First description of a glass sponge reef soundscape reveals fish calls and elevated sound pressure levels

Structured biogenic habitats are biodiversity hotspots that host a wide range of soniferous species. Yet in deep-water systems, their soundscapes are largely undescribed. In September of 2016 we deployed 3 underwater acoustic recorders for approximately 4 d in and around a glass sponge reef in the Outer Gulf Islands sponge reef fishing closure, British Columbia, Canada. The 2 recordings from the reef (within and at the margin of the reef footprint) were significantly louder in the mid- and high-frequency bands (100 to 1000 Hz and 1 to 10 kHz, respectively) than the recordings made in soft-bottom habitat away from the reef. These frequency bands are known to correlate with aspects of the biological community as well as benthic cover in shallow-water systems; visual surveys conducted in the area confirmed the presence of several known soniferous species. More fish sounds were recorded on the reef compared to the off-reef site. Our results suggest that this glass sponge reef has a distinct soundscape and that future work linking aspects of the soundscape to the ecology of the ecosystem are warranted.