title: Improving marine biodiversity offsetting: A proposed methodology for better assessing losses and gains.
abstract: Although the limitations of implementing the mitigation hierarchy have been widely discussed in scientific literature, these studies have drawn mainly on feedback concerning terrestrial ecosystems. In the case of development projects in marine and coastal environments, certain issues must be tackled to improve existing practice. This article focuses on the methodologies used to assess both the ecological losses resulting from a development project and the ecological gains generated by an offset measure. The originality of this article is to propose a standardized, operational approach regardless of the development project and the ecosystem impacted that (i) enhances avoidance and reduction efforts and (ii) assesses biodiversity offset needs based on data available in Environmental Impact Assessments (EIAs). The proposed hybrid method combines a multi-criteria analysis of the state of the environment, inspired by the Unified Mitigation Assessment Method (UMAM), and a more accurate assessment at indicator level inspired by Habitat Equivalency Analysis (HEA). The steps of the method, from the selection of biophysical indicators to offset sizing, are described and are then applied to two EIA case studies: one related to a port extension and the other to an offshore wind farm.
authors.affiliation: UMR Amure, Université de Brest, UMR M101, EDF Energies Nouvelles, 12 rue de Kergoat, Bâtiment B, CS 93837, 29238 Brest Cedex 3, France. Electronic address: adeline.bas@gmail.com.
authors.forename: Adeline
authors.initials: A
authors.lastname: Bas
authors.affiliation: CREOCEAN, CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, Route de Mende, 34199, Montpellier Cedex 5, France. Electronic address: celine.jacob@cefe.cnrs.fr.
authors.forename: Céline
authors.initials: C
authors.lastname: Jacob
authors.affiliation: UMR Amure, Université de Brest, UMR M101, 12 rue de Kergoat, Bâtiment B, CS 93837, 29238 Brest Cedex 3, France. Electronic address: julien.hay@univ-brest.fr.
authors.forename: Julien
authors.initials: J
authors.lastname: Hay
authors.affiliation: CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, Route de Mende 34199, Montpellier Cedex 5, France. Electronic address: sylvain.pioch@gmail.com.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Pioch
authors.affiliation: CREOCEAN, Les Belvédères, Bâtiment B, 128, avenue de Fès, 34080 Montpellier, France. Electronic address: thorin@creocean.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Thorin
mesh_terms: D044822:Biodiversity; D003247:Conservation of Natural Resources / Q000379:methods*; D004463:Ecology; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans
keywords: Environmental impact assessment; Marine and coastal ecosystems; Mitigation hierarchy; Offset sizing