Development of a growth inhibition test with the marine and brackish water red alga Ceramium tenuicorne

The marine red macroalga Ceramium tenuicorne is cosmopolitan and naturally found in both brackish and marine waters. A growth inhibition test with this species can be carried out in salinities from 4‰ to 32‰. The species is easily held in culture in the laboratory and the test can be performed in a completely defined medium. The robustness of the method is good with a CV of 14.6% of the controls. The EC calculations can be performed on linear regression on the length data. EC50 values of repetitive tests for zinc (20-33 μg Zn2+/l in 7‰ and 32-61 μg Zn2+/l in 20‰) and copper (1.9-3.8 Cu2+/l in 7‰ and 7.9-13 Cu2+/l in 20‰) show high sensitivity. This test is a good complement to any test battery with the purpose of estimating the hazard of substances to the brackish and marine environment.