Microbiome variations at the clams-sediment interface may explain changes in local productivity landing of the clam Chamelea gallina in the north adriatic sea

The marine coastal ecosystems provide a wide range of ecologically and economically important ecosystem services. These ecosystems' capacity to deliver essential services to society is already under stress, being threatened by anthropic and climate change pressures. Coastal ecosystems around the world are in danger due to rising temperature, ocean acidification and increase of pollutants discharged into seawater. To support the health of coastal ecosystems, a key role is played by marine holobionts. These habitat-forming organisms are primary producers and are at the base of the coastal trophic chains, providing the support to entire ecosystems. The health and services of marine coastal ecosystems are linked to microbial communities that live in association with marine holobionts. The mutual symbiosis between host and its microbial communities supports nutrition, protection, and development of the host. We propose a model for ecosystem service restoration that leverages microbiomes from healthy holobionts already adapted to environmental fluctuations and anthropogenic stressors. As a case study to investigate population dynamics in a stressed marine ecosystem, we focused on the bivalve Chamelea gallina, a commercially valuable clam species that experiences recurrent mass mortality events along the Emilia-Romagna coastline of the Adriatic Sea. This Ph.D. research aims to identify and characterize stress-response and adaptive indicators that may serve as tools for restoring the health of northern C. gallina populations. Through a series of controlled aquarium experiments, we present preliminary evidence supporting the prebiotic effect of microbiomes derived from healthy holobionts that are already acclimated to similar environmental stress conditions. Finally, we propose an innovative microbiome-based management strategy to sustain and enhance the productivity of C. gallina fisheries in the Adriatic Sea. This approach involves the identification and maintenance of a probiotic microbial niche, offering a promising framework for the conservation and resilience of benthic species under increasing environmental pressure.