To assess whether different concentrations of dissolved organic matter (DOM) rich in humic substances (HS) affect growth rates, reproduction and fatty acids (FA) composition of Daphnia pulex under bright light, we performed microcosms controlled laboratory trials. Experiments were run using two microalgae as food source, Cryptomonas erosa and Scenedesmus acutus at four DOM additions (0 mg C L −1 , 15 mg C L −1 , 30 mg C L −1 ,...