The contribution of fatty acid amides to Prymnesium parvum Carter toxicity

It is well known that toxic blooms of Prymnesium parvum result in widespread fish mortalities. An assemblage of fatty acid amides (FAAs) has been shown to be toxic metabolites of P. parvum. Several compounds and compound classes have been implicated in P. parvum toxicity, but unlike FAAs, thus far none have been shown to accumulate to lethal levels at ichthyotoxic bloom events. The purpose of this study is to characterize the hemolytic activity, cytotoxicity, and ichthyotoxicity of the fatty acid amides identified from P. parvum using mammalian red blood cells, mouse neuroblastoma cells, and rainbow trout gill cells. We also investigate the effect of abiotic factors (divalent cations and pH) on fatty acid amide toxicity. Samples from P. parvum bloom events with fish kills were analyzed in order to demonstrate that fatty acid amides are found in lethal levels at fish kills. Hemolytic and cytoxicity assays were completed with the introduction of abiotic factors to assess fatty acid amides toxicity. Our results show that fatty acid amides are detected in toxicologically significant quantities in samples from at least one fish kill event. We also show that the toxicity of oleamide and linoleamide in cell culture is increased in the presence of divalent cations and increasing pH, demonstrating that multiple abiotic factors affect the toxicity of fatty acid amides. Fatty acid amides possess the hemolytic and cytotoxic properties previously attributed to P. parvum toxins throughout history. After fatty acid amides have been released into the environment, multiple abiotic factors can increase their toxicity. Published by Elsevier B.V.