Data collection
AUV imagery was collected by the AUV Sirius , operated by the University of Sydney’s Australian Centre for Field Robotics as part of the Australian government national IMOS monitoring program. The AUV navigates pre-determined transects, with onboard sensors allowing the AUV to maintain a relatively constant altitude of ~ 2m above the seafloor. This results in a predictably stable image footprint of approximately 1.2 X 1.6 m, with imagery captured at a resolution of ~1 mm/pixel.
Repeated AUV transects were conducted across the study region between 2011 and 2016 (Fig. 1). All sites were surveyed in 2011, 2013 and 2016. The Governor Island NTR was also surveyed in 2014.