Synthesis of freshwater science in Canada

An overview of key findings as a foundation to inform prioritization of collaborative freshwater science activities

Executive summary

The landscape of freshwater science in Canada is vast and complex with a wealth of academic, government, non-government, Indigenous, and community-based scientific water-related expertise. To understand and synthesize the current state of freshwater science in Canada, a team of over 100 subject matter experts from ECCC, AAFC, NRCan, and DFO investigated 25 key freshwater priorities, challenges, and issues facing aquatic ecosystems in Canada, principally focused on the current understanding of water quality and aquatic ecosystem health. This document, a Synthesis of Freshwater Science in Canada, is an overview of that investigation highlighting key messages and science needs moving forward.

The freshwater priorities, challenges, and issues that are found in this Synthesis were categorized under five national themes, namely, Indigenous co-development and the delivery of science programs and strategies, climate change and climate variability, land-use and water-use changes, contaminants and pollution, and cross-cutting challenges.

While this Synthesis is not intended to be a definitive collection of every freshwater issue facing our country, it may be viewed as an opportunity to advance new questions, challenges, and opportunities to inform the discussion of integrated freshwater science, responsibility, stewardship, management, and action with key partners inside and outside of the federal government.

Seizing the opportunity

As a next step, this Synthesis provides a launching point for the development of a National Freshwater Science Agenda.

There are five foundational elements that have been repeatedly raised as key outcomes to actions from the Synthesis of Freshwater Science in Canada:

1. National science coordination to guide multidisciplinary and interdisciplinary collaboration on pan-Canadian priorities and needs.
2. User-driven freshwater science to support distinctive watershed, regional and local priorities within a national frame.
3. User-centric knowledge mobilization as an integrating mechanism of tools and experts to better connect, translate, and reflect the needs of freshwater science-users in Canada.
4. Digital tools, critical and innovative infrastructure, and standards to enhance freshwater science as well as operationalize the connectivity and mobilization of freshwater knowledge.
5. Bridging, braiding, and weaving of Indigenous science and knowledge to respectively represent the distinct and diverse Indigenous perspectives and knowledge systems.

This next step to develop such a Science Agenda would be a means to focus inclusive, collaborative, and coordinated freshwater science to inform management, and investment decisions. It can prioritize, align, and enhance coordination of freshwater science in Canada and be a roadmap for investors, doers, and consumers of freshwater science in Canada. Ultimately, this Science Agenda would advance freshwater science in Canada starting with the most pressing needs or challenges to achieve national and regional sustainable freshwater stewardship goals.

Introduction

The landscape of freshwater science in Canada is vast and complex with a wealth of academic, government, non-government, Indigenous, and community-based scientific water-related expertise. Many federal departments and agencies carry out freshwater science, including Environment and Climate Change Canada (ECCC), Fisheries and Oceans Canada (DFO), Natural Resources Canada (NRCan), Agriculture and Agri-Food Canada (AAFC), Health Canada, Parks Canada, and the National Research Council, all of whom provide science leadership on federal responsibilities and national obligations. Furthermore, water research funding under the granting councils, Research Chairs, and Excellence programs has developed a significant network of water experts in academia. Beyond academia, there are a growing number of programs at local to regional levels supporting freshwater stewardship such as the Indigenous Guardian Programs, community-based monitoring programs, and inclusive citizen science activities. Collaborative efforts through these programs have strengthened an already significant network of water science and knowledge proficiency.

In an effort to understand and synthesize the current state of freshwater science in Canada, a team of over 100 subject matter experts from ECCC, AAFC, NRCan, and DFO investigated 25 key freshwater priorities, challenges, and issues facing aquatic ecosystems in Canada, principally focused on the current understanding of water quality and aquatic ecosystem health. This document, a Synthesis of Freshwater Science in Canada, is an overview of that investigation highlighting key messages and science needs moving forward.

This Synthesis has many potential beneficiaries. It will serve as a foundation to inform prioritization of freshwater science needs or issues in Canada. It also provides scientific support to advancing the Government of Canada’s freshwater commitments. A Freshwater Science Workshop was held in February 2021 to solidify the efforts in creating this Synthesis and discuss considerations for next steps.

Investigations on these freshwater topics drew heavily on the complementary disciplines and perspectives under ECCC, AAFC, NRCan, and DFO. It is a testament to the breadth of subject matter proficiency that Canada has established in the aquatic sciences—tackling challenges such as water balance, harmful algal blooms, invasive species, and the protection of ecosystem services and aquatic biodiversity, all in a changing climate. Although the priorities and science gaps will continue to evolve beyond the topics synthesized here, the scientific understanding of these and other freshwater-related issues is established, focused, and highly collaborative.

This Synthesis presents key messages, summaries, and key gaps and needs on this collection of 25 freshwater priorities from both national and regional perspectives, beginning with a reflection on opportunities for Indigenous co-development of science programs and respectful braiding of knowledge systems. Icons representing each topic investigated here are used throughout to quickly capture and emphasize the linkages between topics, reflecting the web of interconnectedness of freshwater-related issues to the Canadian environment between the coasts. It concludes with foundational needs reflected in these topics as well as opportunities for next steps.

Indigenous co-development and the delivery of science programs and strategies

Key messages

Water is life. Indigenous Peoples have a deep spiritual relationship to water. Acknowledging this relationship will greatly facilitate collaborative work to keep water safe, clean and well managed.

Indigenous Science is a valuable, stand-alone, time-tested way of knowing and understanding the environment that has been used since time immemorial to protect species and the environment (e.g., sea ice mapping and critical habitat for species at risk among others).

The equal and respectful co-development of research, particularly for water initiatives on overarching environmental challenges such as climate change, the Arctic, or cumulative effects requires a more holistic and ethical approach. Long-term initiatives with Indigenous partners, could serve as a mechanism for innovation and meaningful relationship-building in support of reconciliation.

Context

Indigenous Peoples have an unbreakable and sacred connection with the land and water that extends back since time immemorial. Water is the giver of life (Nibi onje biimaadiiziiwin in Anishinaabe water law). A wide range of traditional activities depend on water for transportation, drinking, sustenance, cleaning, spiritual purification, and other cultural activities. Access to good water also provides essential habitat for plants and wildlife, such as fish and caribou that are integral parts of Indigenous culture, food, medicine, and economy. Without clean water all life will perish. Clean water is recognized as a basic human right, as water is indispensable to healthy livelihoods and fundamental in maintaining the dignity of all human beings (UN, 2019). International human rights law obliges states to work towards universal access to water for all, without discrimination, while prioritizing those most in need (Goal #6 of the Water and Sanitation – United Nations Sustainable Development). Article 25 of the United Nations Declaration on the Rights of Indigenous Peoples (PDF; 150kB) entrenches Indigenous rights to maintain and strengthen their distinctive spiritual relationship with water (see Craft, 2019).

Science has never been uniquely western—rather a more equitable framework is needed where all knowledge systems can coexist (Turnbull, 1997). Indigenous science and western approaches to understanding and protecting water as a holistic resource have much in common.Western science acquires knowledge through observations and measurements. The scientific method is the foundation of western science’s ability to provide context, analysis and insight. Indigenous science also acquires knowledge through observations and measurement. These observations are passed down, in many cases, through an oral knowledge sharing tradition as well as song, language, law and ceremony among others. A dynamic knowledge system, Indigenous science is constantly evolving through intergenerational experience. Indigenous science is relational, and as such is woven into, and inseparable from, other aspects of Indigenous Knowledge systems, such as legal, spiritual and cultural knowledge. The relationships between Indigenous Peoples, the land, organisms in the ecosystem and surrounding habitats are the pillars on which Indigenous science provides context, interpretation and deep insight. In both approaches, the truth emerges over time from the sharing and collective interpretation of findings.

The strengths of these different approaches are highly complementary, and thus braiding these knowledge systems can yield greater understanding. Indigenous science has a long-term vision that is highly integrative and deeply understands that humans are a part of, and must remain in balance with, ecosystems (Indigenous Circle of Experts, 2018). Indigenous land stewardship practices are also inherently systems-oriented and holistic in scope. Indigenous Peoples are also well-positioned to be guardians and water stewards of ecologically sensitive landscapes, especially ones involving their traditional lands.

