Continental Slope and Submarine Canyons: Benthic Biodiversity and Human Impacts

Leo, Fabio C. De; Bernardino, Ângelo F.; Sumida, Paulo Yukio Gomes

doi:10.1007/978-3-030-53222-2_3

Cited by 12 publications

(7 citation statements)

References 119 publications

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“…In general, the distribution of deep-sea bottom fauna follows the dynamics of water masses, productivity at the surface of the ocean, and climatic zonation ( Vinogradova, 1979 ; Zezina, 1997 ; Carney, 2005 ; McClain & Hardy, 2010 ; McClain & Schlacher, 2015 ). However, in some areas the benthic distribution patterns have shown to be more related to horizontal (latitudinal), rather than vertical limits (water column) ( De Leo, Bernardino & Sumida, 2020 ; Summers & Watling, 2021 ), and our results appear support those regional processes.…”

Section: Discussionsupporting

confidence: 77%

“…It contains an extensive deep-sea territory with a wide variety of seafloor features distributed along latitudinal and productivity gradients. One of the largest and most notorious geomorphological features is the Vitoria-Trindade Ridge (VTR; 21°S), a seamount chain adjacent to the BCM that naturally delimits the tropical and subtropical portions of the BCM and the contiguous abyssal plains ( De Leo, Bernardino & Sumida, 2020 ) ( Fig. 1 ).…”

Section: Methodsmentioning

confidence: 99%

“…The Brazilian continental margin (BCM) extends along the Tropical and Subtropical Atlantic Ocean ( Spalding et al, 2007 ), and belongs to a tectonically passive-type margin with a typically wide (>100 km) continental shelf. The BCM is within the Brazilian Exclusive Economic Zone (EEZ) that comprises a total area of 3.6 million km 2 , ranking 11th in terms of size worldwide ( Sumida, De Leo & Bernardino, 2020 ; De Leo, Bernardino & Sumida, 2020 ). It contains an extensive deep-sea territory, with a broad variety of seafloor geomorphological features, which are distributed along wide latitudinal and productivity gradients.…”

Section: Introductionmentioning

confidence: 99%

“…It contains an extensive deep-sea territory, with a broad variety of seafloor geomorphological features, which are distributed along wide latitudinal and productivity gradients. The broad range and diversity of seafloor features hosts a great diversity of ecosystems and associated species ( De Leo, Bernardino & Sumida, 2020 ; Magris et al, 2020 ). Much of these features have been poorly sampled at depths below 200 m, and the Southeast margin has been more sampled and studied due to the interest of the offshore oil and gas industry ( Sumida & Pires-Vanin, 1997 ; Netto, Gallucci & Fonseca, 2005 ; Bernardino, Berenguer & Ribeiro-Ferreira, 2016 ; Almada & Bernardino, 2017 ; Fujikura et al, 2017 ; Bernardino et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

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Benthic biogeographic patterns on the deep Brazilian margin

Yepes-Gaurisas¹,

Bernardino²

2023

PeerJ

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The Brazilian continental margin (BCM) extends from the Tropical to the Subtropical Atlantic Ocean, with much of its seafloor within deep waters, supporting rich geomorphological features and under wide productivity gradients. Deep-sea biogeographic boundaries on the BCM have been limited to studies that used water mass and salinity properties of deep-water masses, partly as a result of historical under sampling and a lack of consolidation of available biological and ecological datasets. The aim of this study was to consolidate benthic assemblage datasets and test current oceanographic biogeographical deep-sea boundaries (200–5,000 m) using available faunal distributions. We retrieved over 4,000 benthic data records from open-access databases and used cluster analysis to examine assemblage distributions against the deep-sea biogeographical classification scheme from Watling et al. (2013). Starting from the assumption that vertical and horizontal distribution patterns can vary regionally, we test other schemes incorporating latitudinal and water masses stratification within the Brazilian margin. As expected, the classification scheme based on benthic biodiversity is in overall agreement with the general boundaries proposed by Watling et al. (2013). However, our analysis allowed much refinement in the former boundaries, and here we propose the use of two biogeographic realms, two provinces and seven bathyal ecoregions (200–3,500 m), and three abyssal provinces (>3,500 m) along the BCM. The main driver for these units seems to be latitudinal gradients as well as water mass characteristics such as temperature. Our study provides a significant improvement of benthic biogeographic ranges along the Brazilian continental margin allowing a more detailed recognition of its biodiversity and ecological value, and also supports the needed spatial management for industrial activities occurring in its deep waters.

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Section: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Benthic biogeographic patterns on the deep Brazilian margin

Yepes-Gaurisas¹,

Bernardino²

2023

PeerJ

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“…Continental slope incised submarine canyons are key conduits in connecting shallow inner continental margins with the deep seafloor, especially during sea‐level lowstands (Normark, 1970; Posamentier et al ., 1991). Recent research on modern submarine canyons has further demonstrated that, under high sea‐level conditions, these geomorphic features also play a fundamental role in delivering substantial amounts of sediment, nutrients and pollutants – including litter, mainly made of plastics – to the deep, thus affecting the functioning and environmental state of deep water ecosystems (Fildani, 2017; De Leo & Puig, 2018; Fildani et al ., 2018; Hage et al ., 2020; Kane & Fildani, 2021; Zhong & Peng, 2021). Submarine canyons, especially at their heads and upper courses, are also known for being highly productive sites hosting a rich biodiversity (McClain & Barry, 2010; Lacono et al ., 2012; Robert et al ., 2014; Lastras et al ., 2016; De Leo et al ., 2020; Ríos et al ., 2022).…”

Section: Introductionmentioning

confidence: 99%

Bedform evolution along a submarine canyon in the South China Sea: New insights from an autonomous underwater vehicle survey

Sun,

Wang,

Canals

et al. 2023

Sedimentology

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Traditional mapping of bedforms in submarine canyons relied on vessel‐mounted and towed sensors, but their fine‐scale geomorphology and shallow structure requires higher resolution datasets. This study utilizes a high‐resolution dataset obtained from an autonomous underwater vehicle, combined with seismic reflection profiles and sediment cores, to analyse bedform sets within a 25.6 km long submarine canyon (canyon C14) in the northern South China Sea. A train of crescent‐shaped axial steps, indicative of cyclic steps formed by supercritical turbidity currents, is imaged along the canyon. Axial steps in the upper course show erosional truncations and sub‐horizontal reflectors on the lee and stoss sides, respectively, pointing to erosional–depositional cyclic steps formed by confined flows with high erosional capacity. This is facilitated by canyon narrowness and steeper axial gradient. After a transition segment, the lower course widens, with a gentler axial gradient, resulting in increased asymmetry and wavelength of axial steps. Backset bed deposits on the stoss sides of these steps indicate depositional cyclic steps with higher aggradation. Sediment filling, almost padding each cyclic step associated scour suggests the reworking of previously formed bedforms by gravity flows fed by destabilization processes on the canyon sidewalls and upstream lee faces and, possibly, by shelf‐edge and uppermost slope spillover into the canyon. At the lowermost course, cyclic steps transition to a furrow field, likely associated with flow velocity reduction facilitated by canyon floor widening and a further decrease in slope gradient. Flow braiding and re‐convergence, related to the erosion of fine‐grained deposits within the canyon floor, should have played a role to produce furrows under supercritical conditions. This work enhances our understanding of the detailed morphology and shallow relief configuration of bedforms in deep‐water submarine canyons, providing insights into their causative processes and evolution.

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