Abstract
Coastal development is one of the major threats to coastal ecosystems because it replaces natural habitats with artificial structures, thereby having important consequences for biodiversity and ecosystem services. Ecological engineering solutions such as artificial nurseries placed in highly artificial coastal habitats such as ports and marinas could contribute to the ecological rehabilitation of these systems. Even if changes in local diversity have been documented in previous studies, there is still a lack of information on how the presence of these structures could affect the export of biomass to adjacent habitats. This project aims at exploring how organic material is exported from small marinas to adjacent vegetated habitats in the Mediterranean Sea and how the presence of artificial nurseries modifies this export. We have sampled 4 marinas located on the Eastern French Mediterranean coast (PACA region) during the autumn of 2022. Two of the marinas had been equipped with specific artificial nurseries (Biohut® made by ECOCEAN company) since 2019, with the purpose of improving coastal fish recruitment. The two remaining marinas were used as control. In each site, we sampled particulate organic matter in the water column and on the surface of the sediment inside the marina (close to the mouth) and in Posidonia oceanica habitats situated nearby (within 300 m) and further away (c.a. 1 km). We also sampled for fishes and for their potential food sources. Samples are being processed for bulk stable isotope analyses of carbon and nitrogen and for fish stomach content. Here we will illustrate the sampling design and some preliminary results. This project contributes to a better understanding of the trophic connectivity between artificial and natural habitats and can provide valuable information on the role of ecological engineering solutions in this connectivity.purpose of improving coastal fish recruitment. The two remaining marinas were used as control. In each site, we sampled particulate organic matter in the water column and on the surface of the sediment inside the marina (close to the mouth) and in Posidonia oceanica habitats situated nearby (within 300 m) and further away (c.a. 1 km). We also sampled for fishes and for their potential food sources. Samples are being processed for bulk stable isotope analyses of carbon and nitrogen and for fish stomach content. Here we will illustrate the sampling design and some preliminary results. This project contributes to a better understanding of the trophic connectivity between artificial and natural habitats and can provide valuable information on the role of ecological engineering solutions in this connectivity.