Canada’s oilsands are a vast energy resource, the development of which has afforded enormous economic opportunities to Canadians. Oilsands bitumen extraction has been historically water-intense, leading to substantial volumes (~ 400M m3) of associated oil sands process affected water. This stockpiled water and solid/semi-solid tailings are complex mixtures of water, hydrocarbons, polar organics, salts, and clays that can all contribute to toxicity and treatment complexities. Potential oilsands impacts are further complicated by upgrading and flowability treatments, where bitumen is upgraded to synthetic crude or diluted for transport, where each present distinct associated risks. The variability in products, by-products, and compositions of associated toxicants contributes to a rich research landscape from associated toxicity, remediation, reclamation, and environmental monitoring activities. Despite decades of research, critical knowledge gaps remain in linking complex mixture chemistry to toxicological outcomes and the performance of treatment technologies. Regulatory decision-making requires integrated understanding across chemistry, toxicology, and engineering disciplines This proposed session will focus on: i. Advancing understanding of complex mixture characterization and drivers of toxicity.  ii. Bridging laboratory toxicity findings with field-scale monitoring and reclamation outcomes.  iii. Highlighting advances in treatment technologies and mitigation strategies.  iv. Fostering interdisciplinary dialogue between chemists, biologists, toxicologists, engineers, regulators, and industry scientists.

Indigenous Knowledge is recognized as holistic, site-specific, and deeply meaningful to place; however, Indigenous Knowledge and data have often been excluded from scientific studies due to the perception of “inadequate quality” and the observational nature of data. Recently, government agencies and funding programs have started to encourage the incorporation of Indigenous Knowledge into scientific research, but a significant question remains unanswered: how do researchers ethically and effectively weave knowledge systems together? As environmental practitioners develop novel and robust methods of research, questions regarding data sovereignty, the use of Indigenous Knowledge, and data in shared-decision making and public policy are beginning to emerge, especially within interdisciplinary circles. In this session, reflections on the successes and challenges of intersecting knowledge systems in the context of data sovereignty and ecotoxicology are encouraged with a goal of discussing how to implement programs with a wholistic perspective. We welcome quantitative and qualitative studies that involve consultation, knowledge sharing, training, or research with Indigenous communities.

Marine ecosystems—including coastal, estuarine, and openocean environments—are increasingly exposed to complex mixtures of anthropogenic contaminants and accelerating climatedriven environmental changes. Coastal regions, in particular, receive inputs from wastewater, industry, agriculture, maritime activities, and river systems, introducing diverse contaminants such as hydrocarbons, pesticides, nutrients, metals, microplastics, PFAS, pharmaceuticals, and other emerging chemicals of concern. Concurrently, climate stressors including ocean warming, acidification, hypoxia, and shifting salinity regimes can alter contaminant bioavailability and modify organismal responses, resulting in additive, synergistic, or antagonistic effects that complicate ecotoxicological assessment. An emerging area relevant to marine ecotoxicology is the development of marine carbon dioxide removal (mCDR) technologies, including ocean alkalinity enhancement, and direct ocean carbon capture processes. While these approaches may contribute to climate mitigation, they may also alter water chemistry or introduce novel materials, creating potential ecological risks that remain poorly understood. This session invites research spanning molecular to ecosystemlevel responses across all marine taxa and habitats, using in vitro, in vivo, field, monitoring, and modelling approaches. By integrating studies on novel marine methods, contaminants, environmental stressors, and mCDR, this session aims to advance mechanistic understanding, inform environmental risk assessment, and identify critical data gaps to support the protection of marine species and ecosystems.