By contrast, western science has a depth of knowledge about components of ecosystems, albeit typically over much shorter time periods. Geology and paleoecology being interesting examples of studies that may be particularly well suited to braiding knowledge as both approaches embrace local to regional spatial scales over decades to millenniums. An approach that integrates both Indigenous and western science points of view, also called Etuaptmumk or “two-eyed seeing,” a Mi’kmaq approach, has real potential to improve science and policy outcomes for all Canadians (e.g., Bartlett et al., 2012, Reid et al., 2020). Indigenous Knowledge and innovation in collaboration with western science practices is particularly well suited to addressing the challenges of climate change, biodiversity loss and ecological risk assessment in support of protecting Canada’s freshwater resources (e.g., What Conservation can learn from Indigenous Communities).

Ongoing Federal Programs and Initiatives

Audits of Indigenous programs conducted by other departments highlight there are seven pillars of successful programming. For instance, a review of Fisheries and Oceans Canada (DFO)’s Indigenous programs by the National Indigenous Fisheries Institute highlights problems with five long-standing programs: including, the need for simpler, multi-year agreements; straight-forward reporting requirements; flexible approaches to capacity building, and the ongoing need for open dialogue with Indigenous partners to better address concerns as they arise. Audits of NRCan’s programs have further highlighted the need for good communication and the need to seize opportunities to reinforce relationships between programming and Indigenous rights holders (e.g., the 2019 Audit of the Canada Lands Survey Program).

Some audits report that no Indigenous governments or organizations were successfully ‘interviewed’ at any stage of the program. For programs that are intended to support Indigenous communities, this lack of engagement is a key gap that highlights an important systemic issue—that Government of Canada programs are not addressing the needs of those they are intended to serve. From a community perspective, there is also a lack of enthusiasm to participate in mechanisms and programs that don’t reflect the needs and perspectives of the partnering community. These are hurdles that could be overcome through respectful relationship building with Indigenous partners. In the absence of shared, mutually beneficial dialogue, programs will continue to ‘fail to develop comprehensive understanding of and continued engagement with rights holders’ (e.g., see the 2020 Joint Audit and Evaluation Report).

Some examples of existing flexible programs that support co-developed research with communities and respectful practices are as follows:

• Inuit Field Training Program (PDF; 731 kB) and the Inuit Learning and Development Program
• Guardian Pilot Program (ECCC, CIRNA, DFO, PCA, NRCan, and IAAC)
• Environmental Geoscience Program (NRCan,and Polar Knowledge Canada)
• Setting New Directions (CIHR, NSERC, and SSHRC)
• Te Mana o te Wai (Māori-led, Māori-owned freshwater, New Zealand)

Knowledge and program needs

There is an urgent need for more flexible programming, research co-developed with communities, and transformative training to promote respectful engagement practices that better address and understand the current and emerging needs of Inuit, Métis, and First Nations communities.

The following list offers key needs, intended as a starting point towards meaningful dialogue.

Key gaps and needs

There is a power imbalance when Government of Canada employees work with Indigenous communities. Awareness of this imbalance and the historical context of these sensitive issues is needed such as through training for managers and scientists to better understand the unique perspectives and needs of Indigenous Peoples.

Canada has adopted the United Nations Declaration on the Rights of Indigenous Peoples and officials need to familiarize themselves with the rights and obligations articulated in the Declaration to incorporate these responsibilities into their work.

Meaningful relationship-building will require long-term investment, flexibility and a willingness to do business differently. Pivoting towards a more open, ongoing and meaningful relationship with Indigenous Peoples requires acknowledgement of Indigenous rights, data sovereignty and supports for community-driven goals.

Truth and reconciliation:

There is a power imbalance when Government of Canada employees work with Indigenous communities. Awareness of this imbalance and the historical context of these sensitive issues is imperative for meaningful engagement with First Nations, Inuit and Métis governments and communities (The National Centre for Truth and Reconciliation website).

Indigenous governments and communities should be approached with the same care and consideration as with any other international relationship.

To build successful relationships, managers and scientists require training to better understand the unique perspectives and needs of Indigenous rights holders. For forward-facing employees this training should be mandatory (Truth and Reconciliation Commission Call #57).

Staff collaborating with Indigenous partners need to be multicultural, multidisciplinary, and multilingual as language is deeply embedded in the understanding and interpretation of Indigenous Knowledge systems. Translation and interpretation services must be supported to allow for knowledge sharing.

Data sovereignty and access to information:

Federal departments and institutions are legally obliged to respect Indigenous Peoples’ inherent and constitutional rights to self-determination and self-government, including rights to data sovereignty.

Federal scientists should consult with Indigenous Nations and governing bodies when considering the release of Indigenous data, information and scientific outputs that rely on such data and information.

Free, prior, and informed consent should be sought concerning the collection, use and dissemination of data (Food and Agriculture Organization, 2016 (PDF; 901 kB)). It is linked to the right to self-determination and is backed by the United Nations Declaration on the Rights of Indigenous Peoples (PDF; 166 kB) among numerous other international instruments.

All policies and agreements with Indigenous Peoples, communities, and governments should adhere to Ownership, Control, Access, and Possession (®) standards—the approved framework to support self-determination of research, information, and data gathering when working with Indigenous communities. Note, new policies such as the tri-agency policy statement on ethical conduct of research with Indigenous Peoples do not meet OCAP standards.

Develop guidelines in natural science journals on how to appropriately publish Indigenous Knowledge or information on cultural resources (Wong et al., 2020).

Traditional Knowledge is peer-reviewed. It has been vetted by Knowledge Keepers over generations.

Understanding water rights and allocation:

Indigenous water rights must be recognized, protected, and upheld as affirmed in treaties and other agreements.

Indigenous Peoples have the right to redress for resources which they have traditionally owned or otherwise occupied or used, and which have been used or damaged without their free, prior and informed consent (UNDRIP).

Fundamental rights to self-determination of Indigenous Peoples to freely determine their political status and freely pursue their economic, social, and cultural development must be respected (e.g., Charter of the United Nations, International Covenant on Economic, Social and Cultural Rights, International Covenant on Civil and Political Rights, and the Vienna Declaration and Programme of Action).

Co-developed research and relationship building:

Expert advice provided to Indigenous communities and governments should be culturally appropriate, collaborative, and ethical.

Partnering communities should be involved from the very beginning of the co-developed research process (e.g., during project design and application for funding).

Initiatives should pivot towards increasing capacity amongst Indigenous Nations and communities.

Criteria for measuring ecosystem health should not be solely drawn from non-Indigenous sources.

Duty to accommodate, consult, and act in good faith should be always applied.

Decision-making and data stewardship should remain at the community-level.

Data collection, indicator selection, and interpretation of data collected, wherever of interest to the community, should be Indigenous led. Community-based monitoring should be Indigenous controlled if the local community is interested in doing so.

Financial support for training of community members towards Indigenous aspirations in STEM fields should be routinely offered (e.g., see Environmental workforce training programs for Indigenous communities – BEAHR).

Actionable tools that directly inform decisions and policies are urgently required. Creating these tools takes innovators, boundary spanners, and reciprocal, long-term partnerships (Westwood et al., 2020).

Using Indigenous place names is an inherent act of recognition of the history of Indigenous Peoples’ relationship with the land and water.

Facilitating long-term partnerships is a means to foster cross-cultural awareness and respect, and to foster these qualities in the next generation of Indigenous and non-Indigenous researchers alike.

Take home message

Water is our most precious resource, yet freshwater is less than 3% of the global water supply. Clean water is essential for life. Unfortunately, freshwater impairment is widespread and is particularly degraded in many rural and Indigenous communities that continue to have “boil-water” or “do-not-consume” advisories. Climate change is expected to exacerbate these challenges, resulting in the further degradation of freshwater resources, which will continue to pose a significant threat to the health of all Canadians and particularly to Indigenous Peoples.

Acknowledgements

The original concept for this piece was developed at the Indigenous Support and Awareness workshops in the summer of 2020 hosted by the inter-departmental Indigenous STEM cluster. Many thanks to the Elders, presenters, attendees, and organizers of this workshop series for their thoughtful insights and feedback. We also respectfully acknowledge that much of this text was written on the unceded, unsurrendered, traditional Wəlastəkw territory in central New Brunswick.

References

Bartlett, C., Marshall, M., and Marshall, A. 2012. Two-Eyed Seeing and other lessons learned within a co-learning journey of bringing together indigenous and mainstream knowledges and ways of knowing. Journal of Environmental Studies and Sciences, 2, pp. 331-340.

Henri, D.A., Brunet, N.D., Dort, H.E., Odame, H.H., Shirley, J., and Gilchrist, H.G. 2020. What is effective research communication? Towards cooperative inquiry with Nunavut communities. Arctic, 73(1), pp. 81-98.

