by Alana Coulombe, Education programs administrator

Canada’s freshwater is under threat against the impacts of climate change, in addition to shoreland development and traditional land use practices. Increasing climate change pressures and associated hydrologic changes will alter where, when, and how precipitation falls and water flows. This, in turn, will impact the quantity, quality, and availability of Canada’s freshwater resources. The cumulative effect of these multiple stressors, along with a rapidly changing climate, is expected to further disrupt freshwater ecosystems, including their ecological processes, ecosystem services, and biodiversity.

The main climate change impacts affecting Canada’s freshwater include changes in temperature, precipitation patterns, wind speeds, and the frequency and intensity of extreme events like heavy storms, floods, and droughts (Rose et al., 2023). A freshwater ecosystem’s response to climate change varies depending on the magnitude of impact, interactions with other stress factors, and the individual ecosystem’s characteristics.

Intensifying human activities can result in habitat degradation and fragmentation, altered flow regimes, water pollution, overexploitation of natural resources, and the introduction of invasive species (Coleman et al., 2022). Shoreland development for recreational, residential, industrial, or agricultural purposes can have devastating impacts on the shoreline and surrounding aquatic and terrestrial ecosystems. Traditional land use practices, including engineered shorelines around industrial sites, removal of native vegetation on the land and in the water, fertilizer and pesticide application on agricultural fields, and hardened infrastructure for urbanization, also contribute to deteriorating shorelands and freshwater quality.

Lake, river, stream, and wetland ecosystems are simultaneously affected by climate change and other human-induced stresses such as urban expansion (Rose et al., 2023). These interactions accelerate the loss of biodiversity and impair ecosystem services, threatening the functional capacity of freshwater ecosystems (Coleman et al., 2022). Since freshwater ecosystems are hydrologically and ecologically connected with one another and their surrounding landscapes, changes are integrated throughout their watersheds (Rose et al., 2023). As responsible freshwater stewards, we need to understand the combined impacts of urbanization and climate change in order to identify means of effective mitigation. Restoring natural ecological processes to effectively treat the causes of degradation, rather than the symptoms, will promote long-term watershed conservation and protection.

Landscape connectivity is essential for maintaining biodiversity and ecological functioning across a watershed, including organism dispersal, water flow, and solute movement (Johnson et al., 2010). Spatial interactions between aquatic ecosystems and surrounding landscapes affect their resistance and resilience to change (Johnson et al., 2010). For example, restoring natural shorelines creates diverse habitats, improves habitat connectivity, and maintains healthy ecosystems that support native wildlife and macroinvertebrate communities. Simply leaving overhanging branches, leaves, fallen trees, woody debris, and aquatic vegetation along your shoreline provides critical habitat features like shelter, shade, food, and transition zones for aquatic and terrestrial species.

With increasing fragmentation, natural connections in the landscape are severed due to hydrological and geomorphological modifications (Johnson et al., 2010). Ecosystem indicators combine multiple attributes, including species biodiversity, to provide an integrative assessment of ecological status and integrity that reflects the compound impacts of climate change and land development (Rose et al., 2023). For improved resiliency, both the ecological functioning and biodiversity of freshwater ecosystems must be restored to their natural connective state.

Climate change exerts additional pressures on freshwater ecosystems both directly and indirectly through interactions with other factors like hydromorphological changes (Johnson et al., 2010). Climate variations, such as the amount and type of precipitation, directly affect the hydrologic characteristics that define the spatial depth, extent, and flow of freshwater ecosystems (Rose et al., 2023). Hydrologic indicators, such as water level, wetland extent, and streamflow, influence freshwater ecosystems and can be used to monitor the combined impacts of climate change and land conversions. For example, lake level variations are linked with broad-scale spatial patterns in precipitation, evaporation, stormwater runoff, and water use and thereby integrate responses to climate-related impacts and other input and outflow sources (Rose et al., 2023).

Urban expansion and climate-related impacts can also destroy wetland areas, impairing natural ecosystem services such as flood protection, water quality regulation, lake and river connectivity, carbon sequestration, and wildlife habitat. Moreover, water quality indicators, such as temperature, clarity, nutrient content, salinity, and dissolved organic carbon and oxygen, can monitor the physical, chemical, and biological characteristics of water relevant to human use and climate impacts.

Enhancing a shoreline’s natural features and capacity to adapt in response to changing environmental conditions will improve its long-term stability and resiliency. Restoration projects serve to mitigate the risks of degradation and restore the dynamic nature of natural shorelands to foster a natural line of defence against climate-related impacts. For example, accumulating woody debris and growth of native aquatic vegetation along shorelines increases habitat complexity, attenuates wave energy to reduce the risk of erosion, and improves stream hydromorphology (Johnson et al., 2010). Conservation efforts thus require a combination of management actions including riparian revegetation, stormwater management, and maintaining adequate stream flow regimes (Coleman et al., 2022).

Creating a natural shoreline buffer with native species of grasses, trees, shrubs, and wildflowers will contribute to the health and beauty of Canada’s freshwater. Numerous studies demonstrate the importance of native riparian vegetation, highlighting its role in stream bank stabilization, water quality protection, temperature moderation, and woody debris and organic matter input (Coleman et al., 2022). Naturalizing your shoreline fosters proactive steps to reduce shoreline erosion and mitigate flood impacts. Deep-rooted vegetation, like trees and shrubs, promote long-term shoreline stabilization and climate change resilience by binding the soil and acting as natural barriers to reduce surface runoff, slow rising floodwaters, and filter pollutants and excess nutrients. Explore The Natural Edge’s Native Plant Database to discover vegetation naturally suited to withstand the climate, soil types, and environmental conditions of your local area, and be sure to check if The Natural Edge can deliver a shoreline restoration project in your area.

With increasing shoreland developments and climate change pressures, a shift to nature-based solutions will promote greater shoreline stability, habitat enhancement, and improved freshwater health and biodiversity. Native riparian vegetation and natural wood input will support natural channel dynamics, thereby building capacity for shoreland resiliency in freshwater ecosystems (Johnson et al., 2010). Our actions to protect freshwater ecosystems from the combined impacts of climate change and other human-induced stresses will ultimately shape the future of Canada’s freshwater resources.

References
Coleman, R. A., Chee, Y. E., Bond, N. R., Weeks, A., Griffiths, J., Serena, M., Williams, G. A., & Walsh, C. J. (2022). Understanding and managing the interactive impacts of growth in urban land use and climate change on freshwater biota. Global Change Biology, 28(4), 1287–1300. https://doi.org/10.1111/gcb.16015
Johnson, R. K., Battarbee, R. W., Bennion, H., Hering, D., Soons, M. B., & Verhoeven, J. T. A. (2010). Climate change: Defining reference conditions and restoring freshwater ecosystems. In M. Kernan & R. W. Battarbee & B. Moss (Eds.), Climate change impacts on freshwater ecosystems (pp. 203-235). Wiley-Blackwell. https://doi.org/10.1002/9781444327397.ch9
Rose, K. C., Bierwagen, B., Bridgham, S. D., Carlisle, D. M., Hawkins, C. P., LeRoy Poff, N., Read, J. S., Rohr, J. R., Saros, J. E., & Williamson, C. E. (2023). Indicators of the effects of climate change on freshwater ecosystems. Climatic Change, 176(23). https://doi.org/10.1007/s10584-022-03457-1

 

This blog is part of a climate change toolkit that is generously funded by The Catherine and Maxwell Meighen Foundation. View the full toolkit on our website.