Synthetic surfactants for protecting cultured fish against toxicphytoplankton

摘要

Polyoxyethylene alkyl esters, which are surface-active agents, were chemically synthesized from fatty acids (C-12-C-18) on reaction with different moles of polyethylene oxides, and were tested for effectiveness against the toxic raphidophytes Chattonella marina (Subrahmanyan) Hara & Chihara and C. antiqua (Hada) One. The synthetic surfactants destroyed cultured cells from these two species. Although the synthetic surfactants also exhibited ichthyotoxicity, this was lowered by increasing the molarity of ethylene oxide (EO) in alkyl ester molecules. Young yellowtail, Seriola quinqueradiata Temminck & Schlegel, survived exposure to C. marina (5000-5500 cells mL(-1)) or C. antiqua (3000-3500 cells mL(-1)) cultures with the addition of 4-5 p.p.m. oleyl ester EO 14, but died within an hour without the addition of this surfactant.