title: Effects of submarine power transmission cables on a glass sponge reef and associated megafaunal community.
abstract: We examined the effects of submarine power transmission cable installation and operation on glass sponge reef condition and associated megafauna. Video and still imagery were collected using a Remotely Operated Vehicle twice a year for 4 years following cable installation. The effects of cables on glass sponges were assessed by comparing sponge cover along fixed transects and at marked index sites. Megafauna counts along transects were used to explore the effects on associated community. We found no evidence of cable movement across the sponge reef surface. Live sponge cover was found to be consistently lower along cable transects and at cable index sites compared to controls. Live sponge cover was the lowest (55 ± 1.1% decrease) at cable index sites 1.5 years after installation and recovered to 85 ± 30.6% of the original size over the following 2 years. Our data suggest 100% glass sponge mortality along the direct cable footprint and 15% mortality in the surrounding 1.5 m corridor 3.5 years after cable installation. Growth rate of a new glass sponge was 1 and 3 cm/year in first and second year, respectively, and appeared to be seasonal. We observed a diverse megafaunal community with representatives from 7 phyla and 14 classes. Total megafauna, spot prawn, and other Arthropoda abundances were slightly lower along cable transects although the effect of cable presence was not statistically significant. The following measures could be taken to reduce the amount of damage to glass sponge reefs and associated fauna: routing the cable around reefs, whenever possible, minimizing cable movement across the surface of the reef at installation and routine operation, and assessing potential damage to glass sponges prior to decommissioning.
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada; Fisheries and Aquaculture Department, Vancouver Island University, 900 Fifth Street, Nanaimo, BC V9R 5S5, Canada. Electronic address: Anya.Dunham@dfo-mpo.gc.ca.
authors.forename: A
authors.initials: A
authors.lastname: Dunham
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada.
authors.forename: J R
authors.initials: JR
authors.lastname: Pegg
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada.
authors.forename: W
authors.initials: W
authors.lastname: Carolsfeld
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Davies
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada.
authors.forename: I
authors.initials: I
authors.lastname: Murfitt
authors.affiliation: Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC V9T 6N7, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Boutillier
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D011211:Electric Power Supplies; D005399:Fishes; D007448:Invertebrates / Q000502:physiology*; D011156:Population Density; D011161:Porifera / Q000254:growth & development / Q000502:physiology*; D012621:Seasons
keywords: Aphrocallistes vastus; Glass sponge reef; Heterochone calyx; Submarine power cable; Underwater visual survey