Effects of quagga mussels and Hemimysis anomala on Lake Michigan plankton and benthic algae

Session: Invasive Species (4)

Scott McNaught, Central Michigan University, [email protected]
Katherine Grosh, Carleton College, [email protected]

Abstract

Since the early 1800s, ballast water has introduced hundreds of invasive species into the Great Lakes, causing widespread ecologic and economic turmoil.  Dreissena bugensis (Quagga mussels) and Hemimysis anomola (Bloody Red Shrimp) are two of these invasive species from the Ponto-Caspian region that have disrupted the lower food web of the Great Lakes.  We conducted a 21-day mesocosm experiment on Beaver Island, MI, to determine the individual and combined effects of these invaders on zooplankton, phytoplankton, and benthic algae. Quagga mussels and Hemimysis negatively impacted zooplankton and phytoplankton, and quagga mussels promoted growth of benthic algae.  Together, both invasive species had mixed effects on plankton, potentially because adult Hemimysis had lower survival rates in tanks with quagga mussels.  Competition from quagga mussels may reduce the impact of Hemimysis on the lower food web, and potentially create less-detrimental effects on the ecosystem.