Biophysical Factors Affecting the Distribution of Demersal Fish around the Head of a Submarine Canyon Off the Bonney Coast, South Australia

Abstract

We sampled the demersal fish community of the Bonney Canyon, South Australia at depths (100–1,500 m) and locations that are poorly known. Seventy-eight species of demersal fish were obtained from 12 depth-stratified trawls along, and to either side, of the central canyon axis. Distributional patterns in species richness and biomass were highly correlated. Three fish assemblage groupings, characterised by small suites of species with narrow depth distributions, were identified on the shelf, upper slope and mid slope. The assemblage groupings were largely explained by depth (ρw = 0.78). Compared to the depth gradient, canyon-related effects are weak or occur at spatial or temporal scales not sampled in this study. A conceptual physical model displayed features consistent with the depth zonational patterns in fish, and also indicated that canyon upwelling can occur. The depth zonation of the fish assemblage was associated with the depth distribution of water masses in the area. Notably, the mid-slope community (1,000 m) coincided with a layer of Antarctic Intermediate Water, the upper slope community (500 m) resided within the core of the Flinders Current, and the shelf community was located in a well-mixed layer of surface water (<450 m depth).

SMART: A Spatially Explicit Bio-Economic Model for Assessing and Managing Demersal Fisheries, with an Application to Italian Trawlers in the Strait of Sicily

“…This assumption is largely supported in literature [11], [12], [37], [38]. A digital bathymetry grid at 1 min resolution was obtained using the Geodas Grid Translator of the National Geophysical Data Center (NOAA – available online at: www.ngdc.noaa.gov/mgg/global/global.html).…”

Cetacean diversity of the continental shelf and slope off southern australia

“…The 100‐m isobath represents a transition from the gently sloping inner shelf to the more steeply sloping outer shelf. the shelf break at 200 m marks a transition to the steeper upper slope, and the 1,000 m isobath represents an ecological boundary because it coincides with a layer of Antarctic Intermediate Water below the Flinders Current (Currie et al ). We compared depth, depth range, and slope differences between groups using Kruskal‐Wallis tests, and Mann‐Whitney U tests for pairwise comparisons in R™ v3 (R Core Development Team, Vienna, Austria).…”

Classification of submarine canyons of the Australian continental margin

“…5g), the Flinders Current flows westward along the upper continental slope and promotes upwelling, particularly within the topographically complex canyons in the Murray group such as Du Couedic Canyon described above (Middleton and Cirano, 2002;Kampf, 2006;Middleton and Bye, 2007;Kampf, 2010;Currie et al, 2012). This deep canyon upwelling from depths of~250 m helps to form a large sub-surface nutrient pool known as the Kangaroo Island pool (Middleton and Bye, 2007;Kampf, 2010).…”

“…Canyon-specific studies of local patterns in benthic biodiversity (e.g. Schlacher et al, 2007;Currie et al, 2012;Currie and Sorokin, 2014) and of canyon oceanography (e.g. Perth Canyon; S. Rennie et al, 2009) have contributed to an improved understanding of canyons as sites of enhanced productivity.…”