Horowitz, L.S., Keeling, A., Lévesque, F., Rodon, T., Schott, S., and Thériault, S. 2018. Indigenous Peoples’ relationships to large-scale mining in post/colonial contexts: Toward multidisciplinary comparative perspectives. The Extractive Industries and Society, 5(3), pp. 404-414.

Indigenous Circle of Experts. 2018. We Rise Together: Achieving Pathway to Canada Target 1 through the creation of Indigenous Protected and Conserved Areas in the spirit and practice and reconciliation (PDF 4.98 MB);. Report and Recommendations. Accessed 7 August 2020.

Reid, A.J., Eckert, L.E., Lane, J.-F., Young, N., Hinch, S.G., Darimont, C.T., Cooke, S.J., Ban, N.C., and Marshall, A. 2020. “Two-Eyed Seeing”: an Indigenous framework to transform fisheries research and management. Fish and Fisheries, 22(2) pp. 243-261.

Turnbull, D. 1997. Reframing science and other local knowledge traditions. Futures, 29(6), pp. 551-562.

Westwood, A.R., Barker, N.K., Grant, S., Amos, A., Camfield, A.F., Cooper, K., Dénes, F.V., Jean-Gagnon, F., McBlane, L., Schmiegelow, F.K.A., Simpson, J.I., Slattery, S.M., Sleep, D.J.H., Sliwa, S., Wells, J.V., and Whitaker, D.M. 2020. Toward actionable, coproduced research on boreal birds focused on building respectful partnerships. Avian Conservation and Ecology, 15(1), p. 26.

Wong, P.B., Dyck, M.G., Arviat Hunters and Trappers, Ikajutit Hunters and Trappers, Maykalik Hunters and Trappers, and Murphy, R.W. 2017. Inuit perspectives of polar bear research: lessons for community-based collaborations. Polar Record, 53(270), pp. 257-270.

Climate change and climate variability

Hydro-climatic extremes (floods and droughts)

Summary

Ongoing and projected future changes to Canada’s freshwater resources and aquatic ecosystems are significantly impacted by the occurrence of hydro-climatic extremes; namely floods and droughts, which act on a variety of temporal and spatial scales. Freshwater floods mainly result from excess precipitation, snowmelt, ice jams, rain-on-snow, or a combination of these factors. While future warming is expected to affect these flood-causing factors, it is not straightforward how these changes will interact to affect the frequency and magnitude of future floods. Canada is projected to warm in all seasons under a range of emission scenarios, thereby increasing drought risk in many regions of the country. How much summer droughts will increase in frequency and intensity depends on whether future summer precipitation will offset increased evaporation and transpiration. Smaller snowpacks and earlier snow and ice melt associated with warming temperatures could increase drought risk in the many snowmelt-fed basins across Canada that rely on this water source, as well as in regions that depend on glacial meltwater for their main dry-season water supply. A changing climate will therefore impact several factors that influence flooding and drought events, but given the complexity of these events, short-term predictions and long-term projections remain uncertain. Enhanced integration among federal, provincial, territorial, Indigenous, municipal, and university programs/researchers is required to determine the environmental, social, economic, and cultural impacts of future hydro-climatic extremes and resultant freshwater availability.

Key gaps and needs

Integrate global and regional climate, hydrologic, and water quality models. Enhanced research to improve integration of global/regional climate and weather models with distributed surface and sub-surface hydrologic and water quality models is needed to better understand, predict, and project how a warming climate will impact future hydro-climatic extremes and their associated impacts to freshwater.

Enhance resilience measures through flood risk research. Research on how a changing climate will impact future flood risk due to the combined changes in factors, such as extreme short-duration and longer-scale precipitation occurrence, with more complex spring floods are needed to inform resilience measures in the built environment and enhance emergency preparedness.

Enhance understanding of warm and cold-season droughts. Research on how a warming climate will impact the frequency, intensity, duration, spatial extent, onset, and termination of warm and cold-season droughts and associated water levels are needed to more effectively inform adaptive management approaches such as future scenario models, downscaling approaches, and agricultural-crop models.

Water balance, availability, and sustainability

Summary

Canada has a relatively large freshwater resource, but freshwater availability differs widely in terms of timing and quantity across the country. Changes in the water balance due to climate change have affected, and will continue to affect, freshwater availability. This creates challenges and increases vulnerability in our water management systems. Freshwater availability is governed by the processes of the water cycle, which vary widely in importance among different landscapes and watersheds. While there has been no coherent pan-Canadian assessment of future water availability, there is considerable information on how the water balance is changing across most of Canada. The loss of the cryosphere is pervasive. Changes in precipitation phase (snow now falling as rain) is becoming more prevalent in autumn, winter, and spring. Shorter snow-covered seasons mean longer periods and higher volumes of evaporation. The availability of water in streams, lakes and wetlands will subsequently change. The manifestation of this change is complex since it is highly dependent on the landscape, the size of the watershed, built infrastructure and the time period being considered. Adjusting to these types of changes requires analysis and modelling, based upon the best quality water balance data available. The transboundary nature of much of Canada’s freshwater necessitates better inter-jurisdictional teamwork in water research and prediction. Engagement of all key partners, beneficiaries, and stakeholders leads to more impactful water management outcomes and more resilient communities.

Key gaps and needs

Research water balance processes at the national scale. Research in predominant water balance processes as well as an examination of projected changes of streamflow and freshwater availability at the national scale is needed, and this knowledge needs to be more effectively incorporated into environmental prediction systems to improve projections of future water availability, vulnerability, and reduce uncertainty during decision-making.

Monitor hydro-climatic variables. Improved collection of high-quality hydro-climatic data are needed for advanced analysis and modelling to better understand and predict water cycle processes vulnerable to changes in water budgets and availability, as well as to support integration with water management models such as to inform water quality and quantity implications of resource developments.

Expand capacity to advance and integrate earth observations methods as a standard. Advancements in the integration of earth observation methods for retrieving water balance state and flux/flow variables in environmental prediction systems are needed to facilitate the assimilation of field, model, and remotely sensed hydrology. These advancements would drive an enhanced and comprehensive understanding of freshwater availability in Canada.

Water quality impacts in a changing climate

Summary

Climate change is altering water temperature, lake stratification and ice cover regimes, and precipitation patterns. In freshwater systems, these stressors influence physical, chemical, and biological processes that are linked to water quality including permafrost melting and development of thermokarst lakes, remobilization of legacy nutrients (phosphorus), brownification (increased loading of dissolved organic materials to water), and eutrophication and associated harmful algae blooms. These changes are impacting human health and ecosystem services in an ongoing fashion. There is a need for the development of a comprehensive and integrated approach to quantifying water quality on a national scale, as well as research on the systemic response to shifting communities and the subsequent changes to pathways of material and energy transport in aquatic food webs (e.g., the altering dynamics of nutrients, carbon, and contaminants). Moving forward, nationally coordinated mechanisms are needed to quantify the impacts of climate change on water quality in aquatic ecosystems at regional and national scales, including the co-development of data collection practices to obtain simultaneous climate-relevant and water quality information.

Key gaps and needs

Develop and maintain a national inventory of freshwater ecosystems. A national inventory of freshwater resources that characterizes baseline geology/hydrology and water quality for systems in major drainage basins is needed to better quantify changes due to climate drivers, as well as more seamlessly facilitate communication and collaboration between governments, academia, and stakeholders.

Integrate climate models to incorporate aquatic ecosystem health. Development of enhanced and integrated climatic, hydrologic, deterministic, and statistical models that consider water quality and aquatic ecosystem biodiversity (e.g., food web modeling) are needed to account for all interactions that occur within a freshwater ecosystem that could highlight why and how climate and land-use decisions are impacting hydrologic and lake mixing regimes.

Ensure continuance of long-term freshwater studies. Continued investments in basic, mechanistic research between environmental drivers and biotic responses (molecular, metabolic, ecological) that regulate water quality at various spatial scales are needed to effectively respond to complex issues around the predictive understanding of water quality and aquatic ecosystem health in Canada and inform effective and timely management actions.

