5 year-long monitoring of Barkley Canyon cold-seeps with the internet operated deep-sea crawler "Wally"

Despite the technological advances of the last decades (e.g. ROVs, AUVs, cabledobservatories), our knowledge of most deep-sea environments is still stronglylimited by spatio-temporal sampling and observational capabilities. The novelInternet Operated Deep-Sea Crawler technology can provide high-frequency,multi-sensor data, during long-term deployments, 24/7 communication withresearchers and broader spatial coverage (i.e. mobile platform) than fixedinstrument installations. The crawler “Wally” is deployed at the Barkley Canyonmethane hydrates site (NE Pacific, Canada; ~890 m depth) and connected to theOcean Networks Canada NEPTUNE cabled observatory network (ONC; www.oceannetworks.ca). Here we present the environmental and biological datasetsobtained from Wally instruments and cameras, during the first deployment phase(September 2010 to January 2015), as well as new features and preliminaryresults obtained since it was re-deployed (May 2016 – present). In addition to dataprovided by the standard payload of the crawler (i.e. ADCP, CTD, methane sensor,turbidity sensor and fluorometer), the hydrates community was video-monitored atdifferent frequencies and timespans. Photomosaics were generated at two distinctlocations, in order to map chemosynthetic bacterial mats and vesicomyid clamcolonies covering the ~2-3 m high hydrate mounds, and document their temporaldynamics. The crawler followed the development of a deep-sea shell taphonomicexperiment aiming to quantify biogenic carbon fluxes at the hydrates environment.The composition and diel activity patterns of the hydrates megafaunal communitywere studied with the use of linear video-transects conducted from February 2013 toApril 2014. Since the summer of 2016, video-frames recorded at different locationsof the site are analyzed for a biodiversity study and photomosaicing of the hydratemounds continues, with 3D modelling of the mound structures also available as anew feature of the crawler deployed in May 2016. All data are archived in real-timeand can be accessed online on the Ocean Networks Canada database. As deep-seacrawler technology and similar mobile, benthic platform technologies progresstowards full operational autonomy, they will provide an even greater capacity forfuture monitoring and understanding of dynamic, extreme environments such asmethane hydrate fields.