Toxicological study for phenol using germling growth of the brown macroalga Sargassum horneri

Abstract

Marine macroalgae are important for maintaining ecosystems in coastal areas. However, to our knowledge, only a few studies of marine macroalgae have developed protocols for assessing the toxic effects of growth inhibitors typically found in industrial wastewaters. Sargassum horneri, a large brown macroalga commonly found in seaweed beds in coastal Japan, can be easily collected, and its fertilized eggs can be preserved for approximately 170 days. Therefore, the present study evaluated the possibility of developing a seaweed bioassay using the germling growth of S. horneri to obtain toxicological data for phenol. The addition of phenol to culture media clearly inhibited the germling growth of S. horneri. The 14-day EC 50 value on the basis of the specific growth rate was 58 mg phenol L −1 , while the 21-day EC 50 value on the basis of the thallus area was 36 mg phenol L −1. Furthermore, the no-observed-effect concentration was estimated to be 20 mg phenol L −1. Renewal of culture medium did not significantly affect germling growth of S. horneri during our 21 days of culturing. S. horneri appeared to be as sensitive to phenol as other marine macroalgae reported in the previous studies. Therefore, we consider that S. horneri is one of the appropriate candidates of macroalgae for toxicity testing.