Land-use and water-use changes

Agricultural-sourced stressors

Summary

Agricultural land use activities are impacting water quality, quantity, and aquatic ecosystem health in Canada. A changing climate will exacerbate these impacts. Issues relating to water quality in Canadian agriculture primarily relate to water quality impacts through fertilizers and pesticides, while those relating to water quantity involve having too little (drought) or too much (floods) of this resource. Increased precipitation extremes due to climate change result in increased leaching losses when high rainfall occurs after fertilizer application and before significant crop uptake. Conversely, extended and more severe drought events limit crop growth and nutrient uptake where excess residual nitrogen and phosphorus is lost after crop harvest when fall or spring rains occur. There is a need for enhanced research to support irrigated field mapping, spatial variability of soil erosion, effects of nutrient management scenarios, intensive greenhouse production, interactions of farming systems at a watershed scale, and best management practices. There is also a need for data generated at the producer level, representing irrigated fields at the national scale, and an expansion of the use of existing and new Earth Observation data streams. National space-based irrigation monitoring systems, priority setting for large waterbodies, and both sharing, and coordination of data are crucial. Moving forward, strong federal department coordination on the water continuum, with science committees for regional watersheds, enhanced integrated research with stakeholders, and relationship-building with Indigenous partners would more effectively inform and address these needs.

Key gaps and needs

Build on soil erosion knowledge supporting Best Management Practices. Increased knowledge of erosion spatial variability at watershed and landscape levels, including interactions between processes such as land-use change, wind and channelized erosion, and soil accumulation are needed to better inform the effects of implementing Best Management Practices on these processes.

Build on water quality knowledge supporting Best Management Practices. A more comprehensive understanding of impacts from existing Best Management Practices on water quality at a watershed scale is needed to ensure and enhance the timeliness and effectiveness of these practices on nutrient management and protection of aquatic ecosystems.

Leverage Earth Observation technologies. Adoption and consistent use of Earth Observation technologies and other data to create accurate annual maps of irrigated fields are needed to better understand spatial-temporal trends of changes and dynamics of Canada’s irrigated agricultural landscapes, ultimately contributing to more informed decision support tools and Best Management Practices.

Aquatic invasive species

Summary

Aquatic invasive species are a main cause of global extinction and are one of the leading and fastest growing threats to food security, human and animal health, and biodiversity. They significantly contribute to cumulative effects and multiple stressors, such as destruction of habitats (already impacted by habitat loss), urban runoff, and wastewater. Aquatic invasive species have been responsible for transformations and degradation of both inland and coastal wetlands, with impacts on the physical habitat structure and food web dynamics. In addition, invasive species have been found to carry parasites that can harm or kill native species. Climate change will continue to shift the range and abundance of these effects. Prevention and early detection measures are more cost effective and efficient than control measures and long-term management once aquatic invasive species have been established. Ongoing efforts include a focus on development of species and pathway risk assessments and tools as well as research, science advice, guidelines, and analytical support on detection tools such as environmental DNA—the analyses of DNA from environmental samples such as water to infer the presence of a species. Research questions related to aquatic invasive species are multidisciplinary and require support and input from a variety of sources.

Key gaps and needs

Mobilize the scientific knowledge to support preventative measures. A continued focus on risk assessments on the potential for organisms to arrive in Canada, including a focus on species and pathway risks with climate change considerations, is needed to effectively analyze, communicateand mitigate the risks of potential invasive species.

Drive the standard use of modern tools such as eDNA. Tools such as environmental DNA (eDNA) analyses, harmonised guidelines and standards, and accredited eDNA / forensic laboratories are needed to support cost effective and rapid early detection as well as management responses.

Hydropower stressors

Summary

The generation of electricity via hydropower is critical to Canada’s energy supply, but the damming of rivers often results in negative consequences. The transformation of fluvial habitats to lacustrine habitats (reservoirs) upstream of dams can alter flow regime, available habitat, thermal dynamics, and water quality. Upstream impacts also include changes to the composition of aquatic species, often with the loss of species who require a fluvial habitat to complete their life cycle. Further, bioaccumulation of contaminants such as mercury, due to flooding of dry land for the reservoir, continues to be a concern, particularly in boreal regions. The scale and magnitude of downstream impacts vary greatly and are influenced by the size and configuration of the dam, the operational regime of the facility itself, and the degree of alteration from the natural flow regime. River fragmentation affects the connectivity of habitats, impacting both resident and migratory fishes that depend on accessing upstream habitats for spawning, and causing injury or mortality from passing through the dam when moving downstream. There is growing understanding of how hydropower production can affect aquatic biota and habitat, and potential mitigation efforts to reduce such impacts. To better mitigate the impacts of hydropower on aquatic biodiversity and habitats, a focused effort on new technologies, such as micro-hydropower facilities or hydrokinetic turbines, have potential though still necessitate a better understanding of any potential cumulative effects of many small facilities as an equivalent replacement of one large dam. Research into innovative mitigation solutions for new and existing facilities deserves focus. Moving forward, research would greatly benefit from national coordination to ensure complementary issues can be addressed at broader scales, potentially providing solutions beyond specific sites. User-centred knowledge mobilization would greatly increase the value of the extensive research efforts by industry, and their consultants, for site-specific regulatory purposes.

Key gaps and needs

Support modernized hydropower technology. Research and assessments on new technologies such as micro-hydropower facilities and hydrokinetic turbines are needed to resolve stressors on aquatic ecosystem health caused by dams.

Research innovative mitigation techniques. Development and validation of innovative mitigation techniques on upstream, downstream, and fish passage impacts are needed to inform action, such as site-specific or broader regulations.

Facilitate national and multi-jurisdictional coordination. A coordinated multi-jurisdictional approach to connect and mobilize research and knowledge on common hydropower-related sustainability issues and impacts on aquatic ecosystem health are needed to improve the efficiency and effectiveness of actions, moving beyond the typical place-based or site-specific approaches on impacts and mitigations.

Aquaculture-sourced stressors

Summary

People eat more fish and seafood than natural sources can currently provide. Freshwater aquaculture supports the production of Rainbow trout, and increased production is needed to meet today’s demand. The feed used in aquaculture increases phosphorus levels (contributing to excess nutrients in freshwater environments) and reduces dissolved oxygen in and just above sediments in host water bodies. Highly localized effects especially to the benthic environment have been detected, but there are no suspected cases of broad scale environmental impacts to date. Halo zones of low-level nutrient enrichment in the benthic environment appear to extend beyond where depositional models would predict. However, the ecosystem implications of benthic nutrient enrichment within different Canadian freshwater systems are not well characterized or understood. Land-based aquaculture facilities also release effluents that have an impact on aquatic ecosystems. Several federal entities share responsibility for regulating aquaculture activities, and a variety of government and academic research efforts are underway to determine impacts on freshwater environments in Canada.

Key gaps and needs

Conduct nutrient-enrichment effects research on surrounding fish-farm sites. Research on the nutrient-enrichment effects surrounding fish-farm sites, such as characterization of site-specific dynamics, effects of changes in feed formulation on the benthic environment and primary productivity in surrounding waters, is needed to inform mitigation actions and decision-making in balance with the continued increase in production sites.

Conduct far field and cumulative impacts research. Far field and cumulative impacts research to examine carrying capacity of waterbodies are needed to support environmental sustainability and better inform the location of future developments as the aquaculture industry expands.

Freshwater fish habitat

Summary

Freshwater fish habitat is of environmental, economic, cultural, and spiritual value to all Canadians, including Indigenous Peoples. Habitat degradation and modification, aquatic invasive species, adverse effects of pollution and climate change are ongoing threats to freshwater fish habitat. Robust and collaborative freshwater habitat science is necessary to support policy development, regulatory decision-making, and the development of operational tools to support the implementation of the amended and modernized (2019) Fisheries Act. Dey et al. (2021) completed a comprehensive study that prioritized freshwater habitat research questions and noted that research is needed to better understand the impacts of individual stressors, as well as cumulative effects of human activities on freshwater habitats. In addition, there is a need to assess the effectiveness of habitat management measures to further support the conservation and protection of fish habitat across all jurisdictions. A standardized approach to freshwater habitat data collection and monitoring, as well as ensuring this information is made publicly available, is necessary to effectively coordinate freshwater habitat science activities across Canada.

Key gaps and needs

Leverage existing knowledge and deepen understanding of cumulative effects. Collaborative research on the impacts of individual stressors, cumulative effects of human activities on freshwater fish and fish habitat, and the effectiveness of habitat management measures is needed to better inform policy, regulatory decision-making, and management decisions.

Standardize freshwater habitat data collection, analysis, and monitoring approaches at a national level. The development of a cohesive, consistent, and nationally coordinated approach to freshwater habitat data collection, and analysis, as well as the development of national standards for freshwater habitat monitoring is needed for informed, evidence-based management decisions and to support comprehensive assessments of the effectiveness of habitat management measures.

