Key Findings
Key changes include:
- Rising air temperatures
- More variable surface water levels
- Changing populations of wetland-dependent wildlife
- Concerns regarding contamination of water and fish
- Increased concentrations of ions
Some key changes in the indicators of aquatic ecosystem health have been observed by Indigenous and local communities and detected in data from across the basin. These basin-wide patterns are summarized below. Most of these patterns are evident in both Indigenous knowledge accounts and scientific analyses results, while some are unique to each knowledge system.
Rising air temperatures
Scientific data indicate that air temperatures have increased over the past few decades, especially in winter, which has also been observed by some Indigenous communities in the northern sub-basins. Rising temperatures have led to increased winter stream flows across the basin, the appearance of new fish species in northern rivers, and reduced ice and snow cover in many areas. These changes have impacted the ability for Indigenous communities to access traditional land use areas in winter.
Related signs and signals:
- Temperature, precipitation normals and extremes over time and
- Local observations and oral histories of temperature, precipitation normal and extremes over time
More variable surface water levels
Indigenous knowledge-holders across the basin have observed that water levels in many rivers, lakes and deltas are more variable than in the past. Fluctuating high and low water levels pose challenges in reaching traditional harvesting areas by boat and are often associated with increased observations of sand bars and navigable hazards. Scientific evidence similarly indicates that climate change, in combination with river regulation, has resulted in various degrees of reduced water levels, primarily in the three major deltas of the basin, the Peace-Athabasca, Slave and Mackenzie River Deltas.
Related signs and signals:
- Local observations and oral histories of changing flow, water levels in rivers and lakes over time and
- Seasonal statistics including changes in flow, water levels in rivers and lakes over time
Changing populations of wetland-dependent wildlife
Reduced populations of wildlife such as muskrat (Ondatra zibethicus) and fish have been observed by Indigenous communities in most sub-basins, leading to a decline in the consumption of these and other country foods. A basin-wide trend in declining populations, especially in popular sport fish in accessible surface waters, has been documented in fish stock information as well.
Related signs and signals:
- Oral histories of aquatic furbearing species, including abundance, health and distribution;
- Local observations about changes in timing of local fishing activity and yield;
- Oral histories and local observations of fish abundance, timing and distribution, species diversity and fish health condition; and
- Fish (including salmon, suckers (Catastomus spp.), pickerel (Sander vitreus), burbot (Lota lota)) abundance, timing and distribution, species diversity and fish health condition.
Concerns regarding contamination of water and fish
Indigenous communities across the basin share concerns about the potential contamination of water and fish from local and upstream industrial development, and many communities have observed a decline in water quality and the health of fish. Scientific data generally do not show widespread impacts on water quality or on fish health, as indicated by the absence of trends from 2000 to 2018 in water quality parameters that have guidelines, and only locally detected fish tissue contamination in some fish species in parts of the basin. Exceptions to these general trends were found in specific areas: downstream of wastewater discharges and near mining sites, in the Athabasca River and its tributaries in the Lower Athabasca Oil Sands Region and in watersheds developed for agriculture.
Related signs and signals:
- Local observations and oral histories of good water, poor water, seasonal differences, land-based consumption practices;
- Oral histories and local observations of fish abundance, timing and distribution, species diversity and fish health condition;
- Ambient surface and ground water concentrations; and
- Fish (including salmon, suckers, pickerel, burbot) abundance, timing and distribution, species diversity and fish health condition.
Increased concentrations of ions in surface water
An increase in ions (which are mainly dissolved salts) were measured in surface waters across the basin, but these changes did not result in exceedances of guidelines for aquatic life. Increased groundwater contribution to subarctic watersheds related to permafrost thaw has been hypothesized as a driving factor in the Peel, Liard and Mackenzie Great Bear sub-basins. In other areas of the basin it may be related to reduced water levels, due to climate change.
Related signs and signals:
- Ambient surface water concentrations.
Important Connections
The signs and signals assessed in the SOAER do not stand in isolation. Rather, together they represent an overall status of aquatic ecosystem health.
Everything is connected. The signs and signals assessed in the SOAER do not stand in isolation. Rather, together they represent an overall status of aquatic ecosystem health. This means that signs and signals are connected – the change in one will affect others. For example, changes in water quantity may affect water quality, fish health and population. In addition, fish populations may be directly impacted by loss of habitat. The most important connections between signs and signals identified in the SOAER are summarized below.
Climate change is a widespread stressor on aquatic ecosystem heath across the basin. Increased air temperatures and, to a lesser degree, changes in precipitation patterns, have changed ice and flow patterns in rivers, changed snow cover in many areas, reduced water levels, impacted water quality in various ways across the basin, and impacted fish populations and fish health. The quality of habitat, such as wetlands in deltas and distribution of fish species, has been altered. Climate change has also affected access to traditional land use areas, in particular in winter in the northern part of the basin, and thus has impacted the health and wellbeing of Indigenous communities.
Land use has impacted aquatic ecosystem health in the basin in many ways, in particular, there are significant land use pressures in the Peace and Athabasca sub-basins. The human footprint from land uses for agriculture, industrial development and public roads, along with climate change and fishing pressure, has resulted in reduced water quality, reduced habitat quality and availability, and reduced populations of fish species, some to extirpation. These impacts have resulted in reduced confidence and access to traditional land use areas and country foods in these sub-basins.
Fishing pressure has likely been a factor in many of the historical fish population declines across the basin, including lake and river populations of sport fish in the Peace and Athabasca sub-basins and in Great Bear and Great Slave Lakes.
Recent and Emerging Patterns
The most significant emerging trend since the publication of the 2003 SOAER is the more widespread and stronger evidence of climate change impacts
The most significant emerging trend since the publication of the 2003 SOAER is the more widespread and stronger evidence of climate change impacts. Examples are the basin-wide increase in winter flows, expanding lakes in the Great Slave sub-basin, the appearance of new fish species in subarctic regions, and the significant consequences of permafrost thaw on the landscape through erosion and impacts on water quantity and quality in the northern sub-basins. These changes warrant more research and monitoring to better understand their impacts on the integrity of the aquatic ecosystem and populations of native species. Observations by Indigenous and local communities can direct scientific research and monitoring; for example, the observed changes in taste and odour of water and fish may be early warning signs of climate impacts on water quality and fish health.
Some recent trends in aquatic ecosystem signs and signals show a recovery owing to management intervention. For example, phosphorus concentrations in rivers downstream of wastewater discharges have stabilized or declined due to improved wastewater treatment technology. Some fish populations are recovering in response to fishery management strategies.
This report shows that much of the information gathered from Indigenous knowledge and scientific sources is complementary and paints a clear picture of the status of aquatic ecosystem health and the key pressures upon it. Informed by Indigenous and scientific understanding, some parts of the assessment result in different pictures of the status of aquatic ecosystem health and pressures, for example, the degree of concern over contamination of water and country foods. This may indicate an inherent difference in perspective and the way the knowledge is derived in each knowledge system. It may also indicate a degree of uncertainty over the multitude of potential ways land development and water and air emissions can influence downstream water and fish quality and their consumers. Much work using both Indigenous knowledge and science remains to be done to better characterize, track, and communicate local, regional and basin-wide human health risks associated with the consumption of water and country foods from the MRB.