Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon
10 pages, 8 figures
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Elsevier
2014-06
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Subjects: | Trawling, Man-induced effects, Submarine canyons, Sediment dynamics, Resuspension, Nepheloid layers, Northwestern Mediterranean, |
Online Access: | http://hdl.handle.net/10261/80451 |
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dig-icm-es-10261-804512020-11-26T18:23:19Z Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon Martín, Jacobo Puig, Pere Palanques, Albert Ribó, Marta Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean 10 pages, 8 figures Commercial bottom trawling is one of the anthropogenic activities causing the biggest impact on the seafloor due to its recurrence and global distribution. In particular, trawling has been proposed as a major driver of sediment dynamics at depths below the reach of storm waves, but the issue is at present poorly documented with direct observations. This paper analyses changes in water turbidity in a tributary valley of the La Fonera (=Palamós) submarine canyon, whose flanks are routinely exploited by a local trawling fleet down to depths of 800 m. A string of turbidimeters was deployed at 980 m water depth inside the tributary for two consecutive years, 2010–2011. The second year, an ADCP profiled the currents 80 m above the seafloor. The results illustrate that near-bottom water turbidity at the study site is heavily dominated, both in its magnitude and temporal patterns, by trawling-induced sediment resuspension at the fishing ground. Resuspended sediments are channelised along the tributary in the form of sediment gravity flows, being recorded only during working days and working hours of the trawling fleet. These sediment gravity flows generate turbid plumes that extend to at least 100 m above the bottom, reaching suspended sediment concentrations up to 236 mg l−1 close to the seafloor (5 m above bottom). A few hours after the end of daily trawling activities, water turbidity progressively decreases but resuspended particles remain in suspension for several hours, developing bottom and intermediate nepheloid layers that reach background levels ∼2 mg l−1 before trawling activities resume. The presence of these nepheloid layers was recorded in a CTD+turbidimeter transect conducted across the fishing ground a few hours after the end of a working day. These results highlight that deep bottom trawling can effectively replace natural processes as the main driving force of sediment resuspension on continental slope regions and generate increased near-bottom water turbidity that propagates from fishing grounds to wider and deeper areas via sediment gravity flows and nepheloid layer development We are grateful to the crew and officers of B/O García del Cid (CSIC) and “Lluerna” (Generalitat de Catalunya) and to the participants in the HERMIONE-I & II surveys for their help at sea. This work is funded by the HERMIONE project (Grant agreement 226354) under the European Commission's 7th framework Programme. J. Martín was funded through a JAE DOC contract within the Program «Junta para la Ampliación de Estudios», granted by Consejo Superior de Investigaciones Científicas and co-financed by the European Social Fund. We thank the two anonymous reviewers who helped to improve the submitted manuscript through their constructive comments Peer reviewed 2013-08-01T11:25:35Z 2013-08-01T11:25:35Z 2014-06 artículo http://purl.org/coar/resource_type/c_6501 Deep Sea Research - Part II - Topical Studies in Oceanography 104: 174–183 (2014) 0967-0645 http://hdl.handle.net/10261/80451 10.1016/j.dsr2.2013.05.036 #PLACEHOLDER_PARENT_METADATA_VALUE# info:eu-repo/grantAgreement/EC/FP7/226354 https://doi.org/10.1016/j.dsr2.2013.05.036 open Elsevier |
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Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean |
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Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean Martín, Jacobo Puig, Pere Palanques, Albert Ribó, Marta Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
description |
10 pages, 8 figures |
format |
artículo |
topic_facet |
Trawling Man-induced effects Submarine canyons Sediment dynamics Resuspension Nepheloid layers Northwestern Mediterranean |
author |
Martín, Jacobo Puig, Pere Palanques, Albert Ribó, Marta |
author_facet |
Martín, Jacobo Puig, Pere Palanques, Albert Ribó, Marta |
author_sort |
Martín, Jacobo |
title |
Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
title_short |
Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
title_full |
Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
title_fullStr |
Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
title_full_unstemmed |
Trawling-induced daily sediment resuspension in the flank of a Mediterranean submarine canyon |
title_sort |
trawling-induced daily sediment resuspension in the flank of a mediterranean submarine canyon |
publisher |
Elsevier |
publishDate |
2014-06 |
url |
http://hdl.handle.net/10261/80451 |
work_keys_str_mv |
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1777665936469262336 |