Study of the water quality close to urban sewers in eastern Ligurian coast by means of bioluminescence tests and conventional analyses

Five municipal sewers with small flow rates (Manarola, Riomaggiore, Portovenere, Tellaro, Bocca di Magra) were studied using the Microtox^® test and a bacterial luminescence bioassay in order to evaluate the water quality in these areas of the eastern Ligurian coast. The work was performed including chemical analysis, microbiological and ecotoxicological assays. Analyses were carried out on both the effluents and the water body close to the pipe discharge. None of the measured chemical parameters exceeded the permitted limits, both in the effluents and in the seawater samples, even if some slightly critical situations were highlighted by the Microtox^® test on the effluents. On the other hand, the Microtox^® appeared to be less effective than another ecotoxicological assay based on the luminescent fraction of epibacteria for the evaluation of seawater quality. The good water quality of the considered areas was assessed although a slightly worse condition was encountered in Bocca di Magra.