Facilitative and competitive effects of Dreissena on benthos of Laurentian Great Lakes

Session: Mud, Macrofauna and Microbes: Benthic Organism-Abiotic Interactions at Varying Scales (1)

Lyubov Burlakova, Great Lakes Center at SUNY Buffalo State , [email protected]
Alexander Karatayev, Great Lakes Center at SUNY Buffalo State, [email protected]
Sonya Bayba, Great Lakes Center, [email protected]
Susan Daniel, Buffalo State College, Great Lakes Center, [email protected]
Knut Mehler, Great Lakes Center at SUNY Buffalo State, [email protected]
Anne Scofield, Purdue University, [email protected]
Elizabeth Hinchey Malloy, U.S. EPA GLNPO, [email protected]

Abstract

Exotic dreissenids are fundamentally changing the flow of energy and nutrients in Great Lakes ecosystems, affecting both the pelagic and benthic communities. Using data from the U.S. EPA Great Lakes National Program Office’s Biology Monitoring Program, the 2014-2015 Lakes Erie and lake Michigan Cooperative Science and Monitoring Initiative surveys and historic data, we detected taxonomic and functional changes in both littoral and profundal benthic communities invaded by dreissenids. In the littoral–benthic pathway, where detritus and energy fixed by benthic autotrophs are channeled to zoobenthos, dreissenids increased benthic diversity and abundance by creating novel habitat and providing trophic subsidies. In contrast, in pelagic–profundal pathway, where energy fixed by phytoplankton is channeled to zooplankton and profundal zoobenthos, dreissenids negatively impacted organisms by intercepting food. Yet the continuing expansion of quagga mussels offshore is increasing the abundance of profundal Oligochaeta by enhancing availability of limiting resources within dreissenid aggregations. To evaluate the relative importance of dreissenid facilitation vs competition, we are examining whether facilitative interactions are density-dependent, and how they vary in space, time, and along stress gradients.