Assessment of the impact of dredge disposal sediment: towards a multicriteria index

The effects of marine sediment deposits in the context of harbor dredging are generally poorlydescribed by the ecological indices available to date, at least for part of the configurations ofdredged sediments / nature of the reception sites. In order to better assess these effects, theINDICLAP projects aims were to develop an indicator able to describe the changes of thebenthic environment due to sediment deposits. Initially inspired by the faunal index of Robertset al. (1998) then reworked in Dauvin et al. (2018) and Baux et al. (2020), the indicator hasbeen largely revised to a multicriteria indicator, based on the calculation of several indices andthe establishment of scores. This indicator takes into account the evolution of the benthicmacrofauna, the sedimentary changes during the deposits, the morphology and the bathymetryof the deposit zone via a comparison of crossed pairs of impacted or under-influenced stationsand control stations. For each of the three criteria mentioned, a score is established. Theweighted sum of the indices gives a final score, making it possible to establish the level ofimpact of the pressure exerted. This indicator, named D2SI for ‘Dredge Disposal SedimentIndex’, was calibrated on three sites undergoing very significant sediment deposits in theeastern part of the Bay of Seine (Normandy, France). However, to refine the calibration, itwould be necessary to calculate the indices on other dumping sites with different pressurelevels, and potentially other pairs of type of dredged sediments/type of recipient habitat

Assessing the ecological status of an estuarine ecosystem: linking biodiversity and food-web indicators

(IF 2.61 [2018]; Q1]International audienceDuring the last decades, the highly-anthropized Seine estuary has been impacted by modification of its habitats (building of a major extension of Le Havre harbour, i.e. Port2000) and a significant natural decrease in freshwater discharge. A Before/After analysis, using a toolbox of indicators, was applied to characterize the effects of both events on the estuarine ecosystem status. We selected from existing tool boxes several indicators derived from food web modelling or community composition data, such as biodiversity indicators, a guild-based index (i.e. Estuarine and Lagoon Fish Index ELFI) and ecological network analysis (ENA) indices. ENA and biodiversity indicators were applied on six spatial boxes describing the Seine estuary and its outlet. Results showed an increase in taxonomic and functional richness over time, mainly due to marinisation, and significant changes in food-web properties in relation to Port2000. ENA indices appeared as a promising method in ecological status assessment, especially for estuaries considered as inherently disturbed

Assessing the ecological status of an estuarine ecosystem: linking biodiversity and food-web indicators

(IF 2.61 [2018]; Q1]International audienceDuring the last decades, the highly-anthropized Seine estuary has been impacted by modification of its habitats (building of a major extension of Le Havre harbour, i.e. Port2000) and a significant natural decrease in freshwater discharge. A Before/After analysis, using a toolbox of indicators, was applied to characterize the effects of both events on the estuarine ecosystem status. We selected from existing tool boxes several indicators derived from food web modelling or community composition data, such as biodiversity indicators, a guild-based index (i.e. Estuarine and Lagoon Fish Index ELFI) and ecological network analysis (ENA) indices. ENA and biodiversity indicators were applied on six spatial boxes describing the Seine estuary and its outlet. Results showed an increase in taxonomic and functional richness over time, mainly due to marinisation, and significant changes in food-web properties in relation to Port2000. ENA indices appeared as a promising method in ecological status assessment, especially for estuaries considered as inherently disturbed

