Date of Award
Level of Access
Master of Science (MS)
Ecology and Environmental Sciences
Second Committee Member
Third Committee Member
Introduction and removal of strictly planktivorous fish in lakes can alter plankton communities via cascading interactions in food webs. Less is known about the large-scale and long-term effects of introduction of fish with more generalist feeding habits. Both whole-lake biomanipulation and paleolimnological approaches were used to analyze the responses of plankton communities to the introduction of white perch (Morone americana), a fish that often numerically dominates fish assemblages and switches from strict planktivory to omnivory during ontogeny. In a lake-scale removal of perch from a eutrophic lake, zooplankton body size decreased but there was no cascading effect on the algal community due to the role of "bottom-up" drivers. Paleolimnological analyses of oligotrophic lakes demonstrate an increase in cladoceran body size, inferred from fossil ephippia, and a decrease in algal production, inferred from fossil pigments, following white perch introduction. These results are counter to predictions from a top-down trophic cascade as may be expected from the introduction of strictly planktivorous fish. This study highlights the importance of trophic interactions in structuring lake food webs and the utility of combining approaches that span spatial and temporal scales to investigate complex trophic interactions in lakes.
Ditzler, Kristin Elizabeth, "Effects of White Perch Introductions on Food Web Dynamics: Combining Paleolimnological and Whole-Lake Biomanipulation Approaches" (2010). Electronic Theses and Dissertations. 1140.