Glass sponge bioherms in Howe Sound: mapping, citizen science and impacts of climate and fishing

Abstract

There are three species of glass sponges (Class Hexactinellida) that are capable of forming reefs (bioherms). Historically, glass sponge bioherms have been discovered along the NW Pacific Coast of Canada through multi-beam sonar surveys. However, twelve bioherms have been discovered in Howe Sound through a novel and inexpensive drop camera system that were missed in previous sonar explorations of the area due to incompatibility of the sonar resolution with the steep, complex bathymetry of the fjord. Of these bioherms, ten are shallower than 50 meters and accessible by SCUBA for hands-on research, six of them amenable to diving on compressed air (30-40m). These bioherms provide a unique opportunity for citizen science-driven/-partnered research. Various citizen science partnerships and projects are currently underway, such as one designed to observe long-term benthic temperatures within bioherms. This project will endeavour to further our understanding of the effects of El Niño Southern Oscillation (ENSO) events on glass sponge growth and decay cycles. Cloud sponge mortality has been associated with the 2009/2010 and 2015/2016 El Niños. Another project has proven ability for tissue repair during La Niña events. The principal citizen science initiative of Howe Sound bioherm exploration also provided direct evidence of damage by prawn trapping. These newly discovered sites in Howe Sound are providing unparalleled opportunities for leading-edge glass sponge and bioherm research that can involve the community as a partner. Citizen science participation increases environmental awareness and understanding which will increase public stewardship to this globally unique ecosystem