Reappraisal of the toxicity test method using the green alga Ulva pertusa Kjellman (Chlorophyta).

This study was aimed to develop an objective way of quantifying the reproductive status of the green macroalga, Ulva pertusa using a vital stain and programmed automated analysis (by Image J program). The EC50 values (with 95% CI), the concentrations of toxicants inducing a reduction of 50% in sporulation after 96 h exposure, from the newly developed method were similar to those obtained by the conventional method: 0.651 (0.598-0.705) mg l-1 for Cd, 0.144 (0.110-0.162) mg l-1 for Cu, 0.180 (0.165-0.195) mg l-1 for atrazine, 0.076 (0.049-0.094) mg l-1 for diuron and 30.6 (26.5-34.4) ml l-1 for DMSO, respectively. When the EC50 values from this study were compared to that those from literatures, the sensitivity for some toxicants was similar or higher than that of U. fasciata (1.930 mg l-1 for germination for Cd), U. armoricana (0.250 mg l-1 for Fv/Fm for Cu), U. reticulata (0.126-1.585 mg l-1 for growth for Cu), and U. intestinalis (0.650 mg l-1 for Fv/Fm for atrazine). The subjective views of the experimental performers can be eliminated using the newly developed method. The Ulva method gave consistent responses to Cu and Cd of internationally allowable ranges for effluents, implying that the method is a useful tool for monitoring industrial wastewaters containing these metals.