CHARACTERISING THE FOOD WEB DYNAMICS AND TROPHIC CASCADE EFFECTS IN TROPICAL RESERVOIRS

Abstract

Disruption to trophic links in the aquatic food webs may have profound effects on the stability and functioning of the ecosystem. My study aims to understand the patterns and drivers of trophic cascades in freshwater systems and how it affects the stability of ecosystems through: 1) a global meta-analysis, 2) mesocosm experiments, and 3) dynamic non-linear models. Results from my meta-analysis revealed strong trophic cascade effects in temperate systems and paucity of similar studies in the tropics. Following that, experiments conducted in a tropical reservoir revealed that trophic cascade impact is stronger than nutrient-mediated indirect effect. Finally, I illustrated how structural complexity and trophic redundancy confers greater food web stability and Bayesian Belief Network can be used to efficiently predict biomanipulation responses in food webs. Overall, this thesis contributes to the growing knowledge of trophic cascades and provides a holistic framework for ecosystem management.