Classification of submarine canyons of the Australian continental margin

Abstract

Submarine canyons influence oceanographic processes, sediment transport, productivity and benthic biodiversity from the continental shelf to the slope and beyond. However, not all canyons perform the same function. The relative influence of an individual canyon on these processes will, in part, be determined by its form, shape and position on the continental margin. Here we present an analysis of canyon geomorphic metrics using an updated national dataset of 713 submarine canyons surrounding mainland Australia. These metrics (attributes) for each canyon are used to classify them into canyon types across a hierarchy of physical characteristics separately for shelf-incising (n = 95) and slope-confined (blind; n = 618) canyons. We find that the canyon metrics describe a wide variety of canyon form and complexity that is consistent with a population of canyons that has evolved at different rates around the Australian margin since the break-up of Gondwana. The large number of slopeconfined canyons is interpreted to reflect dominance of slope mass-wasting processes over erosive turbidity flows from fluvial and shelf sources on an arid continent. The distribution of submarine canyons around the Australian margin is not regular, with clusters occurring in the east, southeast, west and southwest where the margin is steepest. The classification result provides a quantitative framework for describing canyon heterogeneity for application in studies of geological controls on individual canyons, canyon oceanography and canyon biodiversity.Crown

Continental‐scale hotspots of pelagic fish abundance inferred from commercial catch records

“…Hotspot probability was derived as the frequency with which each grid cell was selected as a hotspot across n = 100 bootstrap iterations, with darker tones denoting higher values. Submarine canyons (Huang et al, ) are overlaid in black…”

Ecological Role of Submarine Canyons and Need for Canyon Conservation: A Review

“…Most submarine canyons are located within (EEZs) (Huang et al, 2014), which gives individual nation states the authority to control all extractive activities in their area (e.g., fisheries, oil and gas), thereby these states potentially offer protection to canyons through conservation and management measures such as Marine Protected Areas (MPAs) or fisheries management tools such as spatial/temporal closures of areas or gear restrictions. However, international agreements concerning the rights of free navigation must also be acknowledged in the development of management measures that include such area-based protection regimes.…”

“…Recent novel technological developments including underwater acoustic mapping, imaging, and sampling technologies, and long-term/permanent moored or benthic observatories, have greatly contributed to our understanding of the diverse and complex hydrodynamics (Xu, 2011) and geomorphology of canyons over the last two decades (Robert et al, 2014;Quattrini et al, 2015), allowing the spatiotemporal tracking of oceanographic processes and the associated biological responses, with an integration level that grows every day (Aguzzi et al, 2012;Matabos et al, 2014). As a result of prospective surveys, we know that submarine canyons are major geomorphic features of continental margins, with more than 9000 large canyons covering 11.2% of continental slopes globally , with an estimated accumulated axis length of over 25,000 km (Huang et al, 2014). Canyons are characterized by steep and complex topography (Shepard and Dill, 1966;Lastras et al, 2007;Harris and Whiteway, 2011) that influences current patterns (Shepard et al, 1979;Xu, 2011) and provides a heterogeneous set of habitats, from rocky walls and outcrops to soft sediment (De Leo et al, 2014).…”

Remotely sensed spatial and temporal variability of the Leeuwin Current using MODIS data

“…As the Leeuwin Current is a warm surface current, it has a warmer SST signature compared with water masses on either side, the inshore Huang, Nichol, Harris, and Caley (2014). coastal waters and the offshore subtropical waters.…”