Interprétation française des Habitats marins d'intérêt Communautaire marins

L’identification et la cartographie des habitats marins est une étape indispensable pour les politiques de conservation du milieu marin, notamment au regard de la protection des Habitats marins d’Intérêt Communautaire (HIC) et de la gestion des sites Natura 2000 en mer désignés pour ces HIC. Pour le domaine marin de France métropolitaine, neufs HIC sont concernés mais leur définition européenne n’est pas suffisamment explicite pour bien les identifier (Bancs de sable à faible couverture permanente d’eau marine, Herbiers à Posidonies, Estuaires, Replats boueux ou sableux exondés à marée basse, Lagunes côtières, Grandes criques et baies peu profondes, Récifs, Structures sous-marines causées par des émissions de gaz, Grottes marines submergées ou semi-submergées). La « Cellule Habitats Benthiques » de PatriNat a coordonné une expertise collégiale pour stabiliser l’interprétation française des HIC marins. Des fiches d’interprétation synthétiques cadrent désormais la définition et les critères d’identification de ces habitats marins dans un rapport de référence. Plus d’une vingtaine d’experts issus d’instituts en lien avec la connaissance et la gestion de ces milieux ont participé à ce travail d’expertise (OFB, PatriNat, Ifremer, Conservatoires Botaniques, Tour du Valat, et Office de l'Environnement de la Corse). Ces nouvelles descriptions ainsi que les correspondances avec les autres typologies d’habitats seront diffusées sur les fiches habitats des unités HIC de l'INPN lors de la prochaine mise à jour du référentiel HabRef (v7)

Interprétation française des Habitats d'Intérêt Communautaire marins

La Directive Habitats-Faune-Flore (dite « DHFF », 92/43/CEE) a listé des grands types d’habitats naturels qui nécessitent des mesures de conservation, les Habitats naturels d’Intérêt Communautaire (HIC). Ces HIC sont définis au niveau européen dans le manuel d’interprétation des habitats de l’Union européenne (dit « EUR 28 »). Pour le domaine marin de France métropolitaine, neufs HIC sont concernés. Les Cahiers d’habitats dits « côtiers » constituaient la déclinaison française des HIC et faisaient référence jusqu’à présent au niveau national pour la gestion des sites Natura 2000 en mer. Ils présentaient cependant des lacunes de complétude importantes. Pour pallier ces lacunes, ce rapport présente une nouvelle approche pour identifier sans ambiguïté les habitats devant bénéficier de mesures de gestion au titre de la DHFF, en proposant une interprétation nationale détaillée des HIC marins qui permet d’établir les correspondances avec les unités d’habitats des typologies nationales et ainsi de s’affranchir de l’utilisation des Cahiers d’habitats côtiers. Chaque HIC marin présent en France métropolitaine fait ainsi l’objet d’une fiche d’interprétation qui inclut une définition nationale et les critères d’identification associés, complétés par des précisions méthodologiques, la bibliographie mobilisée et des photographies illustrant différentes expressions possibles de l’HIC sur le territoire national

Interprétation française des Habitats d'Intérêt Communautaire marins

La Directive Habitats-Faune-Flore (dite « DHFF », 92/43/CEE) a listé des grands types d’habitats naturels qui nécessitent des mesures de conservation, les Habitats naturels d’Intérêt Communautaire (HIC). Ces HIC sont définis au niveau européen dans le manuel d’interprétation des habitats de l’Union européenne (dit « EUR 28 »). Pour le domaine marin de France métropolitaine, neufs HIC sont concernés. Les Cahiers d’habitats dits « côtiers » constituaient la déclinaison française des HIC et faisaient référence jusqu’à présent au niveau national pour la gestion des sites Natura 2000 en mer. Ils présentaient cependant des lacunes de complétude importantes. Pour pallier ces lacunes, ce rapport présente une nouvelle approche pour identifier sans ambiguïté les habitats devant bénéficier de mesures de gestion au titre de la DHFF, en proposant une interprétation nationale détaillée des HIC marins qui permet d’établir les correspondances avec les unités d’habitats des typologies nationales et ainsi de s’affranchir de l’utilisation des Cahiers d’habitats côtiers. Chaque HIC marin présent en France métropolitaine fait ainsi l’objet d’une fiche d’interprétation qui inclut une définition nationale et les critères d’identification associés, complétés par des précisions méthodologiques, la bibliographie mobilisée et des photographies illustrant différentes expressions possibles de l’HIC sur le territoire national

Targeted monitoring in offshore windfarms — the need to understand cause–effect relationships in the marine benthos

