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Communication Dans Un Congrès Année : 2023

Granulate extraction effects on the benthic coarse sand community: The GIE-GMO site

Résumé

The seabed of the English Channel (EC) corresponds to an extensive network of paleo-valleys, partly filled at the present-day with coarse sediments, reaching sometimes several metres thick, which represent an important source of accessible aggregates. The extraction of these aggregates is currently experiencing significant growth along the French coast of the EC. Despite coarse sediments constitutes approximately 80% of the superficial composition of the EC, very few quantitative studies have been conducted on the benthic community which colonise these habitats. This lack of quantitative data and studies is primarily attributed to the challenges associated with sampling in this area, mainly due to its hydrodynamic conditions. In this context, the aim of this study was then to analyse the spatio-temporal evolution of benthic communities in relation to aggregate extraction. To achieve this, a Before-After Control-Impact (BACI) approach was employed. Thus, samples were collected before extraction between 2007 and 2010, then, two samplings were made during aggregate extraction in 2018 and 2023. The extraction activity was limited to a single strip within the concession, responsible of the refinement of the coarse sand. In 2023, two video acquisitions were carried out to assess the effects of marine aggregate extraction on the benthic community. Although the benthic diversity on the site appeared similar in 2023, a notable decrease in benthic abundance was observed. Techniques investigating the sediment-benthos relationship have also been applied to determine whether sediment reworking has had an impact on “grain size-sensitive” species, particularly those preferring coarse substrates.
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Dates et versions

hal-04274740 , version 1 (08-11-2023)

Identifiants

  • HAL Id : hal-04274740 , version 1

Citer

Nathan Chauvel, Aurore Raoux, Ferdinand Schlicklin, Pierre Weill, Laurent Dezileau, et al.. Granulate extraction effects on the benthic coarse sand community: The GIE-GMO site. Conférence Internationale d’Océanographie et 19ème Symposium Franco-Japonais d’Océanographie (COAST CAEN 2023), Oct 2023, Caen, France. pp.94. ⟨hal-04274740⟩
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