A Korean strain of Alexandrium affine (TY150902) was exposed to adult Thamnaconus modestus and Haliotis discus hannai for a comparative toxicity evaluation. Tests were done in two subsequent ways in the chamber (70 L carrying 30 L alga) for 24 hours. The first test was to find the first damage concentration (FDC) at 4 allocations (0, 1.25, 2.5, or 5.0 ¡¿ 103 cells mL-1) at 20¡É. The second was to detail at a median concentration (MC) between FDC and its previous concentration at 20 and 25¡É. In the first test FDC was 5.0 ¡¿ 103 cells mL-1 for both species, calculating 3.75 ¡¿ 103 cells mL-1 as an MC in common. The algal toxicities at FDC were species-specific with bigger toxicity to the finfish. Toxicities at MC were also species-specific: harmless to the shellfish and temperature-dependently toxic to the finfish with mortalities of 20% at 20¡É and 0% at 25¡É. These results elucidated that A. affine is no longer harmless with an estimated potent concentrations near MC for the finfish and close to FDC for the shellfish. In the toxicity evaluation, particularly to T. modestus, temperature should be taken into account as it might be a parameter influencing the algal damage potential.
