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Six decades of Lake Ontario ecological history according to benthos
Citation:
Burlakova, L., A. Karatayev, A. Hrycik, S. Daniel, K. Mehler, L. Rudstam, J. Watkins, R. Dermott, J. Scharold, A. Elgin, AND T. Nalepa. Six decades of Lake Ontario ecological history according to benthos. State of Lake Ontario Virtual Conference, Duluth, MN, March 09 - 11, 2021. https://doi.org/10.23645/epacomptox.14109437
Impact/Purpose:
This study analyzes six decades of changes in the benthic community of Lake Ontario to follow environmental problems and management decisions on the lake and to understand their effect on benthic community structure and abundance. Among the major issues discussed in the paper are cultural eutrophication in 1960s, water quality clean-up in 1970s, stocking of lake trout in 1980s and introduction of invasive species in 1990s. We found that the benthic community of Lake Ontario underwent significant transformations that can be described by three major periods: pre- and early Dreissena period, 1964-1990, zebra mussel dominance in 1990s, and quagga mussel dominance in 2000s. Although several analyses of long-term benthic community changes in some parts of the lake were published recently, to date there were no studies that have followed the dynamics of benthos since 1960s, nor were there attempts to expand these analyses to the entire lake-wide benthic community, and to analyze potential changes in taxonomic community structure. We hope the results of this study will be used binationally by lake managers, local and regional partners, and the general public.
Description:
The Laurentian Great Lakes have experienced multiple anthropogenic changes in the past century, including cultural eutrophication, phosphorus abatement initiatives, and the introduction of invasive species. Lake Ontario, the most downstream lake in the system, is considered to be among the most impaired. The benthos of Lake Ontario has been studied intensively in the last six decades and can provide insights into the impact of environmental changes over time. We used multivariate community analyses to examine temporal changes in community composition over the last 54 years, and to assess the major drivers of long-term changes in benthos. The benthic community of Lake Ontario underwent significant transformations that correspond with three major periods. The first period, termed the pre/early Dreissena period (1964-1990), was characterized by high densities of Diporeia, Sphaeriidae, and Tubificidae. During the next period defined by zebra mussel dominance (the 1990s) the same groups were still prevalent, but at altered densities. In the most recent period (2000s to present), which is characterized by the dominance and proliferation of quagga mussels deeper into the lake, the community has changed dramatically: Diporeia almost completely disappeared, Sphaeriidae have greatly declined, and densities of quagga mussels, Oligochaeta and Chironomidae have increased. The introduction of invasive dreissenids has changed the Lake Ontario benthic community, historically dominated by Diporeia, Oligochaeta and Sphaeriidae, to a community dominated by quagga mussels and Oligochaeta. Dreissenids, especially the quagga mussel, were the major drivers of these changes over the last half century. The views expressed in this abstract are those of the authors and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.
