engleski

Occurrence and distribution of bacterial indicators for the assessment of the impact of mariculture in the Adriatic Sea

Water quality is one of the main precondition for sustainable mariculture. Mariculture activities may introduce excessive nutrients into surrounding water and increased deposition on the sediment. Such changes in marine environment lead to stress and open possibilities for opportunistic infections caused by fish pathogens (Vibrio). The study examined occurrence and distribution of bacterial indicators in sediments and compared these counts to those in the water column at the farm and control site in the Bay of Mali Ston (Adriatic Sea, Croatia) during spring, summer and autumn in 2016. Bacterial indicators (heterotrophic bacteria, total coliforms, Escherichia coli, enterococci and Vibrio) have been investigated in relation to physical and geochemical parameters of marine water (temperature, dissolved oxygen, pH, salinity, total phosphorus and nitrogen, silica and silicon dioxide, and particulate matter) and sediments (organic matter content, grain size and mineral composition). Physical and geochemical parameters showed seasonal fluctuations at both sampling sites, following changes in temperature. In the sediments, number of total coliforms and E. coli were higher at marine farm location, whereas in the water column, number of total coliforms, heterotrophic bacteria and Vibrio were significantly higher at the control site. Significantly higher number of total coliforms, E. coli, enterococci and Vibrio was observed during the autumn. Occurrence of V. gigantis, V. harveyi, V. pomeroyi, V. parahemoliticus in the sediments and water column illustrated that sediments could serve as reservoir for pathogens and further studies are needed to assess the risk of infection and impact on marine environment.

bacterial indicators ; Adriatic Sea ; mariculture ; Vibrio

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