PRIMARY RESEARCH PAPER Impacts of invasion by Dreissena polymorpha (Pallas, 1771) on the performance of macroinvertebrate assessment tools for eutrophication pressure in lakes Javier Atalah • Mary Kelly-Quinn • Kenneth Irvine • Tasman P. Crowe Received: 9 March 2010 / Revised: 14 July 2010 / Accepted: 18 July 2010 Ó Springer Science+Business Media B.V. 2010 Abstract Aquatic ecosystems are experiencing increasing disturbance from multiple stressors caused by anthropogenic activities. The potential for multiple stressors to modify each others’ impacts is not well understood. Legislation such as the EU Water Frame- work Directive (WFD) requires the development of tools to assess human impacts in aquatic systems that incorporate ecological elements, such as macroinver- tebrates. Nutrient enrichment and invasive species are major threats to freshwater systems. The invasive zebra mussel Dreissena polymorpha is a conspicuous invader in freshwater aquatic systems in Europe and North America, and has been linked to drastic changes in macroinvertebrate communities and lake ecology. In 31 lake sites varying in nutrient pressure and in the presence or absence of D. polymorpha we tested three ecological quality assessment tools based on macroinvertebrate assemblages (% Sensitive Taxa to Total Phosphorus (TP), TP Score and Indicator Taxa Metric) and two basic ecological metrics. There were highly significant changes in macroinvertebrate diver- sity, structure, and composition associated with the invasion by D. polymorpha. While the three metrics performed consistently well in non-invaded systems, they lost explanatory power for eutrophication pres- sure in invaded systems. Our results suggest that metrics may need to be developed separately for invaded and non-invaded systems, and that the interaction between alien species and nutrient enrich- ment requires further investigation. Keywords Benthic Á Bioindicators Á Ecological classification Á Nutrient enrichment Á Water Framework Directive Á Zebra mussel Á Alien species Introduction The magnitude and intensity of anthropogenic stress- ors impacting aquatic ecosystems is generally increas- ing (Vitousek et al., 1997; Sala et al., 2000). Most ecosystems are not impacted by a single stressor, but by multiple stressors acting simultaneously (Strayer, 2010). While the effects of individual stressors at the species and ecosystems level have received considerable attention, there is still a lack of under- standing of their combined effects (Ormerod et al., Handling editor: P. No ˜ges J. Atalah Á M. Kelly-Quinn Á T. P. Crowe School of Biology and Environmental Science, Science Centre West, University College Dublin, Belfield, Dublin 4, Ireland J. Atalah (&) Ecological Consultancy Services Limited (EcoServe), B23 KCR Industrial State, Kimmage, Dublin 12, Ireland e-mail: jatalah@yahoo.com K. Irvine School of Natural Sciences, Zoology Building, Trinity College, University of Dublin, Dublin 2, Ireland 123 Hydrobiologia DOI 10.1007/s10750-010-0391-8