Effects of organic wastewater contaminants on aquatic macroinvertebrates: Implications for future toxicity testing



Journal Title

Journal ISSN

Volume Title



Organic wastewater contaminants (OWCs), including many known endocrine disruptors (EDs) and pharmaceuticals, have been detected in North American surface waters and are cause for toxicological concern. OWCs are not meant to be targeted or applied to the environment, so they haven’t been scrutinized or subjected to mandated testing regarding possible adverse environmental effects. OWCs of concern include EDs which have been shown to exert sublethal effects at environmentally relevant exposure concentrations in a wide range of vertebrate test species. The observed sublethal effects may, in turn, have effects on the fitness of exposed populations and potential community level consequences. Unfortunately, fewer studies have been aimed at understanding the effects of endocrine disruptors on invertebrates. In many systems invertebrates are important components serving a variety of ecosystem roles. Mollusks, particularly, have strong impacts on primary producers, can be the primary food source for small carnivores and can dominate macroinvertebrate biomass. Crustaceans are another class of important freshwater invertebrates. Daphnia, for example, are a frequently used test species in aquatic toxicology; they have short generation times and play a significant role in freshwater communities. My objective was to evaluate the effects of commonly found OWCs on life history traits in the freshwater gastropod, Physa pomilia, and the freshwater zooplankton, Daphnia magna. To address this objective, two model organisms were monitored after exposure to 17-α ethynylestradiol (EE2) and Fluoxetine. 17-α ethynylestradiol (EE2) is a synthetic hormone found in many forms of birth control { running header} Texas Tech University, Tamara O. Luna, August 2012 v and fluoxetine is selective serotonin reuptake inhibitor used as an antidepressant. I quantified total egg masses laid, total eggs laid, hatching success, body size, time to first reproduction, and mortality. In snails, I found for EE2 that time at first reproduction, hatching success, egg mass and total egg production all showed treatment-related effects and that the second generation showed a stronger adverse response than the first generation. In the fluoxetine experiments we found that total egg masses laid per snail, total eggs laid per snail, hatching success, size, time to first reproduction, and mortality were affected but the observed effects were mainly in the second generation. Furthermore, the second-generation snails exposed to fluoxetine did not display a typical, monotonic dose response which has similarly been observed by others and suggests endocrine disrupting activity. In the Daphnia study, EE2 decreased neonates per brood at the lowest concentration. Fluoxetine decreased total broods per Daphnia and time to death at the highest tested concentration. The mixture showed effects that both chemicals elicited separately; neonates per brood, total brood and time to death were all decreased in the highest mixture concentrations. Overall, the results provide additional insight into the effects of OWCs on important freshwater invertebrates and point to the importance of exposure duration in the design and implementation of toxicity studies.



17-α ethynylestradiol, Endocrine disruptor, Fluoxetine, Pharmacueticals and personal care products