Make the data publicly accessible and discoverable. A strengthening of efforts to make freshwater habitat data publicly accessible to scientists, regulators, and the public through new and existing open database platforms is needed to support freshwater habitat research, as well as coordination of efforts on the conservation and protection of fish and fish habitats.

Forest change

Summary

Forests dominate much of Canada’s landscape and are a critical source of freshwater. Forests play an important role in mitigating flood and drought risk, supplying drinking water, and supporting aquatic habitat and biodiversity. Forests are being impacted by a range of natural and anthropogenic stressors, such as climate change, wildfire, deforestation, and harvesting, which has consequences for freshwater. There is a need to better understand how forests are changing and the impacts of these changes on freshwater supply, habitat, and biodiversity. Moving forward, coordinated support to advance science on forest-water interactions is needed to address current and emerging issues. A focus on building dialogue and collaboration between Indigenous communities, forest and water scientists, managers, and stakeholders would help establish a national strategy on forest-water management. In addition, most knowledge on forest-water systems is from small experimental watersheds or consists of short data records that do not reflect long-term changes in forest and climate dynamics. A nationally coordinated approach for monitoring forest-water systems, particularly at scales relevant to management, would lead to better understanding and predictions for informing science-based management strategies. This approach would ensure that critical forest-sourced freshwater is sustained in a changing world. Given the extent of forest cover in Canada, there is the potential to leverage and manage forests as nature-based solutions for enhancing freshwater security in a changing climate.

Key gaps and needs

Investigate impact of forest change on freshwater resources and aquatic habitats. Given widespread influence of forests on Canada's water cycle, a better understanding of how forest change is impacting freshwater resources (including predicting impacts on drinking water supply, flood and drought risk, global carbon cycles, and aquatic and terrestrial ecosystem health) is needed to inform adaptation and mitigation efforts.

Coordinated national monitoring of forest-water systems at scales relevant to management. An integrated national monitoring approach that captures long-term changes to forest-water interactions and different watershed scales is needed for building robust models to predict future conditions.

Metals and mining

Summary

The mining industry has improved extraction, processing, and treatment technologies, but still relies heavily on the use of water. As a result, the mining industry’s consumption and release of water (e.g. tailings ponds effluents) increases stress on the surrounding freshwater ecosystems. Sources of freshwater contamination from mining include point sources (e.g., mine effluents) and non-point sources (e.g., acid mine drainage, dust emissions, accidental release). The mining industry is regulated at both the provincial/territorial and federal levels. For example, the metal and diamond mine effluent regulations (MDMERs, 2021) are put in place to limit the impact of effluents on the receiving environment and involve regular monitoring of metal concentrations in the effluent as well as its toxicity and environmental effects. Current research is focused on improving water recycling and usage in mining operations, as well as assessing treatment efficiencies under different climate scenarios that would lead to improved management of water volumes, a reduction in freshwater usage, a reduction of elements of concern released to the environment, and reduced risk to the aquatic environment. With regards to understanding the environmental impacts of mining on watersheds, significant data gaps still exist. For example, data to better understand how metals behave in mixtures, the toxicity associated with dietary exposures, and the cumulative impacts of climate change on metal fate and effects are needed. It is essential that research in these areas continues so we can ensure the development of a sustainable metal mining industry in Canada.

Key gaps and needs

Evaluate water recycling in the mining sector. Evaluation on how well treatments work under changing climate scenarios and optimization of the best available technologies are needed with the aim of reducing water use and contaminants released to the environment.

Improve the environmental relevance of risk assessments in mining areas. Understanding the behaviour of metals in mixtures, dietary exposures and the cumulative impact of climate change on water quality is needed for sustainable metal mining activities under a changing climate.

Coordinate environmental monitoring of mining-impacted areas. National and multi-jurisdictional coordination of the collection and analysis of water quality monitoring data across Canada is needed to improve the understanding of the environmental impacts of mining in a changing climate and support effluent regulations.

Groundwater consumptive issues

Summary

Over 30% of Canadians directly rely on groundwater for their drinking water and it is the main water supply for about 80% of Canada’s rural population. Although groundwater plays a key role in the water cycle as a year-round source of streams (providing a critical contribution during low-flow periods) and ecosystems such as wetlands in most of Canada, it has historically been understudied. Thus, the amount of groundwater stored in Canadian aquifers, their recharge rate, sustainable yield, and interactions with surface waters and ecosystems are poorly understood. Increasing populations result in more urbanization, agricultural intensification, and industrial operations. Combined with climate change, these stressors can impact the availability and quality of groundwater resources. Although Canada generally extracts groundwater at sustainable levels, local issues are increasing. Impacts to groundwater may take decades to be detected and may therefore be extremely difficult or impossible to remediate. Data are needed to better understand the dynamics of hydrogeological systems, assess sustainable use, and to support early detection of potential quantity or quality issues. Significant efforts are needed to improve methods and approaches that more efficiently and effectively assess groundwater resources including water quality characterization, water balances estimation, withdrawals, and sustainable flows. As surface water and groundwater are intimately connected and cannot be considered in isolation, data collection, analyses, and numerical models that integrate groundwater and surface water interactions, including atmospheric fluxes, land use change impacts, and climate change must be developed by multidisciplinary teams. Enhanced understanding of groundwater systems, as well as the impact of human activities, remains a crucial area of research to inform social and environmental issues for years to come.

Key gaps and needs

Close the knowledge gap. Deployment and maintenance of a national monitoring network, in collaboration with provinces, territories, and Indigenous groups, are needed for continuous data acquisition to better understand changes to groundwater dynamics influenced by climate change and human activities across Canada.

Make data discoverable and usable. Improved methods and approaches to help data collection and interpretation as well as the development and maintenance of public databases using national standards are needed to broadly better characterize aquifers with available data, ultimately to move water cycle-related data across freshwater domains (both surface and groundwater) to feed holistic modelling efforts.

Mobilize the science. Improved freshwater knowledge mobilization approaches, including technology and expertise that consider the needs of a broad range of audiences like policy makers and members of the public, are needed to foster dialogue to bridge regional concerns within the broader national context.

Contaminants and pollution

Emerging and legacy contaminants

Summary

The chemical industry is one of the largest industrial sectors in the world, and it is expected to grow fourfold by 2060. In Canada, as in many other countries, thousands of chemicals and substances are used in industrial processes and consumer goods, with additional chemicals being developed or imported every day. Legacy and emerging contaminants are of growing concern in the environment as they represent a major threat to both the environment and human health due to their potential toxicological effects and related risks to freshwater ecosystems in Canada. Emerging contaminants and legacy contaminants of emerging concern are widely present and distributed in the aquatic environment. Scientific knowledge on emerging contaminants has not yet been fully translated to support the development of evidence-based regulatory decision-making to protect freshwater sources, ecosystems, and human health. There is a need to identify and prioritize emerging contaminants and legacy contaminants of emerging concern, and to develop analytical tools, methods, and prediction models that describe their fate, transport, and transformations in the environment based on a life-cycle approach (e.g., production, consumption, and disposal routes).

Key gaps and needs

Strengthen identification and prioritization of new, emerging and legacy contaminants of concern. A sustained focus on identifying and prioritizing new emerging contaminants and legacy contaminants of emerging concern, including development of modernized analytical tools, methods, and prediction models is needed to better consider their fate, transport, and transformations in environmental assessments based on a life-cycle approach

Develop a strategy addressing the issue nationally. A whole-of-government approach to inform development of a national strategy for legacy and emerging contaminants in the environment, grounded in science, with data sharing and community-based monitoring, is needed to address emerging scientific and research knowledge gaps in a systematic, effective, informative, and timely manner.

Excess nutrients

Summary

Nutrients, predominantly nitrogen and phosphorus, are essential for plant growth in freshwater and determine productivity in most ecosystems. Urbanization, agriculture, and climate change result in excess nutrients in both surface and ground waters, beyond the sustainable limits of many ecosystems. This surplus of nutrients leads to eutrophication—a pervasive and nationally recognized threat to freshwater quality in Canada, while contamination of groundwater, used as a drinking water source for many Canadians, is also a concern. The degradation of freshwater due to excess nutrients reduces the services that freshwaters provide to Canadians. Examples of this degradation include changes to diverse freshwater communities to ones dominated by pollution-tolerant organisms, proliferation of toxic and undesirable algae that can contaminate drinking water supplies, limitations of recreational activities, fish kills, and subsequently increased economic burdens to Canadians such as through infrastructure costs and water treatments often experienced in rural communities. There is an urgent need for enhanced understanding of the effects of nutrients discharged from sources such as sewage lagoons, the impacts of legacy nutrient stores, analyses of nutrient uptake and retention in freshwaters, as well as research on nutrient ratios. Implementing essential activities such as groundwater monitoring and the development of early-warning indicators of ecological health for freshwaters are also needed. As sources of nutrients include municipal sewage, septic fields, agricultural activities, industrial practices, atmospheric deposition, stormwater ponds among others, there is a continued necessity for significant and effective multi-sector initiatives, leveraging existing efforts such as Living Labs or citizen science activities at the catchment level, and for these coordinated science efforts to address nutrient threats to freshwater ecosystems in Canada.

