Detecting changes in the annual movements of terrestrial migratory species : using the first-passage time to document the spring migration of caribou

Background : Migratory species face numerous threats related to human encroachment and climate change. Several migratory populations are declining and individuals are losing their migratory behaviour. To understand how habitat loss or changes in the phenology of natural processes affect migrations, it is crucial to clearly identify the timing and the patterns of migration. We propose an objective method, based on the detection of changes in movement patterns, to identify departure and arrival dates of the migration. We tested the efficiency of our approach using simulated paths before applying it to spring migration of migratory caribou from the Rivière-George and Rivière-aux-Feuilles herds in northern Québec and Labrador. We applied the First-Passage Time analysis (FPT) to locations of 402 females collected between 1986 and 2012 to characterize their movements throughout the year. We then applied a signal segmentation process in order to segment the path of FPT values into homogeneous bouts to discriminate migration from seasonal range use. This segmentation process was used to detect the winter break and the calving ground use because spring migration is defined by the departure from the winter range and the arrival on the calving ground. Results : Segmentation of the simulated paths was successful in 96% of the cases, and had a high precision (96.4% of the locations assigned to the appropriate segment). Among the 813 winter breaks and 669 calving ground use expected to be detected on the FPT profiles, and assuming that individuals always reduced movements for each of the two periods, we detected 100% of the expected winter breaks and 89% of the expected calving ground use, and identified 648 complete spring migrations. Failures to segment winter breaks or calving ground use were related to individuals only slowing down or performing less pronounced pauses resulting in low mean FPT. Conclusion : We show that our approach, which relies only on the analysis of movement patterns, provides a suitable and easy-to-use tool to study species exhibiting variations in their migration patterns and seasonal range use

Determinants of migration trajectory and movement rate in a long-distance terrestrial mammal

Animal migrations occur in many taxa and are considered an adaptive response to spatial or temporal variations in resources. Human activities can influence the cost-benefit trade-offs of animal migrations, but evaluating the determinants of migration trajectory and movement rate in declining populations facing relatively low levels of human disturbance can provide new and valuable insights on the behavior of wildlife in natural environments. Here, we used an adapted version of path selection functions and quantified the effects of habitat type, topography, and weather, on 313 spring migrations by migratory caribou (Rangifer tarandus) in northern Québec, Canada, from 2011 to 2018. Our results showed that during spring migration, caribou selected tundra and avoided water bodies, forest, and higher elevation. Higher precipitation and deeper snow were linked to lower movement rates. Weather variables had a stronger effect on the migration trajectories and movement rates of females than males. Duration of caribou spring migration (mean of 48 days) and length (mean of 587 km) were similar in males and females, but females started (22 April) and ended (10 June) spring migrations ca. 6 days earlier than males. Caribou spring migration was influenced by habitat type, topography, and weather, but we also observed that caribou migrations were not spatially constrained. Better knowledge on where and when animals move between their winter and summer ranges can help inform management and land planning decisions. Our results could be used to model future migration trajectories and speed of caribou under different climate change scenarios

Temporally dynamic habitat suitability predicts genetic relatedness among caribou

Landscape heterogeneity plays a central role in shaping ecological and evolutionary processes. While species utilization of the landscape is usually viewed as constant within a year, the spatial distribution of individuals is likely to vary in time in relation to particular seasonal needs. Understanding temporal variation in landscape use and genetic connectivity has direct conservation implications. Here, we modelled the daily use of the landscape by caribou in Quebec and Labrador, Canada and tested its ability to explain the genetic relatedness among individuals. We assessed habitat selection using locations of collared individuals in migratory herds and static occurrences from sedentary groups. Connectivity models based on habitat use outperformed a baseline isolation-by-distance model in explaining genetic relatedness, suggesting that variations in landscape features such as snow, vegetation productivity and land use modulate connectivity among populations. Connectivity surfaces derived from habitat use were the best predictors of genetic relatedness. The relationship between connectivity surface and genetic relatedness varied in time and peaked during the rutting period. Landscape permeability in the period of mate searching is especially important to allow gene flow among populations. Our study highlights the importance of considering temporal variations in habitat selection for optimizing connectivity across heterogeneous landscape and counter habitat fragmentation

Caribou herd dynamics : impacts of climate change on traditional and sport harvesting

