By Alyssa Murdoch, Chrystal Mantyka-Pringle and Sapna Sharma

 Whitefish from a small boreal lake near Inuvik, NT. Credit: Alyssa Murdoch

Canada is often romanticized as one of the last wild frontiers on our planet. With the second-largest land mass of any country, a relatively sparse human population, and stuffed animals sporting maple leaves available at every airport kiosk, how could it not be? And yet, we too are facing a biodiversity crisis that is only being accelerated by climate change.

Far from being a vast untouched wild landscape, Canada’s northern expanses are being relentlessly exploited for resources.  Extensive agriculture, forestry, urban development, and mining have resulted in the disturbance of over 200,000 km² of intact forests since 2000 – an area three times the size of New Brunswick! This loss of intact wilderness has had a direct impact on wildlife that need large wild areas to survive, including now at-risk species such as woodland caribou, wolverine, and lake sturgeon.

Stream degradation due to upstream placer mining (tributary of the Stewart River, YT). Credit: Alyssa Murdoch

Add the effects of climate change to the impact of human activities and you have what could be called a “threat cocktail” – a wicked combination of impacts that often reinforce and amplify each other.  Loss of stream cover due to logging or road building, for example, can accelerate water warming already being driven by hotter average temperatures, with the end result of less oxygen – and lower survival rates -- for fish.

As University and Conservation scientists, we wanted to better understand how these threat cocktails impact aquatic ecosystems, and there is no better place to study this than in northern Alberta. The lower Athabasca watershed in the province is experiencing some of the greatest summer warming on the continent in combination with intense land-use conversion due to oil sands mining. Sensitive fish in this region are therefore contending with habitat degradation at multiple levels --- physical (sedimentation, barriers), chemical (e.g., eutrophication, mining effluent), and thermal (warming waters).

After examining data from over 300 stream catchments in the 250,000 km² region, we discovered that species declines were as much as two times greater in regions where human-driven development occurred in conjunction with climate warming.

The reasons for these declines are likely directly tied to the mix of impacts fish are experiencing in these catchments.  For example, fish that are already being stressed by warming waters may be more vulnerable to added stresses, such as increased sedimentation, lost spawning areas, or navigation barriers (dams or culverts, for example).  Physiological defense and repair mechanisms may be overwhelmed by multiple stressors, leading to poor survival rates for fish.

An Arctic grayling captured in a boreal stream in the Dawson range. Credit: Alyssa Murdoch

But these impacts are not completely straightforward.  Our study also found that some sensitive species, such as trout, living in cooler and less productive higher-elevation watersheds may actually show a modest improvement in numbers when relatively low levels of ecosystem disturbance lead to more nutrients becoming available along with slightly higher water temperatures.  But this uptick may be short lived if disturbance and climate impacts continue to grow, pushing sensitive species too far out of their comfort zone.

In fact, we also saw indications that in many places, sensitive (and high value) species such as trout could be displaced by species that are more tolerant of warmer, murkier waters.  This displacement may ultimately lead to ecosystems with less diversity and, in the long term, potentially less resilience. For sensitive species, being trapped in waters where conditions are becoming increasingly unsuitable can lead to impaired fitness, curtailing growth, reproduction, and ultimately survival.

Unfortunately, our findings do not bode well for a country set to experience both heightened warming and rapidly escalating development pressures in the coming decades.

A challenge for Canadians is reconciling our idealized conception of our land being a vast and unspoiled wilderness with the reality that our country is facing significant – and alarming -- environmental deterioration. To move forward, we need to recognize the shortcomings of our previous approaches and the massive responsibility that we have for protecting what’s left.

There is some hope on the horizon. In a recent poll, more than 60% of Canadians ranked the environment as a critical policy issue. The federal government, in response, has allocated an unprecedented $1.3 billion for conservation – with the aim of protecting 17% of our land and inland waters and 10% of our marine and coastal areas by 2020.  

But as with action on climate change itself, more is needed faster when it comes to addressing the biodiversity crisis. As Canadians, we are stewards of 24% of the world’s remaining intact wilderness, 25% of the world’s wetlands, and 20% of the world’s freshwater resources. These wild areas provide some of the last strongholds for many species that have been decimated elsewhere, such as grizzly bears that have been extirpated from 50% of their historical global range.

Grizzly bear near the Dempster highway. Credit: Dave Kennedy

As well, Canada’s colder, intact regions may provide increasingly critical habitat for the many species expected to shift northwards as the climate warms.  We need to expand our ambition when it comes to protecting wild intact areas and improve our recognition of how new resource projects can lead to cumulative impacts that harm wildlife, particularly in the face of a rapidly changing climate.

The new Impact Assessment Act gives the federal government some tools to address combined impacts, but these will only be useful if the government is willing to apply these "optional" measures, and take the results seriously. Governments also need to move away from piecemeal project planning and start considering impacts at a regional scale. As the saying goes, "the whole is often greater than the sum of its parts."

Historic dredge mining tailings ponds along the Klondike River near Dawson City. Credit: Alyssa Murdoch

If we act now, future generations may still have a chance to experience “wild Canada” firsthand, instead of simply picking up a nostalgic souvenir at a gift shop.

Read the peer-reviewed journal article here.

Alyssa Murdoch is an aquatic biologist and PhD candidate at York University, and a Wildlife Conservation Society Canada Weston Fellow researching the effects of human stressors on northern fish

Chrystal Mantyka-Pringle is a conservation planning biologist with Wildlife Conservation Society Canada and Adjunct Professor, University of Saskatchewan

Sapna Sharma is an Associate Professor, Department of Biology and York University Research Chair in Global Change Biology