Key gaps and needs

Research nutrient discharge impacts on aquatic ecosystem health. Enhanced understanding of nutrient discharge, such as from wastewater treatment lagoons, on aquatic ecosystem health are needed to monitor impacts, and measure effects of mitigation including upgraded treatment facilities, to ultimately inform prediction and management practices.

Develop modernized early-warning nutrient indicators. Identification of early-warning indicators, leveraging modern advancements such as genomics and metabolomics, is needed to better evaluate and diagnose the effects of nutrients on aquatic ecosystem health.

Research nutrient ratios and linkages to aquatic ecosystem health. A comprehensive understanding of the effects of nitrogen to phosphorus imbalances (nutrient ratios) on freshwaters and the ecosystem services they provide is needed to determine the productivity and limits of freshwater ecosystems and support the development of early-warning indicators to mitigate detrimental impacts.

Cyanobacterial and harmful algal blooms

Summary

Cyanobacterial and harmful algal blooms are environmental and public health issues both within Canada and worldwide. While eutrophication is the most well-known trigger of these blooms in freshwater systems, other anthropogenic impacts provide opportunities for the proliferation of blooms. In addition, the species that comprise cyanobacterial and algal blooms have developed numerous mutualistic relationships with other microbes and phytoplankton, which may be important for their survival and dominance. Blooms are controlled by the synergistic effects of nutrient inputs, physical factors, and biotic interactions. Mitigation efforts largely rely on the reduction of nutrient inputs rather than physical or biological manipulation. At a national scale, data paucity and fragmented approaches to monitoring hinder the ability to promptly detect the occurrence of blooms and effectively communicate risks. Development of earth observation networks and sensor networks are promising avenues to expedite detection of blooms quickly and remotely. Furthermore, advances in ecosystem modelling, particularly from a predictive or forecasting approach may further improve the understanding around triggers of blooms and cyanobacterial toxin production. Additional efforts to characterize cyanobacterial toxins and their treatment may facilitate improved mitigation, such as at water intakes where blooms cannot be controlled quickly using conventional methods. The use of space-based earth observation is rapidly evolving and the expansion of tools like EOLakeWatch, in addition to new hyperspectral space-based observations will be necessary to address cyanobacterial and harmful algal blooms across Canada.

Key gaps and needs

Improve predictive modelling on the magnitude, intensity, duration, and locations of blooms. The capacity to predict systems at risk of blooms using mechanistic inputs is needed to better understand impacts of environmental drivers on future events, trajectories, as well as assess mitigation strategies.

Effectively detect and respond to cyanobacterial and harmful algal blooms. A national framework for a coordinated response to cyanobacterial and harmful algal blooms with prompt detection, spatio-temporal monitoring, identification, and reporting is needed to ensure comprehensive and inclusive scientific activities translate to effective, informed responses such as on risk management of potable water supply and sustainable recreation/economic activities.

Characterization and interactions of cyanobacterial toxins. An enhanced understanding of ecosystem-specific drivers of cyanobacterial toxins and their trophic-level interactions, including from benthic cyanobacteria, are needed to better inform water quality guidelines and ultimately support actions to protect ecosystem health.

Endocrine disrupting substances

Summary

Endocrine disrupting substances have diverse mechanisms of action and sources including agriculture, manufacturing, and consumer products. These chemicals often end up in waters across Canada where they can cause adverse health effects in organisms at low concentrations. Endocrine disrupting substances are found in many Canadian environments, including rivers and lakes receiving pulp mill effluents, municipal wastewater effluents, and historically contaminated areas of the Great Lakes. Species sensitivity and level of exposure can affect the potency of endocrine disrupting substances, and there are critical “windows of exposure” where changes to organisms can be irreversible. There is a need for validated test methods to assess multiple effects from endocrine disrupting substances. We need to better understand the complex endocrine effects of chemical mixtures and link these to changes at the population and ecological community levels. Moving forward, national coordination of endocrine disrupting substance detection, research, and regulations are needed so that we can protect Canadian aquatic environments from these chemicals in the future.

Key gaps and needs

Improve assessment methodology for endocrine-disrupting substances. Validated test methods to detect and investigate endocrine disrupting substances are needed to understand how they change population and ecological communities and better regulate them.

Continue efforts in understanding ecosystem responses. Knowledge building of Canadian ecosystems, basic reproductive biology of aquatic biota, and interactions of species within natural environments are needed to better understand the global effects of endocrine disrupting substances and other chemicals.

Pesticides

Summary

Global pesticide use has resulted in widespread environmental degradation, persistent contamination of surface and ground waters, bioaccumulation of these contaminants in food webs, and unintended impacts on non-target species (e.g., bees, aquatic insects, and fish). Recent studies continue to highlight the nuances of the toxicity and fate of both individual and mixtures of pesticides in the environment with variations in pesticide use dependant on the economic sector, intended target, regional variations in practices and, of course, climate. Thus, not only do efforts in this area need national coordination but also regionally relevant approaches to reflect provincial and territorial guidance, while recognizing that pesticides serve a purpose and are widely used for controlling and eliminating pests. A more holistic understanding of pesticides that considers different sectoral needs and that includes mixtures relevant to agriculture, transportation, forestry, and heavy industry is warranted. Further, a more sophisticated approach to understanding that chemicals are present in the environment as mixtures and not as individual substances and further, that these mixtures may interact, will be essential in order to account for risks associated with other environmental gradients such as climate change. Moving forward, inter-departmental support and research efforts on the environmental effects of pesticides will continue to be required while new investments in data platforms, infrastructure, and expertise will be needed for better coordination of pesticide monitoring and programming across Canada.

Key gaps and needs

Research the long-term impacts of pesticides in aquatic ecosystems. Research on pesticide impacts along with their interactions with multiple stressors (e.g., eutrophication) is needed to globally assess their negative effects on wildlife populations.

Improve understanding of pesticide mixtures. Research on the ability of mixtures of pesticides and other substances to cause toxic effects in aquatic environments is needed in support of regulatory needs for multiple substances such as to help evaluate the relative contribution from each compound toward the overall toxic effect of the mixtures.

Support national coordination of pesticide monitoring. Coordinated national monitoring approaches that are consistent (e.g., autosampler use at weekly, monthly, annual basis), with publicly accessible data outputs, are needed to increase the understanding of pesticides in the environment.

Plastics

Summary

Since the 1950s the volume of plastic has increased, becoming ubiquitous in our natural environment. More recently in Canada, microplastics have been reported in the benthic zones of Canadian waters, in large lakes such as Lakes Winnipeg, Superior, and Erie, and large quantities of microplastics have been found in Arctic deep-sea sediment, subsurface sea waters, and in ice cores. Improperly managed plastic waste is now found in shoreline areas, surface waters, sediment, soil, groundwater, indoor and outdoor air, drinking water, and food. It is likely that plastic pollution will increase in the future. In Canada, plastic waste includes single-use bags and bottles, microplastics, such as fragments of single-use plastics, microbeads, and fibres, and smaller nanoplastic particles. Since plastics degrade very slowly, they remain in the environment for an exceedingly long time. In water bodies, plastics threaten ecosystem function, biodiversity, and habitat integrity. Plastics are often ingested by wildlife causing harm or suffocation. Although there are a number of ongoing research and development initiatives to reduce plastic waste, much of the work is done in isolation and would benefit from increased coordination, collaboration, knowledge mobilization, and capacity building to make better use of existing resources and expertise. Development of standardized methods for sampling, quantifying, characterizing, and evaluating the effects of macro and microplastics, as well as consistent monitoring efforts to include poorly characterized environmental compartments, are needed.

Key gaps and needs

Increase systematic and standardized surveillance and monitoring activities. The development of standardized methods for sampling, quantifying, and characterizing plastics (including micro and nanoplastics) in major rivers and lakes across the country is needed to capture information related to their presence, abundance, and trends that support consistent assessments of relative risks and areas of concerns across Canada.

