Ecosystem approach of artificial reef through trophic web modelling

Abstract

Along the French coast of the Atlantic and English Channel in a high tidal regime, only a limited number of Artificial Reefs (ARs) had been immerged in very few localities in the aim to increase the local production of fisheries of such hard artificial substratum. Moreover, ARs design have been planned to increase the diversity, abundance and biomass of benthic species associated to hard-bottom. Does the deployment of such artificial structure improve the production and ecological functioning on such equipped areas? Trophic models describing the interaction between species at different trophic levels and based on the quantification of energy flow and matter in ecosystems are able to respond to this question. They allow the application of numerical methods for the characterization of emergent properties of the ecosystem, also called Ecological Network Analysis (ENA). Usually, these indices have been proposed as ecosystem health indicators as they have been demonstrated to be sensitive to different impacts on marine ecosystems. Here, Ecopath ecosystem models composed of 23 compartments, from phytoplankton to mammals, are built to describe the situation “Before” and “After” the implantation of ARs in two areas: the Rade of Cherbourg in the central part of the English Channel along the French coast, and in the south of the Bay of Biscay along the Landes coast. In addition, ENA indices are calculated for the two periods, “before” and “after” the implantation of artificial reefs to compare network functioning and the overall structural trophic web properties. In both areas, increase of benthic and fish compartments insure an increase of the system maturity; nevertheless, the high surge of planktinovorous fishes on the Landes AR showed a protection role of such AR than changes of planktonic preys.

Coastal greening of grey infrastructure: an update on the state-of-the-art

“…Limited research effort has focussed on the influence of GGI interventions on ecological functionality, including fitness and reproduction, trophic structure (but see Espinosa et al, 2020;Sedano et al, 2020a,b;Raoux et al, 2022) or ecological connectivity. GGI interventions may for example, serve as hubs for sources of propagules (Reddy, 2022), or facilitate novel interactions among species (Klein et al, 2011) through a failure to support viable populations of key intertidal grazers (Moreira et al, 2006).…”

“…Moreover, GGI may negatively affect surrounding natural habitats. If, for example, GGI promotes novel communities with high filtration capacity as observed on artificial structures (Layman et al 2014), it can potentially impact marine food webs beyond the footprint of the structure (Malerba et al, 2019;Raoux et al, 2022); conversely societal benefits may be delivered by increasing water quality, especially in enclosed urban water bodies (Wilkinson et al 1996). Further research is therefore needed in this area (Riascos et al, 2020), including differing viewpoints of different constituencies of stakeholders.…”

“…-Consideration of ecosystem functioning metrics such as biofiltration (Malerba et al, 2019;Riascos et al, 2020;Rouse et al, 2020;Vozzo et al, 2021a;Bulleri et al, 2022;Raoux et al, 2022;Mayer-Pinto et al, 2023).…”

“…-Considering socio-economic benefits Evans et al, 2017;Kienker et al, 2018;Evans et al, 2019;Morris et al, 2019;Strain et al, 2019;Sawyer et al, 2020;Fairchild et al, 2022;Accola et al, 2022a,b;Salaün et al, 2022;Aguilera et al, 2023b). -Consideration of other metrics such as trophic structure (Espinosa et al, 2020;Sedano et al, 2020a,b;Raoux et al, 2022), sedimentation (Bone et al, 2022b;Martinez et al, 2022), transport of wrack (Strain et al, 2018b;Critchley et al, 2021), litter accumulation (Aguilera et al, 2016(Aguilera et al, , 2018(Aguilera et al, , 2023a, use by terrestrial predators or pest species (Aguilera et al, 2023a), early life stage usage (Mafanya, 2020;Reddy, 2022).…”