Low concentrations of insecticide do not affect leopard frogs, but are lethal to zooplankton. Reduced zooplankton allows phytoplankton to increase, shading out periphyton (the vegetative food source for frog tadpoles), so tadpole growth is limited. Would a decrease in leopard frog population size following addition of the insecticide be due to top- down or bottom up control?

Top-down
Bottom-up

Bottom-up

Explanation:

The bottom approach is one that focuses on the lower orders systems to gives rise to the more complex systems and subsystems. In terms of the ecology, this principle refers to the lower or bottom nutrient levels and depends on the productivity and the primary producers that dominate the structures of the ecosystem. An example of this is the Bio-magnification that increases as we go higher in the food web chain. Thus the leopard frogs and development of the tadpoles are affected and impacted by the reduced zooplankton growth.