Ecosystem Change Leads to Reduced Growth of Lake Whitefish
Ann Arbor, MI — Growth and condition of lake whitefish decreased in Lake Ontario following the establishment of zebra mussels and related quagga mussels (dreissenid mussels) in the early 1990s. Similar changes were not as apparent in lake whitefish from Lake Erie, even though dreissenid mussels had also established there.
Researchers from the University of Windsor and the Ontario Ministry of Natural Resources used long-term time series data to investigate patterns of growth and condition, along with diet analysis and energy content of lake whitefish from both lakes. Diets of lake whitefish from Lake Erie are more diverse than those from Lake Ontario. Lake whitefish from Lake Erie also had higher energy content and greater reproductive output (gonad weight as a proportion of body weight).
Most of the diet of lake whitefish in Lake Erie and Ontario is made up of small invertebrates that live on the bottom of lakes, where there have been dramatic changes since dreissenid mussels were first detected. The sudden disappearance of the lipid-rich invertebrate Diporeia from eastern Lake Ontario resulted in the loss of an important prey item from adult whitefish diets. Decreased growth and condition of lake whitefish from Lake Ontario are likely due to decreased energy content of diets compared to pre-dreissenid mussel conditions, and possibly lower availability of benthic prey compared to Lake Erie.
Comparing populations that have responded differently to ecosystem change helps us to better understand ways that changes can be manifested at different trophic levels (or levels of the food web).
Original Publication Information
Results of this study, "Comparison of Lake Whitefish (Coregonus clupeaformis) Growth, Condition, and Energy Density between Lakes Erie and Ontario," are reported by Chelsey E. Lumb, Timothy B. Johnson, H. Andrew Cook and James A. Hoyle in the latest issue (Volume 33, No. 2, pp. 314-325) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, contact Tim Johnson, Ontario Ministry of Natural Resources, Glenora Fisheries Station, RR #4, Picton, ON, K0K 2T0, Canada; tim.johnson@mnr.gov.on.ca, (613) 476-7718.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, Environment Canada, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; jglr@ec.gc.ca; (306) 975-5310.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.