Impacts of oil exploration
The oilsands of northeast Alberta has abundant oil reserves, but its heavy black viscous oil, termed bitumen, is expensive to extract and must be rigorously treated to convert it into an upgraded crude oil. Current oil prices per barrel have recently made it cost-effective for companies to extract and process the bitumen. SAGD (steam assisted gravity drainage) is a common method used to extract this oil. Seismic and delineation drilling determine where and how much oil is present. Steam is then used to heat and move the material through underground veins to an extraction area. These operations must occur in the winter, when the ground is frozen and are strictly controlled by the Alberta government due to the sensitive nature of boreal forest.
We have been working in collaboration with the Chipewyan Prairie Dene First Nation, Statoil Canada and the Alberta provincial government to monitor impacts of the oil exploration on the caribou, moose and wolf living on oil sands lease areas in northeast Alberta.
The caribou, moose and wolf are monitored because their large size and ranging behavior make them likely to be impacted by oil development activities. The caribou is a species of particular concern because some investigators claim it will be extinct in the oil sands within the next two decades. The moose offers a good comparison species because it is similar in size but differs in microhabitat and social structure. The moose is a primary prey species of the Chippewa Prarie Dene First Nation. The caribou is a prey species of secondary importance to the Dene. The wolf is the primary non-human predator of the moose and caribou.
The Alberta government is proposing to kill up to 80% of the wolves in the oil sands to slow the rate of caribou decline. They argue that climate change and habitat disturbance are causing deer, the preferred prey of wolves, to move north into the oil sands. Wolves are said to increase in response, increasing the risk of predation on caribou. Our work suggests that there may be better options.
We used Conservation Canines detection dogs to comprehensively sample the study area for caribou, moose and wolf scat each year, beginning when the oil crews first arrive on site in December up until they pack up and leave in late March.
The comprehensive sampling provided by the dog teams allowed us to simultaneously determine:
- How population size changes for each species across years
- What factors in the environment each species is attracted to, or avoiding
- How do the stress, nutritional status and reproduction of each species vary over space—relative to distance from key resources and anthropogenic disturbances – and
- Time—relative to intensity of extraction activities within and between years
The monitoring occurred between January and March of 2006, 2007 and 2009. The 2,500 km2 study area is divided into 46 contiguous 8 km x 8 km cells. Detection dogs were specially trained to detect scat from the study species in deep snow, over large remote areas. The dog teams sampled each cell four times, at the start, through the peak and end of oil exploration activities each field season. We determine the abundance and distribution of the moose, caribou and wolf through DNA-based mark-recapture analyses, using DNA extracted from fecal samples of these three species. We measure spatial changes in resource selection patterns and physiological health, all in relation to distance from natural and anthropogenic features, food availability and temporal patterns in extraction activities.
The Center returned with six teams in 2013. The about 2000 samples from moose, caribou and wolves were collected over the course of three months. The data is currently being analyzed.
Our physiological health measures partition the various pressures impacting these species as follows:
- Cortisol: Cortisol is an adrenal hormone secreted in response to many external stressors. Elevated cortisol metabolites in feces indicate stress impacts, such as those resulting from noise and other direct disturbances resulting from the rapid influx of human activities, as well as from reduced nutrition.
- Thyroid hormone concentration: Animals reduce thyroid hormones under nutritional stress to reduce metabolism, making their body more efficient at storing energy. Low thyroid hormone levels thus reflect nutritional stress, implying reduced food availability. (Cortisol also tends to be elevated under nutritional stress, as cortisol releases internal stores of glucose for increased energy.)
- Reproductive hormones in caribou: The majority of females are pregnant during winter. Progesterone indexes the occurrence and health of their pregnancies.
Strong impacts of human activity were indicated by changes in resource selection and in stress and nutrition hormone levels as human-use measures were added to base resource selection models (including ecological variables, provincial highways, and pre-existing linear features with no human activity) for caribou.
Wolf predation and resource selection so heavily targeted deer (Odocoileus virginiana or O hemionus) that wolves appeared drawn away from prime caribou habitat. None of the three examined species showed a significant population change over four years.
However, caribou population estimates were more than double those of previous approximations for this area. Our findings suggested that modifying landscape-level human-use patterns may be more effective at managing this ecosystem than intentional removal of wolves (Wasser et al 2011).
To further address these issues, we sent caribou fecal samples collected in 2009 to Washington State University for diet analyses. We found that 60% of the caribou winter diet consisted of lichen, which is extremely high in polysaccharides. This food source is particularly vital to pregnant caribou as it is high in glucose, which is the primary food source to the fetus. Fecal cortisol levels were strongly negatively correlated and thyroid hormone strongly positively correlated with the percent of lichen in that same fecal sample. Moreover, both elevated cortisol and diminished thyroid hormone resulted in suppression of progesterone in female caribou, compromising their pregnancies.
Since areas of high use human activities tend to be concentrated in lichen rich areas, our results suggest that moving activity centers away from lichen rich areas may be the best strategy for mitigating caribou declines in the oil sands.
Moreover, owing to the preference of wolves for deer, removing wolves from the population to protect caribou could actually place the ecosystem at markedly greater risk by accelerating the expansion of deer into this ecosystem.
Wasser, SK, JL Keim, ML Taper, SR Lele. 2011. The influences of wolf predation, habitat loss, and human activity on caribou and moose in the Alberta oil sands. Frontiers in Ecology and the Environment.