Behaviour is more important than thermal performance for an Arctic host-parasite system under climate change.

Climate change is affecting Arctic ecosystems, including parasites. Predicting outcomes for host-parasite systems is challenging due to the complexity of multi-species interactions and the numerous, interacting pathways by which climate change can alter dynamics. Increasing temperatures may lead to faster development of free-living parasite stages but also higher mortality. Interactions between behavioural plasticity of hosts and parasites will also influence transmission processes. We combined laboratory experiments and population modelling to understand the impacts of changing temperatures on barren-ground caribou (Rangifer tarandus) and their common helminth (Ostertagia gruehneri). We experimentally determined the thermal performance curves for mortality and development of free-living parasite stages and applied them in a spatial host-parasite model that also included behaviour of the parasite (propensity for arrested development in the host) and host (long-distance migration). Sensitivity analyses showed that thermal responses had less of an impact on simulated parasite burdens than expected, and the effect differed depending on parasite behaviour. The propensity for arrested development and host migration led to distinct spatio-temporal patterns in infection. These results emphasize the importance of considering behaviour-and behavioural plasticity-when projecting climate-change impacts on host-parasite systems.

Metabolic approaches to understanding climate change impacts on seasonal host-macroparasite dynamics.

Climate change is expected to alter the dynamics of infectious diseases around the globe. Predictive models remain elusive due to the complexity of host-parasite systems and insufficient data describing how environmental conditions affect various system components. Here, we link host-macroparasite models with the Metabolic Theory of Ecology, providing a mechanistic framework that allows integrating multiple nonlinear environmental effects to estimate parasite fitness under novel conditions. The models allow determining the fundamental thermal niche of a parasite, and thus, whether climate change leads to range contraction or may permit a range expansion. Applying the models to seasonal environments, and using an arctic nematode with an endotherm host for illustration, we show that climate warming can split a continuous spring-to-fall transmission season into two separate transmission seasons with altered timings. Although the models are strategic and most suitable to evaluate broad-scale patterns of climate change impacts, close correspondence between model predictions and empirical data indicates model applicability also at the species level. As the application of Metabolic Theory considerably aids the a priori estimation of model parameters, even in data-sparse systems, we suggest that the presented approach could provide a framework for understanding and predicting climatic impacts for many host-parasite systems worldwide.

Obligate larval inhibition of Ostertagia gruehneri in Rangifer tarandus? Causes and consequences in an Arctic system.

Larval inhibition is a common strategy of Trichostrongylidae nematodes that may increase survival of larvae during unfavourable periods and concentrate egg production when conditions are favourable for development and transmission. We investigated the propensity for larval inhibition in a population of Ostertagia gruehneri, the most common gastrointestinal Trichostrongylidae nematode of Rangifer tarandus. Initial experimental infections of 4 reindeer with O. gruehneri sourced from the Bathurst caribou herd in Arctic Canada suggested that the propensity for larval inhibition was 100%. In the summer of 2009 we infected 12 additional reindeer with the F1 and F2 generations of O. gruehneri sourced from the previously infected reindeer to further investigate the propensity of larval inhibition. The reindeer were divided into 2 groups and half were infected before the summer solstice (17 June) and half were infected after the solstice (16 July). Reindeer did not shed eggs until March 2010, i.e. 8 and 9 months post-infection. These results suggest obligate larval inhibition for at least 1 population of O. gruehneri, a phenomenon that has not been conclusively shown for any other trichostrongylid species. Obligate inhibition is likely to be an adaptation to both the Arctic environment and to a migratory host and may influence the ability of O. gruehneri to adapt to climate change.

Parasites in ungulates of Arctic North America and Greenland: a view of contemporary diversity, ecology, and impact in a world under change.

