Organic matter contents and degradation in a highly trawled area during fresh particle inputs (Gulf of Castellammare, southwestern Mediterranean)
Paradis, Sarah (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Pusceddu, Antonio (Università degli Studi di Cagliari. Dipartimento di Scienze della Vita e dell'Ambiente (Italy))
Masqué Barri, Pere (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Puig i Alenyà, Pere (Institut de Ciències del Mar)
Moccia, Davide (Università degli Studi di Cagliari. Dipartimento di Scienze della Vita e dell'Ambiente (Italy))
Russo, Tommaso (Università degli Studi di Roma Tor Vergata. Dipartimento di Biologia. Laboratorio di Ecologia Sperimentale e Acquacoltura (Italy))
Iacono, Claudio Lo (University of Southampton Waterfront Campus. National Oceanography Centre (UK))

Fecha:	2019
Resumen:	Bottom trawling in the deep sea is one of the main drivers of sediment resuspension, eroding the seafloor and altering the content and composition of sedimentary organic matter (OM). The physical and biogeochemical impacts of bottom trawling were studied on the continental slope of the Gulf of Castellammare, Sicily (southwestern Mediterranean), through the analysis of two triplicate sediment cores collected at trawled and untrawled sites (<span classCombining double low line"inline-formula">ĝ'1/4550</span> m water depth) during the summer of 2016. Geochemical and sedimentological parameters (excess <span classCombining double low line"inline-formula">210Pb</span>, excess <span classCombining double low line"inline-formula">234Th</span>, <span classCombining double low line"inline-formula">137Cs</span>, dry bulk density, and grain size), elemental (organic carbon and nitrogen) and biochemical composition of sedimentary OM (proteins, carbohydrates, lipids), as well as its freshness (phytopigments) and degradation rates were determined in both coring locations. The untrawled site had a sedimentation rate of 0. 15 cm yr<span classCombining double low line"inline-formula">-1</span> and presented a 6 cm thick surface mixed layer that contained siltier sediment with low excess <span classCombining double low line"inline-formula">210Pb</span> concentrations, possibly resulting from the resuspension, posterior advection, and eventual deposition of coarser and older sediment from adjacent trawling grounds. In contrast, the trawled site was eroded and presented compacted century-old sediment highly depleted in OM components, which were between 20 % and 60 % lower than those in the untrawled site. However, the upper 2 cm of the trawled site consisted of recently accumulated sediments enriched in excess <span classCombining double low line"inline-formula">234Th</span>, excess <span classCombining double low line"inline-formula">210Pb</span>, and phytopigments, while OM contents were similar to those from the untrawled core. This fresh sediment supported protein turnover rates of 0. 025 d<span classCombining double low line"inline-formula">-1</span>, which doubled those quantified in surface sediments of the untrawled site. The enhancement of remineralization rates in surface sediment of the trawled site was associated with the arrival of fresh particles on a chronically trawled deep-sea region that is generally deprived of OM. We conclude that the detrimental effects of bottom trawling can be temporarily and partially abated by the arrival of fresh and nutritionally rich OM, which stimulate the response of benthic communities. However, these ephemeral deposits are likely to be swiftly eroded due to the high trawling frequency over fishing grounds, highlighting the importance of establishing science-based management strategies to mitigate the impacts of bottom trawling.
Ayudas:	European Commission 312762 Ministerio de Economía y Competitividad CTM2015-65142-R Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-863 Agència de Gestió d'Ajuts Universitaris i de Recerca 2017/SGR-1588 Ministerio de Economía y Competitividad MDM2015-0552 Ministerio de Educación, Cultura y Deporte FPU14/07039
Nota:	Unidad de excelencia María de Maeztu MdM-2015-0552
Derechos:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Lengua:	Anglès
Documento:	Article ; recerca ; Versió publicada
Publicado en:	Biogeosciences, Vol. 16, Issue 21 (November 2019) , p. 4307-4320, ISSN 1726-4189

DOI: 10.5194/bg-16-4307-2019

14 p, 4.3 MB

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