Twenty five years of changes in Dreissena spp. populations in Lake Erie Alexander Y. Karatayev a, ⁎, Lyubov E. Burlakova a,b,1 , Christopher Pennuto a,c,2 , Jan Ciborowski d,e,3 , Vadim A. Karatayev f , Paul Juette a,c , Mark Clapsadl a a Great Lakes Center, SUNY Buffalo State, Buffalo, NY, USA b The Research Foundation of The State University of New York, SUNY Buffalo State, Office of Sponsored Programs, Buffalo, NY, USA c Biology Department, SUNY Buffalo State, Buffalo, NY, USA d Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada e Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada f Office of Undergraduate Biology, 216 Stimson Hall, Cornell University, Ithaca, NY 14853, USA abstract article info Article history: Received 3 April 2013 Accepted 9 April 2014 Available online xxxx Communicated by Thomas Bridgeman Index words: Dreissena polymorpha Dreissena rostriformis bugensis Density Biomass Exotic species Great Lakes Lake Erie has the longest history of colonization by both Dreissena polymorpha and Dreissena rostriformis bugensis in North America and is therefore optimal for the study of long-term dynamics of dreissenid species. In addition, the morphometry of Lake Erie basins varies dramatically from the shallow western to the deep eastern basin, making this waterbody a convenient model to investigate patterns of Dreissena distribution, as well as interspe- cies interactions among dreissenids. We compare our data on the distribution, density and wet biomass of both dreissenid species in Lake Erie collected in 2009 and 2011–2012 with previous data. We found that Dreissena spp. distribution in Lake Erie varied depending on the time since the initial invasion, collection depth, and lake basin. In 2009–2012, zebra mussels were smaller than in 1992 and were consistently smaller than quagga mussels. Dur- ing 2009–2012, quagga mussels were found at all depths and in all basins, while zebra mussels were common in the western basin only, and in the central and eastern basins were limited to shallow depths, resulting in an al- most complete replacement of D. polymorpha with D. rostriformis bugensis. In the shallowest western basin of Lake Erie, zebra mussels represented N 30% of the combined dreissenid density even after more than 20 years of coexistence, providing strong evidence that, even in lakes as large as Lake Erie (or at least its western basin), D. polymorpha may sustain a significant presence for decades without being displaced by quagga mussels. © 2014 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Introduction The introduction of the zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis) into North America in the 1980s resulted in significant negative economic and ecological im- pacts (reviewed in Hecky et al., 2004; Karatayev et al., 1997, 2002, 2007; Nalepa and Schloesser, 1993; O'Neill, 2008; Vanderploeg et al., 2002). The ecological impacts of both species are associated with their role as ecosystem engineers, and the magnitude of their effects is deter- mined by the population density in a given waterbody (Karatayev et al., 2002). However, populations of Dreissena species do not stabilize and can vary widely over time (Burlakova et al., 2006; Karatayev et al., 1997, 2002, 2011; Nalepa et al., 2010; Ramcharan et al., 1992; Strayer and Malcom, 2006). In addition, different Dreissena species have different spatial distributions in a waterbody. Zebra mussels require hard substrate for their attachment and are usually more abundant in the littoral zones, avoiding silt in deep areas, whereas quagga mussels may effectively colonize soft substrates in the profundal zone (reviewed in Karatayev et al., 2011). When both species colonize the same waterbody, D. rostriformis bugensis usually establish high densities and outcompete D. polymorpha in deep lakes with large profundal zones while zebra mussels may be abundant and coexist with quagga mussels in shallow lakes and rivers (reviewed in Karatayev et al., 2011; Zhulidov et al., 2010). Moreover, different Dreissena species have different popu- lation dynamics, and the estimated lag time between initial introduc- tion and maximal population size in a given waterbody is 5 times shorter for D. polymorpha than for D. rostriformis bugensis (Karatayev et al., 2011). As a result, Dreissena species' ecological impacts will de- pend on their total population density, time since the initial invasion, species composition, and the morphometry of an invaded waterbody. Therefore, up-to-date information on these parameters is critically im- portant for predicting the ecological impacts of Dreissena. Lake Erie has the longest history of colonization by both Dreissena species in North America. According to Carlton (2008), the first D. polymorpha was found in this lake in 1986, and the first D. rostriformis Journal of Great Lakes Research xxx (2014) xxx–xxx ⁎ Corresponding author. Tel.: +1 716 878 5432. E-mail addresses: karataay@buffalostate.edu (A.Y. Karatayev), burlakle@buffalostate.edu (L.E. Burlakova), pennutcm@buffalostate.edu (C. Pennuto), cibor@uwindsor.ca (J. Ciborowski), vak32@cornell.edu (V.A. Karatayev). 1 Tel.: +1 716 878 4504. 2 Tel.: +1 716 878 4105. 3 Tel.: +1 519 253 3000. JGLR-00728; No. of pages: 10; 4C: http://dx.doi.org/10.1016/j.jglr.2014.04.010 0380-1330/© 2014 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Great Lakes Research journal homepage: www.elsevier.com/locate/jglr Please cite this article as: Karatayev, A.Y., et al., Twenty five years of changes in Dreissena spp. populations in Lake Erie, J. Great Lakes Res. (2014), http://dx.doi.org/10.1016/j.jglr.2014.04.010