In many European countries offshore windfarm projects are accompanied by obligatory environmental impact assessments, including baseline monitoring of the marine benthos and demersal fish. The effects of offshore windfarm developments on the benthic system are complex. However, legal baseline monitoring merely allows for net effect descriptions but not for identifying and understanding the underlying processes. Instead, key processes should be identified and become subject to hypotheses‐based target monitoring and/or experimental studies in order to make environmental impact assessments more efficient and reduce duplication internationally. We compiled an overview over the anthropogenic activities associated with the construction and operation of offshore windfarms and identified cause–effect relationship to facilitate the development of specific hypotheses. We expect offshore windfarming activities to modify the geomorphological and hydrodynamic environment at different temporal and spatial scales. The environmental effects will have consequences for the behaviour and physiology of benthic organisms, including demersal fish, restructuring natural local populations and communities. Major effects on biological production, biogeochemical processes, as well as on structure and function related to biodiversity, are expected from the massive colonization of the artificial underwater constructions by a specific hard‐bottom fauna which is naturally missing in soft sedimentary habitats. Understanding the mechanisms behind these changes is a priority for assessing and predicting the ecological implications for the benthic system. Such predictions may help to develop science‐based mitigation actions

A call for hypotheses‐based benthos research in offshore windfarm environmental impact studies

Offshore windfarms are expected to affect substantially the structure and functioning of marine ecosystems. Collision risks for migrating birds and noise impact on marine mammals and fish are issues of major public concern. Less charismatic organisms, however, from marine algae through to benthic invertebrates and demersal fish receive far less attention. We contend that the benthos deserves much greater attention owing to the numerous ecosystem goods and services, such as marine biodiversity and long‐term carbon storage and natural resources (e.g. for fish, birds, mammals, and finally humans), that are intimately linked to the benthic system. The installation and operation of extensive offshore windfarms in shallow shelf seas will initiate processes which are expected to affect benthic communities over various spatial and temporal scales. Extensive baseline monitoring programmes allow observations of structural changes to benthic communities, but this is a post‐hoc approach. To gain a mechanistic understanding of these processes that enables us to explain the observed changes, specific target monitoring and well‐designed experimental studies are required. In this conceptual talk we will discuss specific cause–effect relationships in the marine benthos arising from the anthropogenic activities associated with offshore windfarms. The identification of cause–effect relationships is the prerequisite for an efficient, hypothesis‐driven approach towards the disentanglement of the various effects of offshore windfarms on the marine benthos as well as on the whole ecosystem

ICES Workshop on the effects of offshore wind farms on marine benthos (WKEOMB) - Facilitating a closer international collaboration throughout the North Atlantic region

The workshop aimed at bringing experts working in the field of offshore wind farms – benthos together for the first time in order to get an overview on the state of the art. This was achieved by an extended poster session. The second issue of WKEOMB was to identify knowledge gaps and evaluating monitoring strategies. This issue was evaluated by disentangling the cause-effect relationships affected by the pressures of the activities during the construction and operation phase of offshore wind farms. All cause-effect relationships were summarized in a schematic presentation. The identifi-cation and a comprehensive overview of cause-effect relationships is a prerequisite for an efficient, hypothesis driven approach towards the disentanglement of the vari-ous effects of offshore wind farms on the marine benthos as well as on the whole eco-system. Further, manifold cause-effect relationships were prioritized based on three main research themes, biological resources – biogeochemical reactions – biodiversity, disentangled by the participants as relevant. An important outcome of the workshop is that benthos receives by far too little atten-tion compared to other ecosystem components (e.g. seabirds, marine mammals), al-though it contributes to a great extent to marine ecosystem services and goods, e.g. biodiversity, long-term carbon storage and trophic supply for higher trophic-level species. A second main outcome of WKEOMB was that legal baseline monitoring merely allows for net-effect descriptions but not for identifying and understanding the underlying processes. Key processes should be, thus, identified and become sub-ject to hypotheses-based target monitoring and/or experimental studies