Surface-sediment bioturbation quantified with cameras on the NEPTUNE Canada cabled observatory

The mixing of deep-sea sediments by benthic megafauna is an important ecological service that influences biogeochemical processes. Quantifying the contribution of individual species to bioturbation and their responses to environmental variations requires experimental manipulation or direct observation, both of which are logistically challenging in the deep sea. Emerging cabled seafloor observatories now permit real-time data transfer to shore and interactive sampling, providing a new tool for long-term studies of the benthos at high temporal resolutions. We report on the development of a methodological approach to study surficial bioturbation by megafauna in a submarine canyon by using video cameras remotely operated over the internet, through the NEPTUNE Canada observatory. Observation protocols and image analysis techniques were developed to quantify organism size, locomotion and appearance rates for 2 flatfishes (Dover sole Microstomus pacificus and Pacific halibut Hippoglossus stenolepis) and the fragile pink sea urchin Allocentrotus fragilis. Application of a Bayesian model to extrapolate megafaunal locomotion patterns and appearance rates yielded sediment-surface reworking rates on the order of 26.0 to 35.1 cm(2) yr(-1). Future observations can be directly incorporated into the model to improve accuracy. We propose that this combined observation and Bayesian modeling approach could become a useful component of a long-term program for monitoring ecological processes on the seafloor.