INFLUENCE OF THE FECAL POLLUTION OF MARINE-SEDIMENTS ON THE MICROBIAL CONTENT OF SHELLFISH

To determine the influence of faecally-contaminated sediments on the microbial content of shellfish, several indicator and pathogenic microorganisms were monitored over a period of 19 months in the Guadalhorce estuary (Malaga, South of Spain). All the microorganisms studied were found to be present in greater numbers in sediments and shellfish than in the overlying water. The occurrence of the pathogens studied in shellfish does not appear to be correlated with the levels of any particular indicator group in sediments, except for sulphite-reducing clostridia and faecal streptococci, which showed a significant relationship with the presence of Salmonella and Aeromonas hydrophila in shellfish, respectively. The results obtained in the present study suggest that an evaluation of the presence of indicator and pathogenic microorganisms in sediment may provide additional insight into long-term water quality conditions, but they do not improve the indication of pathogen presence in shellfish compared with the study of the seawater or the direct analysis of shellfish.