Stocking of herbivorous fish to mitigate algal bloom in water bodies: A modeling approach

Algal bloom represents a pervasive environmental issue with far-reaching consequences for aquatic ecosystems and human well-beings on a global scale. Introducing herbivorous fish into lakes presents a hopeful strategy for alleviating the impacts of algal bloom, particularly in cases, where substantial reductions in nutrient input may not be practically achievable. In this work, we explore the impact of herbivorous fish on algal dynamics in three scenarios. In the first scenario, we introduce a mathematical model for the water ecosystem, where external sources actively maintain oxygen levels. The observed saddle–node and Hopf bifurcations offer insights into critical thresholds and regime transitions within the ecosystem. Further, we expand our analysis to second mathematical model, wherein oxygen levels are not sustained externally. We further broaden our investigation to assess the impact of intensified efforts on algae mitigation and how it affects the dynamics of the ecosystem within the water body. The proposed models demonstrate significant shifts in the interplay between herbivorous fish and algal biomass under various environmental conditions. We validate our analytical findings and highlight ecosystem resilience through numerical simulations.