Nearly a decade of deep-sea monitoring in Barkley Canyon, NE Pacific, using the NEPTUNE cabled observatory

Abstract

Cabled observatories provide a permanent presence in the ocean, enabling discovery and tracking of previously unseen faunal behaviour and long-term changes in biodiversity and ecosystem function. Ocean Networks Canada operates large seafloor cabled observatory networks in the NE Pacific and in the Arctic. The seafloor network of 850+ km of backbone cables connects > 50 instrumented sites (>400 oceanographic instruments, >5,000 sensors), in habitats ranging from temperate coastal fjords and rocky reefs, ice-covered Arctic bays, to deep-sea canyons, cold seeps, abyssal plains and hydrothermal vents. Here we showcase nearly 10 years of deep-sea monitoring in Barkley Canyon, off the coast of British Columbia, and various research projects investigating a range of topics including benthic biodiversity and ecosystem function, bentho-pelagic coupling, fate of organic falls, sediment and organic matter transport and seasonal deep zooplankton ontogenetic migration. Approaching almost a decade since the NEPTUNE observatory came online in 2009, we were able to identify the main processes driving benthic biodiversity and ecosystem function, such as sea surface productivity and carbon flux, atmospheric and astronomic forcing, and the effects of the NE Pacific oxygen minimum zone. We also describe recently deployed and upcoming experiments designed to: 1) identify natural and anthropogenic sediment transport processes and its effects on the benthic biota; 2) to monitor seasonal and internal fluctuations in abundance and size-structure of commercially exploited species (e.g., rockfish Sebastolobus alascanus and S. altivelis, blackcod Anoplopoma fimbria, tanner crab, Chionoecetes tanneri) using video imagery and passive and active acoustics