@article {5037, title = {Benthic and fish aggregation inside an offshore wind farm: Which effects on the trophic web functioning?}, journal = {Ecological indicators}, volume = {72}, year = {2017}, month = {01/2017}, pages = {33-46}, abstract = {

As part of the energy transition, the French government is planning the construction of three offshore wind farms in Normandy (Bay of Seine and eastern part of the English Channel, north-western France) in the next years. These offshore wind farms will be integrated into an ecosystem already facing multiple anthropogenic disturbances such as maritime transport, fisheries, oyster and mussel farming, and sediment dredging. Currently no integrated, ecosystem-based study on the effects of the construction and exploitation of offshore wind farms exists, where biological approaches generally focused on the conservation of some valuable species or groups of species. Complementary trophic web modelling tools were applied to the Bay of Seine ecosystem (to the 50 km(2) area covered by the wind farm) to analyse the potential impacts of benthos and fish aggregation caused by the introduction of additional hard substrates from the piles and the turbine scour protections. An Ecopath ecosystem model composed of 37 compartments, from phytoplankton to seabirds, was built to describe the situation {\textquoteleft}{\textquoteleft}before{{\textquoteright}{\textquoteright}} the construction of the wind farm. Then, an Ecosim projection over 30 years was performed after increasing the biomass of targeted benthic and fish compartments. Ecological Network Analysis (ENA) indices were calculated for the two periods, {\textquoteleft}{\textquoteleft}before{{\textquoteright}{\textquoteright}} and {\textquoteleft}{\textquoteleft}after{{\textquoteright}{\textquoteright}}, to compare network functioning and the overall structural properties of the food web. Our main results showed (1) that the total ecosystem activity, the overall system omnivory (proportion of generalist feeders), and the recycling increased after the construction of the wind farm; (2) that higher trophic levels such as piscivorous fish species, marine mammals, and seabirds responded positively to the aggregation of biomass on piles and turbine scour protections; and (3) a change in keystone groups after the construction towards more structuring and dominant compartments. Nonetheless, these changes could be considered as limited impacts of the wind farm installation on this coastal trophic web structure and functioning. (C) 2016 Elsevier Ltd. All rights reserved.

}, issn = {{1470-160X}}, doi = {10.1016/j.ecolind.2016.07.037}, author = {Raoux, Aurore and Samuele Tecchio and Pezy, Jean-Philippe and G{\'e}raldine Lassalle and Degraer, Steven and Wilhelmsson, Dan and Cachera, Marie and Ernande, Bruno and Le Guen, Camille and Haraldsson, Matilda and Karine Granger{\'e} and Le Loc{\textquoteright}h, Francois and Dauvin, Jean-Claude and Nathalie Niquil} } @article {5039, title = {Evaluating ecosystem-level anthropogenic impacts in a stressed transitional environment: The case of the Seine estuary}, journal = {ECOLOGICAL INDICATORS}, volume = {61}, year = {2016}, month = {02/2016}, pages = {833-845}, abstract = {

During 2002-2005, a new container terminal in the commercial harbour of Le Havre, named "Port2000", was built on the northern flank of the Seine estuary, northern France. This extension is already known to have modified the estuary current and sediment dynamics, as well as reducing biomass of the suprabenthos assemblage, for the whole downstream part of the system. However, studies on other biotic communities were largely inconclusive, and an ecosystem-wide analysis was still lacking. Here, we performed a before/after study of ecosystem dynamics of the different habitats of the Seine estuary, using a Linear Inverse Modelling technique (LIM-MCMC) to estimate all flows occurring in the food web. Ecological Network Analysis indices were calculated, summarising ecosystem functioning traits and giving indications about the habitat health status. Results showed that the southern flank (FS, Fosse Sud) exhibits all characteristics to be considered as the least stressed habitat of the estuary: system activity and functional specialisation of flows were stable between periods, ecosystem recycling processes and detrital dynamics were also stable; an increase in trophic specialisation (decrease in system omnivory) was the only change confirming a general ecological succession. The northern flank (FN, Fosse Nord), where the actual terminal was built, showed a food web with increased importance of lower trophic levels (increased detritivory and carbon recycling), increased stability and flow efficiency, but possibly regressed to a previous step in ecological succession. In the central navigation channel (CH), patterns of network indices were overall inconclusive and the general image is one of a constantly shifting food web, a condition possibly caused by the year-round dredging activities. The functioning of the Seine estuary especially of FN and FS - seems to have been modified by the combination of harbour construction and the related mitigation measures. Network indices partially captured this combination of changes and, although not fully operational yet, they are promising tools to comply with the European Union mandate of defining ecosystem health status. (c) 2015 Elsevier Ltd. All rights reserved.

}, issn = {{1470-160X}}, doi = {{10.1016/j.ecolind.2015.10.036}}, author = {Samuele Tecchio and Chaalali, Aur{\'e}lie and Raoux, Aurore and Rius, Armonie Tous and Lequesne, Justine and Girardin, Valerie and G{\'e}raldine Lassalle and Cachera, Marie and Riou, P and Lobry, Jeremy and Dauvin, Jean-Claude and Nathalie Niquil} } @article {5042, title = {The mosaic of habitats of the Seine estuary: Insights from food-web modelling and network analysis}, journal = {ECOLOGICAL MODELLING}, volume = {312}, year = {2015}, month = {09/2015}, pages = {91-101}, abstract = {

Ecological network analysis was applied in the Seine estuary ecosystem, northern France, integrating ecological data from the years 1996 to 2002. The Ecopath with Ecosim (EwE) approach was used to model the trophic flows in 6 spatial compartments leading to 6 distinct EwE models: the navigation channel and the two channel flanks in the estuary proper, and 3 marine habitats in the eastern Seine Bay. Each model included 12 consumer groups, 2 primary producers, and one detritus group. Ecological network analysis was performed, including a set of indices, keystoneness, and trophic spectrum analysis to describe the contribution of the 6 habitats to the Seine estuary ecosystem functioning. Results showed that the two habitats with a functioning most related to a stressed state were the northern and central navigation channels, where building works and constant maritime traffic are considered major anthropogenic stressors. The strong top-down control highlighted in the other 4 habitats was not present in the central channel, showing instead (i) a change in keystone roles in the ecosystem towards sediment-based, lower trophic levels, and (ii) a higher system omnivory. The southern channel evidenced the highest system activity (total system throughput), the higher trophic specialisation (low system omnivory), and the lowest indication of stress (low cycling and relative redundancy). Marine habitats showed higher fish biomass proportions and higher transfer efficiencies per trophic levels than the estuarine habitats, with a transition area between the two that presented intermediate ecosystem structure. The modelling of separate habitats permitted disclosing each one{\textquoteright}s response to the different pressures, based on their a priori knowledge. Network indices, although non-monotonously, responded to these differences and seem a promising operational tool to define the ecological status of transitional water ecosystems. (C) 2015 Elsevier B.V. All rights reserved.

}, issn = {{0304-3800}}, doi = {{10.1016/j.ecolmodel.2015.05.026}}, author = {Samuele Tecchio and Rius, Armonie Tous and Dauvin, Jean-Claude and Lobry, Jeremy and G{\'e}raldine Lassalle and Morin, Jocelyne and Bacq, Nicolas and Cachera, Marie and Chaalali, Aur{\'e}lie and Villanueva, Maria Ching and Nathalie Niquil} }