A review of the role of submarine canyons in deep-ocean exchange with the shelf

Allen, Susan E.; Madron, Xavier Durrieu de

doi:10.5194/os-5-607-2009

Cited by 199 publications

(88 citation statements)

References 109 publications

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“…These modifications of the currents may result in local upwelling, which pumps nutrients to the euphotic zone and thus stimulates primary production (Ryan et al, 2005). Additionally, closedcirculation cells and downwelling may develop over canyons, enhancing the capacity of the canyon to trap particles transported by long-shore currents (Granata et al, 1999;Palanques et al, 2005;Allen and Durrieu de Madron, 2009). When thermohaline stratification of the water column is strong, the flow in the upper mixed layer may decouple from the underlying water levels, which interact with the rims of the canyon.…”

Section: Canyon Effects On Local Circulation and Sedimentationmentioning

confidence: 99%

“…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). These geomorphologic features act as preferential particle-transport routes from the productive coastal zone down continental slopes to the more stable deep seafloor (Allen and Durrieu de Madron, 2009;Puig et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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Submarine canyons are major geomorphic features of continental margins around the world. Several recent multidisciplinary projects focused on the study of canyons have considerably increased our understanding of their ecological role, the goods, and services they provide to human populations, and the impacts that human activities have on their overall ecological condition. Pressures from human activities include fishing, dumping of land-based mine tailings, and oil and gas extraction. Moreover, hydrodynamic processes of canyons enhance the down-canyon transport of litter. The effects of climate change may modify the intensity of currents. This potential hydrographic change is predicted to impact the structure and functioning of canyon communities as well as affect nutrient supply to the deep-ocean ecosystem. This review not only identifies the ecological status of canyons, and current and future issues for canyon conservation, but also highlights the need for a better understanding of anthropogenic impacts on canyon ecosystems and proposes other research required to inform management measures to protect canyon ecosystems.

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Section: Canyon Effects On Local Circulation and Sedimentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2017

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“…Also, the presence of submarine canyons intersecting continental shelves can enhance across-shelf sediment transport, by intercepting the along-shore sediment drift, promoting and intensifying ageostrophic flows, focusing internal waves and tides or channelling density currents (Hickey, 1997;Puig et al, 2004;Martín et al, 2007Martín et al, , 2011Allen and Durrieu de Madron, 2009;Palanques et al, 2011).…”

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confidence: 99%

Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter

et al. 2013

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Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of the mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed for the study of the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms (maximum significant wave heights = 4.1–4.6 m). During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of the CCC in an approximate depth range of 150–350 m. The density of this water mass was lighter than the ambient water in the canyon, indicating that it did not cascade off-shelf and that it merely downwelled into the canyon forced by the strong cyclonic circulation induced over the shelf during the storms and by the subsequent accumulation of seawater along the coast. Suspended sediment load in this turbid intrusion recorded along the southern canyon flank oscillated between 10 and 50 mg L⁻¹, and maximum currents speeds reached values up to 90 cm s⁻¹. A rough estimation of 10⁵ tons of sediment was transported through the canyon along its southern wall during a 3-day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down- to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated with eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200–300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea

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“…Various interactions have been observed with storm-induced downwelling, along-slope ambient currents, tides, and sediment resuspension, and these generally appear to strengthen the cascading of dense water. However, canyons can also act to funnel deep ocean water onto the shelf, as was observed many years ago at the Cape Canyon near Cape Town (Nelson, 1985: see also Allen and Durrieu de Madron, 2009). …”

Section: Topographymentioning

confidence: 91%

“…Estimates of cross-shelf fluxes through canyons are made in Allen and Durrieu de Madron (2009) in this Special Issue. However, very few studies have estimated the cross-shelf transport of tracers.…”

Section: Topographymentioning

confidence: 99%