Microbial characteristics of marine sediments in bathing area along Pesaro-Gabicce coast (Italy)

Aims:The aim of the present work was to study the presence of human pathogen microorganisms in marine sediments at two bathing beaches and to compare the data obtained to grain size analyses of the sediments in order to observe any existing relationships between grain size and microbial charge Methods: The sediment samples were collected in two small bays along the central Adriatic coast, wherebreakwaters had been built for the purpose of halting marine erosion. Faecal contamination indicators, Salmonella and Vibrio species, enteric viruses were investigated using standard techniques for isolation and identification. The grain size was determined using calibrated sieves and _Sedigraph_ device. Results: The values of faecal contamination indices varied depending on the area and in some samples overstepped legislative limits. Salmonella was never found. Vibrio was found in several samples and a considerable presence of enteric viruses was registered. The micro-organisms were preferentially abundant in fine sediments. Conclusions: Marine sediments can represent an important reservoir of allochthonous and marine microorganisms and the microbial charge correlates with the characteristics of the sediments. There was not a correlation between allochthonous microorganisms such as Enterobacteriaceae and indigenous microorganisms such as Vibrio. Significance and Impact of the Study: This study indicates that in addition to the faecal contamination indicators and the specific pathogens provided for by the present Italian legislation, other biological indicators should be investigated. In addition, being marine sediments an important microbial reservoir, it is important to analyse them before defining the quality of coastal areas.