Distribution of seafloor litter and its interaction with benthic organisms in deep waters of the Ligurian Sea (Northwestern Mediterranean)

Type Article
Date 2021-09
Language English
Author(s) Angiolillo Michela1, Gerigny Olivia2, Valente Tommaso1, 3, Fabri Marie-ClaireORCID2, Tambute Eric4, Rouanet Elodie5, Claro Francoise6, Tunesi Leonardo1, Vissio Anne7, Daniel Boris8, Galgani FrancoisORCID2
Affiliation(s) 1 : Istituto Superiore per la Protezione e Ricerca Ambientale (ISPRA), Via Vitaliano Brancati, 60, 00144 Rome, Italy
2 : Institut Français de Recherche pour l'Exploitation de la MER (Ifremer), Centre Méditerranée, Z.P. de Brégaillon, 83507, La Seyne-sur-Mer and Bastia, France
3 : Sapienza University of Rome, Department of Environmental Biology, Piazzale Aldo Moro, 5, 00185 Rome, Italy
4 : Centre Scientifique de Monaco, Avenue Saint Martin, 98000 Monaco, Principality of Monaco
5 : GIS Posidonie, Aix-Marseille University, OSU Pytheas, campus universitaire de Luminy, case 901, 13288 Marseille, cedex 09, France
6 : Muséum National d'Histoire Naturelle-UMS PATRINAT, CP41, 57 rue Cuvier, 75231 Paris, France
7 : Secrétaire exécutif RAMOGE, Av. de l'Annonciade, 98000 Monaco, Principality of Monaco
8 : Agence française pour la biodiversité, rue de la République 26, Marseille, France
Source Science Of The Total Environment (0048-9697) (Elsevier BV), 2021-09 , Vol. 788 , P. 147745 (20p.)
DOI 10.1016/j.scitotenv.2021.147745
WOS© Times Cited 13
Keyword(s) Canyon, Seamount, Litter hotspot, ROV-imaging, Fishing impact, Microplastic

The Mediterranean Sea is one of the most polluted marine basins and currently serves as a hotspot for marine litter. The seafloor represents the ultimate sink for most litter worldwide. Nevertheless, the knowledge about litter distribution and its interactions with benthic organisms in deep water is poorly understood. In 2018, we investigated spatial patterns of macro- and micro-litter distribution, and their effects on benthic communities in the Ligurian Sea. An oceanographic survey was carried out with a remotely operated vehicle and a multibeam echosounder on seven seamounts and canyons, at depths ranging from 350 to 2200 m. High litter accumulations were discovered at the mouth of the Monaco canyon, where estimated densities of up to 3.8 × 104 items km-2 were found at 2200 m depth. The highest abundance of urban litter items was found on the soft substrate, at the bottom of the deeper parts of the submarine canyons, which seem to act as conduits carrying litter from the shelf towards deeper areas. In contrast, fishing-related items were most abundant in the upper layer of the seamounts (300–600 m depths). Furthermore, more than 10% of the observed deep gorgonian colonies were entangled by lost longlines, indicating the detrimental effects of this fishing gear on benthic habitats. The discovery of new litter hotspots and the evaluation of how deep-sea species interact with litter contribute to increasing the knowledge about litter distribution and its effects on the deep ecosystem of the Mediterranean basin. All the observations recorded in this study showed substantial and irreversible changes in the deep and remote areas of marine environments, and these changes were found to be caused by humans. Our findings further stress the need for urgent and specific measures for the management of deep-sea pollution and the reduction of litter inputs in the environment.

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Angiolillo Michela, Gerigny Olivia, Valente Tommaso, Fabri Marie-Claire, Tambute Eric, Rouanet Elodie, Claro Francoise, Tunesi Leonardo, Vissio Anne, Daniel Boris, Galgani Francois (2021). Distribution of seafloor litter and its interaction with benthic organisms in deep waters of the Ligurian Sea (Northwestern Mediterranean). Science Of The Total Environment, 788, 147745 (20p.). Publisher's official version : https://doi.org/10.1016/j.scitotenv.2021.147745 , Open Access version : https://archimer.ifremer.fr/doc/00695/80752/