Evaluating ecosystem functioning of a long-term dumping site in the Bay of Seine (English Channel)

Type Article
Date 2020-08
Language English
Author(s) Raoux Aurore1, Baux Noémie1, 2, 3, Pezy Jean-Philippe1, Balay Pierre4, Lesourd Sandric1, Dauvin Jean-Claude1
Affiliation(s) 1 : Normandie Univ, UNICAEN, Laboratoire Morphodynamique Continentale et Côtière, CNRS UMR 6143 M2C, 24 rue des Tilleuls, 14000 Caen, France
2 : Normandie univ., UNICAEN, Laboratoire des Sciences Appliquées de Cherbourg, EA 4253, 50100 Cherbourg, France
3 : Conservatoire National des Arts et Métiers, INTECHMER, 50100 Cherbourg, France
4 : Cellule de Suivi du Littoral Normand, CSLN, 53 Rue de Prony, 76600 Le Havre, France
Source Ecological Indicators (1470-160X) (Elsevier BV), 2020-08 , Vol. 115 , P. 106381(11p.)
DOI 10.1016/j.ecolind.2020.106381
Keyword(s) Dredged material disposal, Harbour activities, Ecopath model, Ecological Network, Analysis, Benthic indicators, Impacted zone, Non-impacted zone, Bay of Seine

The impact of 70 years of dumping harbour dredged material on ecosystem functioning was compared to a control site (non-impacted zone). A combination of indices (Shannon-Wiener diversity, Pielou evenness, BO2A, AMBI benthic indices) and modelling (Ecopath models) generated Ecological Network Analysis indices were used to detect the dumping operations effects. ENA indices showed that dumping operations appear to have a relatively limited impact on the structure and flow pattern of the local food web. In fact, only small variations between the two sites are revealed by a comparison of ENA indices between the impacted and non-impacted zone. This result could be explained by the fact that the Bay of Seine is historically characterized by a high level of human activities, which have led to an increase in resilience through time to face these multiple pressures. AMBI and BO2A indices (of the sediment fauna) did not allow a clear distinction between impacted and non-impacted zone while species richness, abundance, biomass and Shannon-Wiener diversity index values were significantly higher in the non-impacted zone which is in accordance with the small variations of ENA indices between the two zones and revealed a local and limited impact. Our results suggested that a combination of several tools should be used to detect the true impacts and to conduct diagnosis of the ecological status of dumping deposit in a coastal area permanently stressed under natural and anthropogenic forcing.

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