Tempo-spatial patterns of PM2.5 measured using a portable particulate monitor around a mine complex in Canada's Arctic.

Mining activities in Canada's pristine Arctic (e.g., driving on unpacked roads, blasts, rock grinding, diesel combustion, and garbage incineration) could add local sources of airborne fine particulate matter with a diameter of < 2.5 µm (PM2.5) to their surrounding area. The increase in PM2.5 above the background level around a mine represents a potential disturbance to caribou. To quantify the spatial distribution of the elevated PM2.5, we investigated three different sampling schemes to measure PM2.5 concentration using a portable monitor. We found that the best sampling scheme was to use the regional background PM2.5 as the reference and analyze the anomaly of PM2.5 measured at sites around the mine complex from the background level. The regional background PM2.5 values were measured at the Daring Lake Tundra Research Station during 2018 and 2019. Our results indicated that the background PM2.5 was not a low and constant value but varied with rain events, wind direction, and the impacts of forest fire smoke. After excluding periods affected by forest fires smokes, we found the background PM2.5 was close to 0 µg m-3 for the first few hours after rain, and then increased logistically with the time after rain (tar) to the maximum of 5 (or 10) µg m-3 when the wind came from the north (or south) of the NW-SE axis. The NW-SE axis in western Canada divides the tundra north with few anthropogenic PM2.5 sources from the forested south with many PM2.5 sources from forest fire smokes and human activities. Analyses of PM2.5 anomaly from the background (i.e., PM2.5 measured at a site around the mining complex-the background level at the corresponding tar and wind direction) revealed that the zone of elevated PM2.5 around the mine (Zepm) expanded with tar. In the first few hours after rain, PM2.5 was close to 0 everywhere except within meters of a source (e.g., a truck exhaust) in the downwind direction. During tar = 6 to 96 h, Zepm expanded to 6.3 km in the downwind direction when the wind came from south of the NW-SE axis. A similar result was found in the downwind direction when the wind came from north of the NW-SE axis, with Zepm = 4.4 km. In the upwind direction, the value of Zepm was much smaller, being 0.7 km (or 1.0 km) when the wind came from the north (or south) of the NW-SE axis. For the period of tar between 96 and 192 hours, Zepm further expanded to 21.2 km when the wind from the south of the NW-SE axis. The results from this study indicated that this reference paradigm that uses the regional background PM2.5 as the reference in combination with a portable PM2.5 monitor worked well for quantifying the tempo-spatial patterns of PM2.5 at locations in remote and mostly pristine Arctic. However, their effectiveness for other regions needs further investigation.

Gauging climate change effects at local scales: weather-based indices to monitor insect harassment in caribou.

Climate change is occurring at an accelerated rate in the Arctic. Insect harassment may be an important link between increased summer temperature and reduced body condition in caribou and reindeer (both Rangifer tarandus). To examine the effects of climate change at a scale relevant to Rangifer herds, we developed monitoring indices using weather to predict activity of parasitic insects across the central Arctic. During 2007-2009, we recorded weather conditions and used carbon dioxide baited traps to monitor activity of mosquitoes (Culicidae), black flies (Simuliidae), and oestrid flies (Oestridae) on the post-calving and summer range of the Bathurst barren-ground caribou (Rangifer tarandus groenlandicus) herd in Northwest Territories and Nunavut, Canada. We developed statistical models representing hypotheses about effects of weather, habitat, location, and temporal variables on insect activity. We used multinomial logistic regression to model mosquito and black fly activity, and logistic regression to model oestrid fly presence. We used information theory to select models to predict activity levels of insects. Using historical weather data, we used hindcasting to develop a chronology of insect activity on the Bathurst range from 1957 to 2008. Oestrid presence and mosquito and black fly activity levels were explained by temperature. Wind speed, light intensity, barometric pressure, relative humidity, vegetation, topography, location, time of day, and growing degree-days also affected mosquito and black fly levels. High predictive ability of all models justified the use of weather to index insect activity. Retrospective analyses indicated conditions favoring mosquito activity declined since the late 1950s, while predicted black fly and oestrid activity increased. Our indices can be used as monitoring tools to gauge potential changes in insect harassment due to climate change at scales relevant to caribou herds.

Comparison of gross visual and microscopic assessment of four anatomic sites to monitor Besnoitia tarandi in barren-ground caribou (Rangifer tarandus).