Enhance characterization of occurrence and impacts of plastics. Research on the sources, transformation, exposure, and effects of plastics on aquatic ecosystem health is needed to better understand the fate and effects of plastics in the environment.

Improve assessment of plastic accumulation in, and transfer by, aquatic biota. Studies that examine the biomagnification, bioaccumulation, and bioconcentration of plastics in aquatic ecosystems are needed to enhance the understanding of their food web impacts and their cumulative effects on aquatic organisms.

Municipal wastewater effluents

Summary

Municipal wastewaters are complex mixtures that can have a variety of impacts on aquatic environments. Direct release of municipal wastewater, consisting of liquid waste and sewage discharge, is the largest source of these effluents into freshwater ecosystems in Canada. Despite improvements in treatment processes, some freshwater ecosystems continue to be negatively impacted by effluents with additive and synergistic effects on aquatic communities. Wastewater treatment plants are not designed to remove trace contaminants (e.g., metals, legacy contaminants, and emerging substances of concern including chemical additives and pharmaceuticals), which remain in wastewater effluents and end up in their receiving environments. Federal regulations inform maximum limits of specific parameters in effluents to protect freshwater ecosystems. Furthermore, the development and implementation of new treatment plant technologies focus on system capacity and improved effluent quality, and this can change the chemical matrix and its potential suite of effects. There is a need for a better understanding of mixture effects as well as cumulative effects, such as genotoxicity and endocrine disruption, from multiple effluent discharges. Moving forward, strong national research coordination on contaminant mixtures is warranted, by developing the tools and approaches needed to address the risks posed by contaminants and their transformation products released from municipal wastewater plants.

Key gaps and needs

Increase understanding of the ecotoxicological impacts of emerging toxics. Research to evaluate the fate and effects of emerging toxics as well as their transformation products from natural processes in receiving environments and wastewater-engineered treatment is needed to inform and support new, effective management practices for these emerging substances.

Improve risk assessment from chronic exposure to municipal effluents. Enhanced research focus on chronic effects (such as genotoxicity and endocrine disruption) is needed to better evaluate released contaminants from both wastewater treatment and natural transformation processes.

Assess the chemical mixture effects and cumulative impacts of stressors. Research for comprehensive assessment of combined contaminants and stressors (e.g. pathogens and viruses) from multiple effluent discharges is needed to prevent ecological and human health problems by taking a more holistic aquatic ecosystem approach.

Urban runoff

Summary

The capacity of wastewater treatment plants is limited in Canadian municipalities, which has resulted in increased untreated waters being released into the environment. This untreated urban wastewater consists of mixtures of contaminants that can produce adverse toxic and cumulative effects. Urban runoff resulting from the release of raw sewage, stormwater, and resuspended sewer sediment poses an increasing challenge in the face of population growth and increasing urbanization. Accelerating climate change will lead to more frequent and intense rainfall, posing increased challenges to wastewater treatment capacity. Existing regulations under the Fisheries Act protects fish by focusing on key toxic parameters, such as ammonia. The discharge of untreated wastewater highlights areas where new technologies could be designed to better manage the impacts of urban runoff. There is a need to develop ecotoxicological approaches, including chronic tests for long-term exposures to untreated wastewaters and non-lethal effects. Moving forward, coordinated efforts are needed to fully assess composition and environmental impacts of contaminant mixtures released from untreated wastewater and exposure conditions, such as intensity, period, and duration of discharge events.

Key gaps and needs

Increase understanding of the impacts of untreated wastewater. Research on the fate and effects of contaminants releases caused by more frequent and intense rainfall events is needed to evaluate the environmental consequences of challenged wastewater treatment capacity under a changing climate.

Improve the assessment of multiple stressors and cumulative effects. Research on interactions and combined effects of contaminant mixtures and stressors is needed to fully assess environmental impacts of multiple effluent discharges within the same watershed.

Enhance the integration of effect-based research with hydrodynamic modelling. Research on environmental factors controlling urban runoff variability in water quality and quantity is needed to better manage the impacts of urban runoff.

Chemical mixtures

Summary

Real-world mixtures contain combinations of existing pollutants, contaminants of emerging concern, and vast quantities of unknown substances. Mixtures exert real-world effects in freshwater ecosystems in Canada and around the world. The science on how chemical mixtures of concern for freshwater systems are defined, identified, and investigated, has significantly evolved over the past decade. Effects-based approaches to detect mixtures of concern have been pioneered in Canada, gradually shifting away from purely single-substance assessments. There is a need for regulatory agencies around the world, including in Canada, to recognize the necessity to address these issues, such as cumulative exposures and effects. Combined effects from multiple chemicals and sources have not been routinely or adequately assessed; therefore, there is a major need to enhance understanding of environmental chemical mixtures from chemical, toxicological, and ecological perspectives. Moving forward, mixture assessment efforts should be coordinated nationally to progress beyond regulatory and policy silos to support Canada in detecting, prioritizing, and swiftly addressing current and future threats posed by real-world mixtures, as well as new chemicals of emerging concern, on aquatic ecosystem health.

Key gaps and needs

Address cumulative exposures and effects of chemical mixtures. Better understanding of chemical mixtures in the environment and how they react and impact the environment is needed to consider the combined effects from multiple chemicals and sources in risk assessments.

Develop incentives for innovative approaches. New management and assessment approaches contributing to a circular economy are needed to nationally manage chemical mixtures and keep freshwater ecosystems free of a variety of harmful substances.

Enhance capacity to detect and characterize chemical mixtures. Laboratory capacity and expertise development are needed to address the present and future threats of chemical mixtures on aquatic ecosystem health in general and in support of government priorities.

Cross-cutting challenges

Multiple stressors and cumulative effects

Summary

Stressors are rarely present in the environment as single substances. Often, a mixture of stressors is present, and the components of these mixtures can both individually and collectively impact freshwater ecosystems. Incremental effects resulting from multiple stressors can also be ‘cumulative’ such that these effects can be significant even if the effects of each individual substance, when evaluated individually, are negligible. Impacts are also not necessarily restricted to chemicals—invasive species, parasites, predators, and other interdependent members of food webs can contribute to cumulative impacts in ecosystems. Further, although an estimated 60% of Canada’s freshwater supply flows north, the state of water quality in Canada’s vast northern ecosystems is largely unknown and rarely surveyed. Given the cost and logistical constraints of working in the Canadian north, the assessment of freshwater quality, including multiple stressors and cumulative effects, is only feasible in partnership with local Inuit, First Nations, and Métis communities. Meaningful community partnerships may also facilitate broadening the scope of work beyond siloes of expertise or program areas and thereby integrate cumulative effects of environmental gradients such as climate change. Moving forward, Canada’s freshwater ecosystems require wholistic, interdisciplinary, and co-developed research on multiple stressors, and by extension on cumulative effects, to protect this most precious resource for future generations. Strong interdisciplinary and co-developed research in partnership with communities will greatly accelerate meaningful gains in this area and will ultimately be needed to successfully manage risk moving forward.

Key gaps and needs

Prioritize science on multiple stressor processes in both surface and ground waters. Interdisciplinary scientific efforts including targeted monitoring networks and the development of new or improved mechanistic models and actionable tools to link impacts of multiple stressors on surface and ground waters are needed to facilitate greater understanding of local diversity with respect to cumulative processes (e.g. climate change, underlying geology, and permafrost thaw) and impact thresholds.

Collaborate on toxic effects of mixtures of substances. Improved understanding of toxic effects of mixtures of substances is needed to overcome challenges in scarcity of monitoring data in some regions, poor analytical detection limits for some pollutants, and multiple modes of action on different components of the food web.

Strengthen the water quality focus in the North. Inclusive research, modelling, monitoring, and reporting on the state of water quality in Canada’s vast northern regions is needed as approximately 60% of Canada’s freshwater supply flows to this region which is also home to many Indigenous communities.

Develop assessment approaches that consider cumulative effects. Development of cumulative effects assessment approaches at the catchment level that emphasize integrated watershed management, including scientific support in the design stages, are needed to effectively consider multi-faceted cumulative effects scenarios while continuing to address priority stressors in an ecological context.

