Luminescent bacteria as indicators of marine water quality: Preliminary results from the Campania coastal waters

This study reports preliminary results on the concentration of marine heterotrophic bacteria (Apparent Bacterial Concentration, ABC), and their luminous fraction (Apparent Luminous Bacterial Concentration, ALBC), here expressed as percentage of luminous bacteria (LB%), in coastal waters along the Campania shoreline. The results show that the Campania coastal area includes sectors characterised by different levels of water quality, following a geographical gradient from north to south. LB% appears related to inputs of pollution, showing low values in contaminated areas (<4%), and higher values in unimpacted waters (8-38%). In most cases, low values of this parameter were associated with high concentrations of faecal coliforms, suggesting that the LB% index is particularly sensitive to organic pollution. The pattern of water quality as estimated by LB% is in a strong agreement with previous results obtained by applying, in the same areas, other kinds of approaches, such as trophic indexes and algal bioassays. However, the main limit of LB% is that it should be used in the frame of a site-dependent approach: it cannot be used to identify absolute conditions of 'good' and 'bad' water quality, but just to highlight the extent of the 'deviation from integrity' characterizing each site in relation to the whole study area.