Caribou (Rangifer tarandus) are a key species in Arctic ecosystems including northern Québec and Labrador. They play a central role in the ecology of predators and the structure of Arctic plant communities. In addition, caribou provide socioeconomic and cultural benefits from subsistence and sport hunting activities. Changes in the distribution and abundance of caribou due to global climate change would have serious biological, societal, and economic implications. Direct and indirect consequences of climate change on migratory caribou herds may include alteration in habitat use, migration patterns, foraging behaviour and demography. For example, caribou may experience a further northerly shift in distribution due to several factors including longer ice-free periods, increases in snowfall and extreme weather events, alterations in the fire regime, and changes in the distribution of insects and predators. Future research by Caribou Ungava, a research group interested in the ecology of migratory caribou in the context of climate change, will address the factors outlining variations in the population dynamics of caribou, implications for survival and reproduction, as well as the response of caribou habitat to different climate change scenarios. Management efforts focusing on mitigating greenhouse gases to reduce the potential effects of climate change, preserving high quality habitat, limiting anthropogenic landscape disturbances, and managing hunting in a sustainable manner, could alleviate stressors on migratory caribou of the QuébecLabrador peninsula

Compromised cerebrovascular regulation and cerebral oxygenation in pulmonary arterial hypertension

Background : Functional cerebrovascular regulatory mechanisms are important for maintaining constant cerebral blood flow and oxygen supply in heathy individuals and are altered in heart failure. We aim to examine whether pulmonary arterial hypertension (PAH) is associated with abnormal cerebrovascular regulation and lower cerebral oxygenation and their physiological and clinical consequences. Methods and Results : Resting mean flow velocity in the middle cerebral artery mean flow velocity in the middle cerebral artery (MCAvmean); transcranial Doppler), cerebral pressure‐flow relationship (assessed at rest and during squat‐stand maneuvers; analyzed using transfer function analysis), cerebrovascular reactivity to CO2, and central chemoreflex were assessed in 11 patients with PAH and 11 matched healthy controls. Both groups also completed an incremental ramp exercise protocol until exhaustion, during which MCAvmean, mean arterial pressure, cardiac output (photoplethysmography), end‐tidal partial pressure of CO2, and cerebral oxygenation (near‐infrared spectroscopy) were measured. Patients were characterized by a significant decrease in resting MCAvmean (P<0.01) and higher transfer function gain at rest and during squat‐stand maneuvers (both P<0.05). Cerebrovascular reactivity to CO2 was reduced (P=0.03), whereas central chemoreceptor sensitivity was increased in PAH (P<0.01), the latter correlating with increased resting ventilation (R2=0.47; P<0.05) and the exercise ventilation/CO2 production slope (Embedded Image slope; R2=0.62; P<0.05) during exercise for patients. Exercise‐induced increases in MCAvmean were limited in PAH (P<0.05). Reduced MCAvmean contributed to impaired cerebral oxygen delivery and oxygenation (both P<0.05), the latter correlating with exercise capacity in patients with PAH (R2=0.52; P=0.01). Conclusions : These findings provide comprehensive evidence for physiologically and clinically relevant impairments in cerebral hemodynamic regulation and oxygenation in PAH

Shelled pteropods in peril: Assessing vulnerability in a high CO2 ocean

The impact of anthropogenic ocean acidification (OA) on marine ecosystems is a vital concern facing marine scientists and managers of ocean resources. Euthecosomatous pteropods (holoplanktonic gastropods) represent an excellent sentinel for indicating exposure to anthropogenic OA because of the sensitivity of their aragonite shells to the OA conditions less favorable for calcification. However, an integration of observations, experiments and modelling efforts is needed to make accurate predictions of how these organisms will respond to future changes to their environment. Our understanding of the underlying organismal biology and life history is far from complete and must be improved if we are to comprehend fully the responses of these organisms to the multitude of stressors in their environment beyond OA. This review considers the present state of research and understanding of euthecosomatous pteropod biology and ecology of these organisms and considers promising new laboratory methods, advances in instrumentation (such as molecular, trace elements, stable isotopes, palaeobiology alongside autonomous sampling platforms, CT scanning and high-quality video recording) and novel field-based approaches (i.e. studies of upwelling and CO2 vent regions) that may allow us to improve our predictive capacity of their vulnerability and/or resilience. In addition to playing a critical ecological and biogeochemical role, pteropods can offer a significant value as an early-indicator of anthropogenic OA. This role as a sentinel species should be developed further to consolidate their potential use within marine environmental management policy making

Péritonites communautaires et nosocomiales (identification de facteurs de multirésistance bactérienne)

RENNES1-BU Santé (352382103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Le psychodrame psychanalytique de groupe pour adolescents : une machine à explorer le temps ?

International audienceBy having adolescents experiment with games concerning time, group psychoanalytic psychodrama may lead to the construction of a shareable group past. A session offering a machine to explore time and rediscover the lost time of holidays illustrates this tool’s substantial therapeutic potential.Le psychodrame psychanalytique de groupe pour adolescents en faisant expérimenter des jeux autour de la temporalité peut parvenir à construire un passé groupal partageable. Une séance mettant en scène une machine à explorer le temps pour retrouver le temps perdu des vacances illustre le formidable potentiel thérapeutique de ce dispositif