Viable heterotrophic bacteria in water and sediment in ‘Mar Piccolo’ of Taranto (Ionian Sea, Italy)

Samples of water and sediment were collected from October 1996 to September 1997 in ‘Mar Piccolo’ of Taranto (Ionian Sea, Italy). Mar Piccolo is a semi‐enclosed basin subject to pollution and receives a considerable amount of sewage and industrial waste. Qualitative and quantitative analyses of the composition of the microbial flora were conducted on samples from six stations. The highest bacterial densities, in water and in sediment samples, were found in summer and the lowest, in autumn. Among Gram‐negative bacteria, the predominant genus was Aeromonas;Photobacterium and Pseudomonas were also found. Gram‐positive bacilli were abundant at all sampling points. Faecal contamination indicators demonstrated that all the stations examined in Mar Piccolo are influenced by anthropogenic pollution throughout the year.