Research Document 2019/048
Ecological Risk Assessment for the Effects of Human Activities at the Hecate Strait and Queen Charlotte Sound Glass Sponge Reefs Marine Protected Area
By Hannah, L., Thornborough, K. and Thiess, M
Abstract
The Hecate Strait and Queen Charlotte Sound (HS/QCS) Glass Sponge Reefs were designated as a Marine Protected Area (MPA) in February 2017 (SOR/2017-15). In order to adequately protect and manage the HS/QCS Glass Sponge Reefs MPA (HS/QCS MPA), a comprehensive inventory and risk assessment of the human-based activities and stressors likely to interact with the ecosystem is required. In this work, the Level 2 semi-quantitative level of the Ecosystem Risk Assessment Framework (ERAF) developed by O et al. (2015) is applied to the HS/QCS MPA in order to determine relative risks to the ecosystem from anthropogenic activities. The scoping phase identified ten Significant Ecological Components (SECs) to appropriately represent the HS/QCS MPA: 6 species, 2 habitats and 2 community SECs, along with a comprehensive list of relevant anthropogenic activities and associated stressors occurring within the MPA. The application of the risk assessment provides prioritized lists of SECs and stressors on a relative scale, based on their estimated cumulative risk (to SECs) and potency (of individual stressors). The identification and prioritization of SECs and stressors is vital for the selection of risk-based indicators, and ultimately the development of monitoring plans. The SECs with the highest estimated cumulative risk scores were the Sponge Garden Habitat SEC, and the four sponge Species SECs (A. vastus, R. dawsoni, H. calyx, and F. occa). The stressors with the highest estimated scores for potency (additive cumulative risk by stressor) were oil from oil spills (Vessel Traffic), sediment re-suspension from bottom trawling (Fishing) and removal of biological material from mid water trawls (Fishing). The uncertainties identified by the risk assessment can inform Oceans Managers of existing knowledge gaps and help to identify priorities for monitoring. The highest uncertainties were associated with contamination from both acute oil spills and chronic low-level discharges, indirect effects from bottom trawling near the MPA and introductions of aquatic invasive species from grounding of vessels. Notable improvements made in this application of the ERAF include: inclusion of supplementary (glass sponge reef-specific) considerations during the species SEC scoping phase, use of truncated normal distributions to estimate uncertainty, and more precautionary treatment of low risk-high uncertainty stressors. As noted in other ERAF applications, assessment of Community/Ecosystem Property SECs continues to be a challenge in this context, given the current state of knowledge of the glass sponge reef ecosystem. Overall, the approach was deemed successful as a first iteration, and the Level 2 semi-quantitative ERAF was considered effective to provide preliminary information to managers and to inform the development of risk-based indicators. Though updates have been incorporated into this assessment, the scoping and scoring for this assessment was originally carried out in 2014-2015, before MPA designation. In light of the amount of new research currently being generated on this ecosystem, it is strongly recommended that a subsequent iteration be completed as soon as feasible. Suggested updates and improvements to be incorporated in the next iteration are summarised in this document.
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