Terms of Reference

Ground-truthing the final set of suspected sponge reef complexes in Howe Sound: Reef delineation and status assessment

Science Response Process – Pacific Region

February 19, 2020
Nanaimo, British Columbia

Chairperson: Anya Dunham

Context

Through the Strait of Georgia Glass Sponge Reef Conservation Initiative, Fisheries and Oceans Canada (DFO) has been working to identify and mitigate the impacts of bottom-contact fishing on glass sponge reefs in the Strait of Georgia and Howe Sound. Glass sponge reefs are unique habitats found along the Pacific coast of Canada and the United States with intrinsic, ecological, and economic value. They provide a link between benthic and pelagic environments, play an important role in carbon and nitrogen processing, act as silica sinks, and support diverse communities of invertebrates and fish (Cook et al. 2008, Marliave et al. 2009, Chu and Leys 2010, DFO 2018, Dunham et al 2018a,b).

Over the past 15 years, a number of glass sponge reef complexes have been discovered and mapped in the Strait of Georgia and Howe Sound using remote sensing (Conway et al. 2004, 2005, and 2007) and standardized visual survey methods (Dunham et al 2018a,b). Previous DFO Science initiatives, carried out in collaboration with Natural Resources Canada and conservation organizations, delineated glass sponge reef polygons, assessed their condition, and recommended assessment and monitoring methods (DFO 2018; Dunham et al 2018a,b). The resulting science advice formed the scientific basis for the implementation of 9 bottom-contact fishing area closures in 2015, followed by eight closures in 2019 (DFO 2019).

At the time the last set of closures was implemented in March 2019, nine additional areas in Howe Sound were described as possible sponge reefs based on diver observations or geological records, but datasets available at the time were not sufficient to confirm reef status (DFO 2018).

DFO Fisheries Management (Sustainable Fisheries Framework Unit) has requested advice from the Science Branch assessing the status of these nine suspected reef areas.  The assessment, and advice arising from this Canadian Science Advisory Secretariat (CSAS) Science Response Process (SR), will be used to inform management decisions regarding adaptive management and future monitoring of the sponge reefs in Howe Sound and to respond to stakeholder requests for scientific information on the sponge reefs. No further areas in Howe Sound are expected to be sponge reefs; this project is therefore the last component of science support for the above-mentioned Conservation Initiative.

Objectives

Primary goals of this project are to (1) gather all available ecological and geological data for the nine possible reef areas in Howe Sound; (2) ground-truth seven visual data-deficient areas by surveying them with a Remotely Operated Vehicle (ROV); and (3) determine and summarize reef status and condition for each area.
The specific objectives are:

• For each of the nine areas:
• Map geological signature indicative of glass sponge reefs based on multibeam and backscatter, if present;
• Map the presence of live reef-building glass sponges based on video and still images;
• Determine whether the area is a living sponge reef.
• For each area determined to be a living glass sponge reef:
• Characterize reef condition (sponge cover, habitat categories) using quantitative metrics developed in Dunham et al (2018a) and applied in DFO (2018);
• Create reef summary cards following DFO (2018);
• Provide advice on potential benefits of protection;
• Identify any uncertainties in the data.

Expected Publications

• Science Response

Expected Participation

• Fisheries and Oceans Canada (Fisheries Management, Science)
• Natural Resources Canada
• Underwater Council of BC

References

Chu JWF, Leys SP. 2010. High resolution mapping of community structure in three glass sponge reefs (Porifera, Hexactinellida). Marine Ecology Progress Series 417: 97-113

Conway KJ, Barrie V, Krautter M. 2004. Modern siliceous sponge reefs in a turbid, siliciclastic setting: Fraser River delta, British Columbia, Canada. Neues Jahrbuch fur Geologie und Palaontologie-Monatshefte: 335-350.

Conway KW, Barrie JV, Krautter M. 2005. Geomorphology of unique reefs on the western Canadian shelf: sponge reefs mapped by multibeam bathymetry. Geo-Marine Letters 25: 205-213.

Conway KW, Barrie JV, Hill PR, Austin WC, Picard K (2007) Mapping sensitive benthic habitats in the Strait of Georgia, coastal British Columbia: deep-water sponge and coral reefs. Geol. Surv. Can. 2007-A2: 1-6.

Cook SE, Conway KW, Burd B. 2008. Status of the glass sponge reefs in the Georgia Basin. Marine Environmental Research 66 (Suppl 1): S80–S86.

DFO. 2018. Glass sponge aggregations in Howe Sound: locations, reef status, and ecological significance assessment. DFO Can. Sci. Advis. Sec. Sci. Resp. 2018/032.

DFO. 2019. Strait of Georgia and Howe Sound Glass Sponge Reef Conservation Initiative.

Dunham A., Mossman J, Archer S., Pegg J, Archer E. 2018a. Glass Sponge Reefs in the Strait of Georgia and Howe Sound: Status assessment and ecological monitoring advice. DFO Can. Sci. Advis. Sec. Res. Doc. 2018/010.

Dunham A, Archer SK, Davies S, Burke L, Mossman J, Pegg J. 2018b. Assessing ecological role of deep-water biogenic habitats: Glass sponge reefs in the Salish Sea. Marine Environmental Research 141: 88-99.

Marliave JB, Conway KW, Gibbs DM, Lamb A, Gibbs C. 2009. Biodiversity and rockfish recruitment in sponge gardens and bioherms of southern British Columbia, Canada. Marine Biology 156: 2247-2254.