Science Advisory Report 2020/030
Science Advice for Pathways Of Effects for Marine Shipping In Canada: Biological and Ecological Effects
- Vessels involved in commercial marine shipping in Canada engage in the movement of goods or people by sea on the Arctic, Atlantic, and Pacific oceans. In response to a request by Transport Canada, DFO Science Branch developed a suite of Pathways of Effects (PoE) conceptual models for marine shipping in Canada.
- Pathways of Effects (PoE) conceptual models describe the pathways (linkages) between human activities, associated stressors, and their effects on endpoints. They have been developed to be broad enough to be adapted for application in a range of environments and locations. PoE conceptual models are supported by text describing each pathway linkage based on available scientific literature or expert opinion. Indigenous and local knowledge was not used in this current work.
- PoE models are useful tools for the scoping phase of a variety of environmental assessments, such as ecological risk assessment, environmental impact assessment, and cumulative effects assessment, as they clearly outline activities and stressors and clarify connections between human activities and potential effects on ecological endpoints. While some endpoints have been identified for illustrative purposes here, the assessor is responsible for comprehensively scoping the specific endpoints (e.g., valued components) and stressors to be included in the assessment.
- PoE models do not include any evaluation of the relative or absolute impact from these activities on specific endpoints; this would occur in a subsequent assessment step, such as risk assessment.
- This systematic review of the effects of shipping-associated activities on marine ecosystems describes PoE models for five sub-activities (anchoring and mooring, vessel at rest, grounding and sinking, movement underway, and discharge) and linked stressors. Tables of evidence (based on literature review and expert opinion) are provided to describe broad-scale effects to generic ecological endpoints.
- Each sub-activity was described by using one or more PoE models, to enhance manageability and understanding of the different PoE components. Despite this separation for practical purposes, there may be considerable inter-relationship and overlap, and it would be an oversimplification to consider each sub-activity model in isolation without acknowledging these connections among elements of the suite of models.
- Sub-activities and stressors were determined by assembling activity and stressor terms developed through DFO risk assessment processes and cross-referencing Transport Canada's initial national online engagement outcomes, undertaken at the outset of Transport Canada's Cumulative Effects of Marine Shipping initiative. Stressor effects were categorised at a broad scale (change in fitness, mortality, and change in habitat) to ensure consistency in structure and applicability across regions. Endpoint examples used were broad, generic ecological examples based on DFO Pacific Region's vulnerability assessment groupings.
- Stressors and their broad-scale effects are the focus of this advice, rather than the endpoint examples provided, which are not comprehensive, and were chosen to illustrate how stressors may interact with features of the marine environment but caution is advised when interpreting the outlined endpoints. In an assessment, users choose from many candidate endpoints, which can be specific to the region, or area of interest. The goal in developing these endpoints was that they adequately describe the effects of a stressor while remaining generic enough to be applicable across Canadian regions.
- Scientific evidence to confirm potential effects on endpoints was not found for a small number of effects described in the PoE models, with the time and resources available. An absence of evidence does not mean that there is no effect and regardless of the body of evidence available, any potential linkage that could be substantiated by literature or expert opinion was included in the PoE, in keeping with the precautionary approach.
- The scope of this work includes domestic and international marine shipping that occurs in the marine and coastal waters (including estuarine and intertidal environments) of the Arctic, Atlantic, and Pacific oceans of Canada. Each of these oceans comprise three bioregions related to biogeographic differences in ocean conditions and depth. Ice cover is only experienced in the Atlantic (seasonally) and the Arctic (both seasonally and year-round). Canada's large freshwater shipping industry is considered only to the extent that it interacts with the marine environment.
- Activities undertaken by vessels other than the movement of goods or people are not considered in this document, such as fishing, seismic surveying, dredging, port operations (e.g., when at-berth and while berthing). Non-commercial vessels (e.g., recreational vessels) are also not specifically included in these models. This work does not examine the effects of shipping activities and stressors on elements of human well-being, but is restricted to marine biota and habitats in coastal environments.
- Cumulative effects from multiple stressors, stressor interactions, and indirect effects (such as those associated with climate change) were not included in this work; however, these undoubtedly occur and are important considerations when using the PoE models in an assessment, or when implementing an ecosystem-based approach to management.
- The conditions, such as the baseline(s) against which change is measured has not been defined in the PoE models, but should be clearly specified and defined during an assessment phase.
- This work describes potential pathways of effects of marine shipping and synthesises evidence for effects based on current levels of understanding and regulations. As additional evidence is obtained over time, understanding of the effects and impacts will change, along with the environmental (e.g., climate), technological, and social (e.g., management measures, legislation, and regulations) factors that influence them. The shipping PoE models should be considered "evergreen" and should be reviewed and updated when our understanding of these factors changes.
- The PoE models for marine shipping were developed as a tool to examine effects on ecological endpoints, but the tool may be adapted for social, cultural, and economic endpoints.
This Science Advisory Report is from the November 19-21 2019 national peer review of Science Advice for Pathways of Effects for Marine Shipping. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.
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