Historical control data of ecotoxicological test with the copepod Tigriopus fulvus

The aim of this study was to evaluate the variability of naupliar mortality and sensitivity of T. fulvus to copper sulphate, (positive control), reared in laboratory by using a series of historical control data (HCD). Historical data were obtained by a dataset of 68 mortality acute tests (negative control) and by about 30 values of LC50 determined at 24-48 and 96 h (positive control with copper sulphate), in over 12 years. Data, arranged in Shewhart-like control charts, displayed a mean mortality of 3.53% in negative controls, well below the reference limit of <= 10%, with a low level of variability over time. Lethal concentration (LC50) for copper sulphate showed a stable mean of 0.67 +/- 0.12 at 24 h, 0.30 +/- 0.08 at 48 h and 0.12 +/- 0.05 mg Cu++/L, over time. These data confirm Tigriopus fulvus as a good bioindicator, even after years of culturing in laboratory conditions, since even over time, its responses to negative and positive controls (copper) have not undergone changes.