Evaluation of a battery of marine species-based bioassays against raw and treated municipal wastewaters

The present study evaluates a battery of marine species-based bioassays against chemically characterized municipal wastewater samples (raw and WWTP treated). We estimated Dunaliella tertiolecta growth rate inhibition (24-96 h IC50 values), Artemia franciscana immobilization (24h LC50 values), mussel hemocytes viability and lipid peroxidation enhancement (in terms of neutral red retention assay/NRRT and malondialdehyde/MDA content, respectively) in influent- and WWTP effluent-treated species. We found algal growth arrest and stimulation respectively, almost similar 24hLC50 values in Artemia sp., and significantly higher adverse effects (in terms of NRRT and MDA levels) in influent-treated mussel hemocytes. Furthermore, the estimation of hatchability, yolk-sac larvae mortality (24-120 hLC50) and spinal deformities (SD) in sea bream Sparus aurata showed slight variations over time, with the lowest LC50 and SD50 (representing spinal deformities at 50% of yolk-sac larvae) values to be observed in influent-treated larvae at 120 h. Data interpretation (both chemical and biological) revealed that toxic endpoints, such as NRRT50, 96hIC50Dun, 120hLC50Sparus and 120hSD50Sparus, significantly related to WWTP removal efficiency and further mediated by the presence of dominant compounds, such as As and Cr, could be used for identifying main components of toxicity in wastewaters.