Francesca Rossi1, Alix Varenne2,3, Anais Gudefin3, Marie-Yasmine Dechraoui Bottein2
1Stazione Zoologica A. Dohrn, Italy - 2Université Côte d’Azur, France - 3Ecocean SAS, France
Coastal development is increasing worldwide, significantly impacting diversity and ecosystem functioning, including the flow of energy and nutrients (trophic connectivity) across habitats. Ports and marinas are examples of intense coastal development, where natural rocky shores and sandy beaches are largely replaced by man-made structures. Along some Mediterranean coasts, a common feature is nowadays a fragmented seascape with small marinas interspersed within natural shores and Posidonia oceanica meadows. Information on the trophic connectivity between Posidonia oceanica meadows and adjacent marinas remains poorly studied. Additionally, artificial fish habitats (AFH) are often installed within marinas with the expectation of attracting fishes, enhancing larval settlement and providing food and shelter to juveniles and subadults. By modifying fish assemblages, AFH may impact the flow of organic matter across adjacent habitats. In this study, we investigated the carbon and nitrogen flow between marinas and adjacent Posidonia oceanica meadows using stable isotope analyses, with a particular focus on whether AFH could modify this subsidy. Along the Northern-Western Mediterranean Sea, we sampled 4 sites that included a seagrass meadow adjacent to a marina equipped or unequipped with AFH. We measured the isotopic composition of Posidonia leaves and epiphytes, particulate and sedimentary organic matter and macroalgae (when present), within the marina and the seagrass meadow. We also examined the trophic relationships between these sources and Sparidae fish species. While fish isotopic niches varied between sites, they were similar between seagrass meadows and inside the marina, indicating the fish fed across habitats and potentially act as vehicle of trophic exchange. Here we present the first results of this work, highlighting the role of fish in organic matter exchange between habitats.
Biography
Francesca Rossi is a benthic marine ecologist mainly working on the impacts and the functioning of coastal ecosystems, with a specific regard to trophic relationships. She is interested in conservation and restoration ecology, with the believe that fundamental ecology is key for environmental protection. He main approach is experimental quantitative ecology.