Acute toxicity of antifouling agents CuSO4, ZnPT, and CuPT on marine diatoms Skeletonema costatum and Navicula sp.

Substrates exposed to the marine environment frequently undergo biofouling, which can result in both pollution and economic losses. Biofouling can be prevented using antifouling paints to inhibit the growth of adherent organisms. Since the ban of tributyltin, most antifouling agents are primarily copper -based mixtures, such as ZnPT and CuPT. To assess the environmental impacts of various antifouling agents, toxicity tests were conducted using the diatoms Skeletonema costatum and Navicula sp. For toxicity assessment, diatoms were exposed to CuSO₄, ZnPT, and CuPT for 72 h, yielding EC₅₀ values for S. costatum of 1,524 μg/L, 1.06 μg/L, and 0.46 μg/L, respectively, and for Navicula sp. of 793.8 μg/L, 254.8 μg/L, and 75.93 μg/L, respectively. Both diatoms exhibited sensitivity in the order CuPT > ZnPT > CuSO₄. Further tests of the combined effects of CuSO₄ and ZnPT revealed that mixing these biocides at their EC10 values produced greater toxicity than their individual effects. Although research concerning the synergistic effects of toxic mixtures is advancing, studies of epiphytic diatoms have been limited. Therefore, further research focused on toxicity and environmental effects among diatoms under various conditions is necessary.