Thomas R. Renicker Claudia E. Tausz Jade L. Young Jennifer C. Thomason Zachary L. Wolf Amber L. Russell Mac A. Cherry Kyle C. Scotese Dawn T. Koenig John R. Beaver 2018 <p>We describe swarming behavior in the invasive cladoceran <i>Daphnia lumholtzi</i> Sars, 1885 in a Kentucky, USA, reservoir during winter 2017. The taxon is a highly successful tropical invader and has spread throughout the lower latitude systems in the USA since its discovery in 1991. Other than a few isolated reports, the abundance of <i>D. lumholtzi</i> is often &lt;1 organism&nbsp;L^-1. Previous studies indicate that <i>D. lumholtzi</i> is a largely thermophilic species often peaking in abundance in late summer after native daphnids are gone from the water column of lakes and reservoirs. Prior to our study, there have been no published reports of swarming behavior by this species. We document the occurrence of massive swarms (&gt;10,000 organisms L^-1) of sexually reproducing females of this exotic cladoceran at water column temperatures &lt;10°C.</p> application/pdf 10.3391/bir.2018.7.1.06 en REABIC Winter swarming behavior by the exotic cladoceran Daphnia lumholtzi Sars, 1885 in a Kentucky (USA) reservoir article