Maintaining aquatic biodiversity

Summary

Measuring and protecting the biodiversity of aquatic ecosystems in Canada continues to be essential to support wise stewardship, maintain critical ecosystem services provided by freshwaters to Canada’s population, and promote resilience to ongoing global climate change processes. However, a rapidly changing climate in regions across Canada is predicted to dramatically alter the biodiversity in Canadian freshwater ecosystems through modifying thermal, precipitation, and hydrology regimes, eutrophication, brownification, landscape and land cover changes, habitat loss, reduced ice cover, and permafrost thaw. There is a need for consistent and comparable observational biotic data at a national scale to assess the impacts of rapid climate warming on biodiversity and linkages to ecosystem functions. Impacts of climate change on lower trophic level biodiversity and food web functioning, including microorganisms, is critical given their profound impact on ecosystem health and sustainability, greenhouse gas emissions from natural aquatic systems, and human health implications. Moving forward, national coordination for consistent collection of biotic data, especially within regions most vulnerable to climate change, along with nationally validated tools and methods to support freshwater biodiversity assessments that can be evaluated for integration into existing national programs (e.g., the National Water Quality Modeling Framework, Canadian Aquatic Biomonitoring Network and Sequencing the Rivers for Environmental Assessment and Monitoring), are needed. Lastly, there is a need to better understand Indigenous perspectives on biodiversity change through historical contexts and to address current concerns.

Key gaps and needs

Consistently monitor species-level biodiversity in vulnerable regions. Consistent, standardized, and comparable national data on the genus and species of organisms in the most vulnerable regions (e.g., landscape undergoing thawing permafrost) is needed to avoid potential loss of freshwater ecosystem services by reducing challenges associated with evidence-based species conservation targets and development of adaptation and mitigation measures.

Broaden understanding between biodiversity and ecosystem function relationships. Scientific efforts to assess the impact of warming on ecosystem function and how that influences biodiversity is needed to improve modelling, planning, and adapting to environmental change.

Braid and weave Indigenous science and knowledge into biodiversity research. More comprehensive and respectful understanding of how changing biodiversity impacts Indigenous communities, as well as braiding of Indigenous science and knowledge on biodiversity trends in historical and current contexts are needed to more effectively inform conservation planning and support Indigenous communities that are significant end users of biodiversity impact data.

Stressor impacts on ecosystem services

Summary

Freshwater ecosystems in Canada support a range of critical ecosystem services, such as food, filtered water, and clean air. Canadians rely on these services for their health and well-being, and thus the protection of these services is essential to provide environmental and economic sustainability. Canada's freshwater ecosystem services are impacted by many global change drivers such as climate change and contaminant emissions. Despite their importance, many of these services remain unrecognized and difficult to measure, and thus they remain difficult to incorporate into management planning. Moreover, the role of critical ecosystem functions that provide services to broader biodiversity is poorly studied. Therefore, an urgent need exists to develop case studies involving cross-departmental and cross-disciplinary projects that place ecosystem services at its centre, focusing on Nature-Based Solutions for delivery of a One Health approach. Co-development mechanisms to build ecosystem services research with Indigenous groups and other stakeholders are needed along with greater efforts to incorporate ecosystem services in strategic thinking, as well as infrastructure and tools for monitoring that supports environmental protection. Moving forward, implementing total ecosystem protection, including freshwater, and traversing mandates requires a whole-of-government solution. This approach would help to guide monitoring assessment needs and protection requirements, strengthen identification and quantification of strategic ecosystem services provided by Canada's freshwaters, and leverage the use of ecosystem services data and information.

Key gaps and needs

Evaluate the state of critical ecosystem functions. Research to assess the state of critical ecosystem functions, which underpin services, many of which cannot easily and usefully be measured at scale, are urgently needed to improve restoration practice in freshwater ecosystems, and thus sustain or improve their resilience.

Support large interdisciplinary, cross-jurisdictional research teams focused on ecosystem services. The development of large, diverse, cross-disciplinary, cross-jurisdictional research teams, including Indigenous communities and citizen science groups are needed to properly assess interconnectedness and interdependencies inherent in many ecosystem properties and processes which underpin ecosystem services at a national scale.

Develop a set of ecosystem services indicators. Informative, inclusive, and focused ecosystem services indicators are needed to communicate the success or failure of ecosystem management projects and will help reduce the environmental footprint of future developments.

Management of environmental flows

Summary

Environmental flows describe the timing, quantity, and quality of freshwater flows and water levels needed to sustain freshwater ecosystems and the ecological services, sustainable livelihood, and well-being they provide. Freshwater flows and water levels vary naturally reflecting geography, climate, time of the year, and extreme events. Human activities and increasing water demand further alter the flow of freshwater (e.g., through hydropower production or water abstraction for agriculture). Alterations can impact the attributes of a river necessary to sustain healthy freshwater ecosystems, including physical (e.g., bank erosion, loss of floodplains) and ecological (e.g., changing environmental cues for aquatic plants and animals) conditions. These impacts to environmental flows can also be made worse by climate changes that result in changes to snowmelt timing and amount, increased extreme precipitation events, and periods of drought. Improved understanding of the changes and patterns in river regimes through environmental flow assessments can significantly help water management and planning for the future. Experts are currently developing ways to connect information between environmental water flows, ecology, socio-cultural, and governance at the watershed level. This approach pairs the societal values with environmental needs. Although more complex, these methods are being continually improved, such as to reflect the ongoing climate change challenge. Addressing these research needs and informing decisions requires innovations in monitoring and research, such as DNA-based sampling to assess aquatic ecosystem health for flow-ecology relationships and applying remote sensing approaches to quantify freshwater.

Key gaps and needs

Braid Western and Indigenous science. Development and application of holistic environmental flows frameworks at the watershed and regional scales that bring both western and Indigenous science together are needed to more inclusively inform sustainable flow management.

Validate novel rapid hydro-ecological assessment methods. Improved geography and mapping tools, including remote sensing, are needed to understand the pan-Canadian water use and allocation to develop and validate novel rapid hydro-ecological assessment methods for testing of flow-ecology relationships within environmental flow approaches.

Develop an enhanced freshwater assessment network. An enhanced freshwater assessment network that pairs hydrometric, water quality, and biological monitoring sites is needed in order to identify and address research gaps in the preservation, protection, and management of freshwater ecosystems.

Conclusion and next steps

From both this overview and the Freshwater Science Workshop, there was broad acknowledgement that better communication, connection, and collaboration is crucially needed to address the complex challenges to freshwater environments in a changing climate that also impact Canadians. This effort would be between federal departments with interlinked mandates, as well as provincial, territorial, and Indigenous governments, academia, non-governmental organizations, communities, industry, and other stakeholders. Understanding and applying scientific knowledge on aquatic ecosystems in Canada is at the foundation of effective policy and freshwater stewardship. So, it stands that robust, inclusive, and collaborative freshwater science is fundamental to drive evidence-based decision-making.

Leveraging freshwater science for decision-making necessitates modernized mechanisms and expertise to effectively translate and mobilize this knowledge to a targeted audience when they need it and in a way that is actionable. Enhanced two-way communication of scientific activities, knowledge, and advice among knowledge holders and science-users across federal science-based departments and agencies, with other governments, in collaboration with experts, and respectfully representing the distinct and diverse Indigenous perspectives and knowledge systems is needed. This enhanced communication capacity would share and link complementary efforts and further leverage interdisciplinary collaborative opportunities to address Canada’s key freshwater challenges. Therefore, this Synthesis may be viewed as an opportunity to advance new questions, challenges, and opportunities to inform the discussion of integrated freshwater science, responsibility, stewardship, management, and action with key partners across Canada.

There are five foundational elements that have been repeatedly raised as key outcomes to action from the Synthesis:

1. National science coordination to guide multidisciplinary and interdisciplinary collaboration on pan-Canadian priorities and needs.
2. User-driven freshwater science to support distinctive watershed, regional, and local priorities within a national frame.
3. User-centric knowledge mobilization as an integrating mechanism of tools and experts to better connect, translate, and reflect the needs of freshwater science-users in Canada.
4. Digital tools, critical and innovative infrastructure, and standards to enhance freshwater science as well as operationalize the connectivity and mobilization of freshwater knowledge.
5. Bridging, braiding, and weaving of Indigenous science and knowledge to respectfully represent the distinct and diverse Indigenous perspectives and knowledge systems.

While the Synthesis is not intended to be a definitive collection of every freshwater issue facing our country, it provides a launching point for an opportunity to develop a National Freshwater Science Agenda.

This next step would be a means to focus collaborative and coordinated freshwater science to inform decision- and policy-makers. It will prioritize, align and enhance coordination of inclusive freshwater science in Canada and be a roadmap for investors, doers, and consumers of freshwater science in Canada. Ultimately, this Science Agenda will advance freshwater science knowledge in Canada, starting with the most pressing needs from a pan-Canadian perspective, while reflecting diverse knowledge systems and regional priorities.