaculture plays a crucial role in global food security and is being increasingly used to aid species and ecosystem conservation. However, concerns over environmental impact of aquaculture expansion are driving research into ecosystem approaches to aquaculture. Ecosystem approaches to aquaculture require understanding of the relationship between aquafeeds and aquaculture species to maximize consumer growth, quantify elemental flow of nutrients and minimize waste output. Conventional bioenergetic models typically assume fixed elemental ratios to quantify metabolic processes and do not consider an organism's nutrient demand. A new bridging framework, Geometric Stoichiometry (GS), unifies nutritional geometry and ecological stoichiometry disciplines using macromolecules as currencies and dietary regulation to balance nutrient deficits and excesses by the consumer. We present the first application of the GS framework to aquaculture by investigating how different formulated feed ingredients affect intakes to maintain C:N homeostasis, growth and waste output using three opportunistic datasets for an emerging aquaculture species, slipper lobster (Thenus australiensis). Our GS model results indicate that protein sources and their inclusion levels drive the most variation in feed intake and growth. It also predicts highest nitrogenous waste for fish meal and lowest for squid by-product meal feeds. Our results highlight the need for targeted experiments to further refine the GS model to help support environmental management and formulate low-impact feeds for aquaculture.