The contribution of fatty acid amides to Prymnesium parvum Carter toxicity

► We have evaluated toxicity of fatty acid amides identified from Prymnesium parvum. ► Fatty acid amides are hemolytic and cytoxic against mammalian and fish cells. ► At least one of these compounds accumulates to toxic levels in the environment. ► Toxicity of fatty acid amides is increased by divalent cations and high pH. ► Abiotic factors can increase toxicity of compounds after they are released.