The objective of this study was to establish a standardized protocol to monitor Besnoitia tarandi prevalence and intensity in barren-ground caribou (Rangifer tarandus) herds by: 1) calculating the relative sensitivity and specificity of the gross visual assessment of four anatomical sites compared with microscopic evaluation, and 2) determining which of four anatomical sampling sites was the most sensitive for detecting B. tarandi cysts by microscopy. Sampled tissues consisted of the conjunctiva of the left eye and skin sections from the rostrum, metatarsus, and thigh from 312 harvested caribou. Diagnosis of infection with B. tarandi was based on observation of at least one cyst by microscopic examination. For each tissue, the maximal density of cysts (number of B. tarandi cysts/mm(2) in the section examined) was calculated for a measured area consisting of the dermis extending from the epidermis of the skin to the base of the hair follicles and adnexal structures. For the conjunctiva, the entire submucosa was evaluated. Gross visual evaluation markedly underestimated B. tarandi prevalence in caribou with a relative sensitivity ranging from 0.29 in the conjunctiva to 0.13 in the skin section from the thigh, whereas relative specificities ranged from 0.98 to 1.00. The metatarsus and rostrum skin sections had the highest probabilities of cyst detection of all four anatomical sampling sites. The metatarsus harbored significantly higher densities of B. tarandi cysts than the rostrum, thigh, or conjunctiva. In conclusion, microscopic evaluation of a skin section from the anterior aspect of the mid-third portion of the metatarsal region could be used as a standardized comparative indicator of density of B. tarandi infection in Rangifer.

Behavioural trade-offs in response to external stimuli: time allocation of an Arctic ungulate during varying intensities of harassment by parasitic flies.

1. Macroparasites may be a major factor shaping animal behaviour. Tundra ecosystems inhabited by caribou and reindeer (Rangifer tarandus) are known for large concentrations of ectoparasites including mosquitoes (Culicidae) and black flies (Simuliidae), as well as endoparasitic oestrid flies (Oestridae). 2. Increased intensity and duration of insect harassment because of climatic warming is hypothesized as a potential factor in recent declines of Rangifer across the circumpolar north. Although there is a well-observed relationship between insect harassment and caribou/reindeer behaviour, the influence of ecto- relative to endoparasitic species is unclear. Climatic changes may favour the activity patterns, distribution or abundance of certain insect species; thus, understanding differential effects on the behaviour of Rangifer is important. 3. We recorded caribou behaviour using group scan and focal sampling methods, while simultaneously trapping insects and recording weather conditions on the postcalving/summer range of the Bathurst barren-ground caribou herd in Northwest Territories and Nunavut, Canada, during 2007-2009. 4. We developed statistical model sets representing hypotheses about the effects of insects, weather, habitat/location, and date/time on caribou behaviour. We used multinomial logistic regression models to explore factors affecting the relative dominance of behaviour types within groups of caribou and fractional multinomial logistic regression models to determine factors influencing time allocation by individual caribou. We examined changes in feeding intensity using fractional logistic regression. 5. Relative dominance of insect avoidance behaviour within caribou groups and time allocation to insect avoidance by individual caribou increased when oestrid flies were present or black flies were active at moderate-high levels. Mosquito activity had relatively little effect on caribou behaviour. Time spent feeding was reduced by the greatest degree when all three insect types were present in combination. Feeding intensity was influenced to a greater extent by the accumulation of growing degree days over the course of the postcalving/summer season than by insect activity. Changes in Arctic systems that increase the activity/abundance of ecto- and endoparasites could have implications for the productivity of Rangifer populations.

Subpopulation structure of caribou (Rangifer tarandus L.) in arctic and subarctic Canada.

Effective management and conservation of species, subspecies, or ecotypes require an understanding of how populations are structured in space. We used satellite-tracking locations and hierarchical and fuzzy clustering to quantify subpopulations within the behaviorally different barren-ground caribou (Rangifer tarandus groenlandicus), Dolphin and Union island caribou (R. t. groenlandicus x pearyi), and boreal (R. t. caribou) caribou ecotypes in the Northwest Territories and Nunavut, Canada. Using a novel approach, we verified that the previously recognized Cape Bathurst, Bluenose-West, Bluenose-East, Bathurst, Beverly, Qamanirjuaq, and Lorillard barren-ground subpopulations were robust and that the Queen Maude Gulf and Wager Bay barren-ground subpopulations were organized as individuals. Dolphin and Union island and boreal caribou formed one and two distinct subpopulation, respectively, and were organized as individuals. Robust subpopulations were structured by strong annual spatial affiliation among females; subpopulations organized as individuals were structured by migratory connectivity, barriers to movement, and/or habitat discontinuity. One barren-ground subpopulation used two calving grounds, and one calving ground was used by two barren-ground subpopulations, indicating that these caribou cannot be reliably assigned to subpopulations solely by calving-ground use. They should be classified by annual spatial affiliation among females. Annual-range size and path lengths varied significantly among ecotypes, including mountain woodland caribou (R. t. caribou), and reflected behavioral differences. An east-west cline in annual-range sizes and path lengths among migratory barren-ground subpopulations likely reflected differences in subpopulation size and habitat conditions and further supported the subpopulation structure identified.