Long-term population dynamics of dreissenids in lakes Michigan and Huron

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

Alexander Karatayev, Great Lakes Center at SUNY Buffalo State, [email protected]
Lyubov Burlakova, Great Lakes Center at SUNY Buffalo State , [email protected]
Knut Mehler, Great Lakes Center at SUNY Buffalo State, [email protected]
Ashley Elgin, NOAA Great Lakes Environmental Research Laboratory, [email protected]
Thomas Nalepa, Great Lakes Env. Research Lab, NOAA, [email protected]

Abstract

Although lakes Michigan and Huron have similar colonization history by dreissenids (both lakes were colonized by zebra mussels in 1989 and by quagga mussels in 1997), they exhibited different temporal and spatial dynamics and achieved different population sizes. Both lakes were initially dominated by zebra mussels and were replaced by quagga mussels after 6 – 8 years of coexistence. Recent surveys revealed a strong decline in the lake-wide population density in Lake Michigan, while in Lake Huron dreissenid density leveled off. Lake-wide dreissenid biomass, in contrast, have been increasing in both lakes during the whole period of observation (1994 – 2017). Although dreissenid population densities were always higher in Lake Michigan than in Lake Huron, the difference decreases from 6-fold in 2000 to 3-fold in 2017. In both lakes, quagga mussels in shallow (< 30 m) and intermediate (31 – 70 m) regions overshoot their carrying capacity and began to decline 12-15 years after first detection. This decline is accompanied by the shift of population maximums toward deeper regions, which likely results in overall slower population growth and production on a lake-wide basis.