Terms of Reference

Glass sponge reefs in the Strait of Georgia and Howe Sound: status assessment and monitoring advice

Regional Peer Review Process – Pacific Region

March 1-2, 2017
Nanaimo, British Columbia

Chairperson: Mary Thiess

Context

Glass sponge reefs are unique habitats found along the Pacific coast of Canada and the United States. They are built by dictyonine glass sponges with spicules of nearly pure glass that form reefs through the attachment of larvae to exposed skeletons of dead sponges and by trapping sediments entrained in bottom currents. The reefs gradually grow to reach heights of up to 21 meters and widths of up to several kilometers. The bulk of each reef consists of dead sponges buried by sediments, with only the most recent generation of sponges growing one to two meters above the ocean floor.

Glass sponge reefs have intrinsic, ecological, and economic value. They provide a link between benthic and pelagic environments, play an important role in carbon and nitrogen processing, and act as a silica sink. While a full understanding of their ecological role is yet to be realized, diverse communities of invertebrates and fish, including those of economic importance, have been documented in association with the reefs (Cook et al. 2008, Marliave et al. 2009, Chu and Leys 2010).

Over the past 14 years, nine glass sponge reef complexes have been mapped by the Canadian Hydrographic Service in the Strait of Georgia and Howe Sound using remote sensing, multibeam sonars (Conway et al. 2004; Conway et al. 2005; Conway et al. 2007; Kim Conway, Natural Resources Canada, Sidney, BC, pers. comm.). However, remote sensing techniques cannot differentiate between live, dead, and dead and buried patches of glass sponges within a reef; therefore, while these techniques assist in locating and delineating glass sponge reef structure, they cannot provide information on reef status or health. In the past, some of the reefs were surveyed for live glass sponge abundance and distribution using Remotely Operated Vehicles (ROVs) (Cook et al. 2008; Chu and Leys 2010), while others remained unassessed. Furthermore, no standard quantitative metrics for sponge health or sponge reef status have been developed to date.

In 2012 and 2013, the nine glass sponge reefs in the Strait of Georgia and Howe Sound—previously delineated with remote sensing techniques—were surveyed by Fisheries and Oceans Canada (DFO) Science using an ROV and a standardized survey design to document live glass sponges and megafaunal communities associated with them. These surveys confirmed the presence of live reef-building glass sponges in all nine reefs.  In 2014, DFO requested that fishers using bottom-contact gear (prawn trap, crab trap, shrimp trawl, groundfish trawl and hook-and-line) voluntarily avoid these nine glass sponge reef areas while DFO consulted on formal protection measures.  After reviewing important input from the consultation process with First Nations, commercial and recreational fishers and conservation organizations, DFO proceeded with formal fishery closures to protect the nine glass sponge reef complexes in the Strait of Georgia and Howe Sound, effective June 12, 2015. Beginning April 1, 2016, the closures also apply to First Nations Food, Social, and Ceremonial fisheries.

The protection of sponge reefs is a key component to a number of international commitments made by Canada through the United Nations Convention on Biological Diversity and the United Nations Food and Agriculture Organization (FAO) Code of Conduct for Responsible Fisheries. During the consultation process, multiple stakeholders inquired about DFO’s plans to monitor effectiveness of glass sponge reef closures. DFO Fisheries Management has requested Science Branch to provide an evaluation of the current health status of the nine reef complexes, along with science advice for how reefs could be monitored on an ongoing basis. Therefore, the primary goals of this work are to: (1) assess the status of the nine glass sponge reefs in the Strait of Georgia and Howe Sound prior to bottom fishery closures being put in place (monitoring baseline); and (2) provide recommendations for future monitoring initiatives. This work focuses on the nine glass sponge reef complexes included in the current fishery closure process; other sponge reefs that may be found in the area and sponge formations (such as sponge gardens) are out of scope.

The assessment and advice arising from this Canadian Science Advisory Secretariat (CSAS) Regional Peer Review (RPR) will be used to inform management decisions regarding adaptive management and future monitoring of the sponge reefs in the Strait of Georgia and Howe Sound and to respond to stakeholder requests for scientific information on the sponge reefs. It will support the Department's implementation of the Policy to Manage the Impacts of Fishing on Sensitive Benthic Areas and the Ecological Risk Assessment Framework for Cold-water Coral and Sponge Dominated Communities in the Pacific Region.

Objectives

The following working paper will be reviewed and provide the basis for discussion and advice:

• Dunham, A., Mossman, J., Archer., S, Pegg, J., Davies, S. Glass sponge reefs in the Strait of Georgia and Howe Sound: status assessment and monitoring advice. CSAP Working Paper 2014SFF02.

The objectives are to:

1. Describe and map the presence of live reef-building glass sponges in nine sponge reefs complexes in the Strait of Georgia and Howe Sound protected by DFO’s bottom-contact fishery closure initiative.
2. Characterize the range of environmental conditions encountered by glass sponge reefs in the Strait of Georgia and Howe Sound.
3. Characterize megafaunal communities associated with glass sponge reefs.
4. Develop glass sponge reef condition and/or recovery potential metric(s) to enable objective quantitative comparisons over time and space.
5. Characterize condition of each of the nine reef complexes prior to commencement of bottom-contact fishery closures for use as the monitoring baseline.
6. Explore correlation between reef condition and associated megafaunal community structure.
7. Provide recommendations for monitoring strategy, methods, and protocol development.
8. Examine and identify uncertainties in the data and methods.
9. Provide recommendations on future research needs.

Expected Publications

• Science Advisory Report
• Proceedings
• Research Document

Expected Participation

• DFO: Science, Fisheries and Aquaculture Management, Oceans, Fisheries Protection Program
• First Nations
• Province of BC
• Academia
• Fishing industry (recreational and commercial: prawn trap, crab trap, shrimp trawl, groundfish trawl, and hook-and-line)
• Environmental non-government organizations: Canadian Parks and Wilderness Society (CPAWS), Marine Life Sanctuaries Society, Vancouver Aquarium, Sunshine Coast Conservation Society.

References

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

Conway, K.W., Barrie, J.V., Hill, P.R., Austin, W.C., Picard, K., 2007. Mapping sensitive benthic habitats in the Strait of Georgia, coastal British Columbia: deep-water sponge and coral reefs. Geological Survey of Canada. Current Research. 2007-A2. 6pp.

Conway, K.W., Barrie, J.V., Krautter, M., 2004. Modern siliceous sponge reefs in a turbid  siliciclastic setting: Fraser River delta, British Columbia, Canada. Neues Jahrbuch für  Geologie und Paläontologie. 2004: 335-350.

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

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

Marliave J.B., Conway, K.W., Gibbs, D.M., Lamb, A., Gibbs, C. (2009) Biodiversity and rockfish recruitment in sponge gardens and bioherms of southern British Columbia, Canada. Marine Biology. 156, 2247-2254.