Citation:

Karatayev, A., L. Burlakova, K. Mehler, A. Elgin, L. Rudstam, J. Watkins, AND M. Wick. Dreissena in Lake Ontario 30 years post-invasion. JOURNAL OF GREAT LAKES RESEARCH. International Association for Great Lakes Research, Ann Arbor, MI, 48(2):264-273, (2022). https://doi.org/10.1016/j.jglr.2020.11.010

Impact/Purpose:

This paper reviews data from three decades of changes in dreissenid populations and predation by round goby in Lake Ontario. A longitudinal analysis of Lake Ontario Dreissena populations has not been done previously. The paper advances our understanding of the ecological effects of Dreissena in Lake Ontario. Ongoing biomass increases suggest that ecological impacts are still increasing also.

Description:

We examined three decades of changes in dreissenid populations in Lake Ontario and predation by round goby (Neogobius melanostomus). Dreissenids (almost exclusively quagga mussels, Dreissena rostriformis bugensis) peaked in 2003, 13 years after arrival, and then declined at depths <90 m but continued to increase deeper through 2018. Lake-wide density also increased from 2008 to 2018 along with average mussel lengths and lake-wide biomass, which reached an all-time high in 2018 (25.2 ± 3.3 g AFTDW/m2). Round goby densities were estimated at 4.2 fish/m2 using videography at 10 to 35 m depth range in 2018. This density should impact mussel populations based on feeding rates, as indicated in the literature. While the abundance of 0–5 mm mussels appears to be high in all three years with measured length distributions (2008, 2013, 2018), the abundance of 5 to 12 mm dreissenids, the size range most commonly consumed by round goby, was low except at >90 m depths. Although the size distributions indicate that round goby is affecting mussel recruitment, we did not find a decline in dreissenid density in the nearshore and mid-depth ranges where goby have been abundant since 2005. The lake-wide densities and biomass of quagga mussels have increased over time, due to both the growth of individual mussels in the shallower depths, and a continuing increase in density at >90 m. Thus, the ecological effects of quagga mussels in Lake Ontario are likely to continue into the foreseeable future.

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