Parasites play an important role in the structure and function of arctic ecosystems, systems that are currently experiencing an unprecedented rate of change due to various anthropogenic perturbations, including climate change. Ungulates such as muskoxen, caribou, moose and Dall's sheep are also important components of northern ecosystems and are a source of food and income, as well as a focus for maintenance of cultural traditions, for northerners. Parasites of ungulates can influence host health, population dynamics and the quality, quantity and safety of meat and other products of animal origin consumed by people. In this article, we provide a contemporary view of the diversity of nematode, cestode, trematode, protozoan and arthropod parasites of ungulates in arctic and subarctic North America and Greenland. We explore the intricate associations among host and parasite assemblages and identify key issues and gaps in knowledge that emerge in a regime of accelerating environmental transition.

Development and availability of the free-living stages of Ostertagia gruehneri, an abomasal parasite of barrenground caribou (Rangifer tarandus groenlandicus), on the Canadian tundra.

Climate change in the Arctic is anticipated to alter the ecology of northern ecosystems, including the transmission dynamics of many parasite species. One parasite of concern is Ostertagia gruehneri, an abomasal nematode of Rangifer ssp. that causes reduced food intake, weight loss, and decreased pregnancy rates in reindeer. We investigated the development, availability, and overwinter survival of the free-living stages of O. gruehneri on the tundra. Fecal plots containing O. gruehneri eggs were established in the Northwest Territories, Canada under natural and artificially warmed conditions and sampled throughout the growing season of 2008 and the spring of 2009. Infective L3 were present 3-4 weeks post-establishment from all trials under both treatments, except for the trial established 4 July 2008 under warmed conditions wherein the first L3 was recovered 7 weeks post-establishment. These plots were exposed to significantly more time above 30°C than the natural plots established on the same date, suggesting a maximum temperature threshold for development. There was high overwinter survival of L2 and L3 across treatments and overwintering L2 appeared to develop to L3 the following spring. The impact of climate change on O. gruehneri is expected to be dynamic throughout the year with extreme maximum temperatures negatively impacting development rates.

Campylobacter canadensis sp. nov., from captive whooping cranes in Canada.

Ten isolates of an unknown Campylobacter species were isolated from cloacal swabs obtained from captive adult whooping cranes (Grus americana). All isolates were identified as Campylobacter based on generic PCR and grouped with other Campylobacter species based on 23S rRNA gene sequence. None of the isolates could be identified by species-specific PCR for known taxa, and all ten isolates formed a robust clade that was very distinct from known Campylobacter species based on 16S rRNA, rpoB and cpn60 gene sequences. The results of 16S rRNA gene nucleotide sequence (

Evaluation of the enteric microflora of captive whooping cranes (Grus americana) and sandhill cranes (Grus canadensis).

The enteric flora of captive whooping cranes (Grus americana) and sandhill cranes (Grus canadensis) has not been well described, despite its potential importance in the understanding of both the normal condition of the intestinal physiology of these animals and the altered colonization within disease states in these birds. Nineteen whooping cranes and 23 sandhill cranes housed currently at the Calgary Zoo or its affiliated Devonian Wildlife Conservation Centre (DWCC) in Calgary, Alberta were sampled from October 2004-February 2005 by collecting aerobic and anaerobic cloacal swabs from each bird. There were seven major groupings of bacteria isolated from both species of crane. Gram-positive cocci, coliforms, and gram-negative bacilli were the most prevalent types of bacteria isolated for both crane species, with Escherichia coli, Enterococcus faecalis, and Streptococcus Group D, not Enterococcus the bacterial species isolated most commonly. There was a significant difference in the average number of isolates per individual between the two crane species but no differences between age or gender categories within crane species. Campylobacter sp. were isolated from five whooping cranes. The potential zoonotic pathogen Campylobacter jejuni was isolated from one whooping crane and C. upsaliensis was isolated from a second. Three other isolates were unspeciated members of the Campylobacter genus and likely belong to a species undescribed previously. The evaluation of the enteric cloacal flora of whooping cranes and sandhill cranes illustrates that differences exist between these two closely related crane species, and highlights the potential implications these differences may have for current practices involving captive wildlife. Zoo Biol 0:1-13, 2007. (c) 2007 Wiley-Liss, Inc.