Bob points out in real terms what the studies (over 60) show and what Bill (it all depends) and others (including me) preach. Ponds and lakes are dynamic systems with many factors in play. Look at the ecosystem as a whole over time. Water quality , food , plants/plankton , different species and their interactions , potential competition and predation, spatial refuges/cover & habitat, direct and indirect effects through common predators and prey, and the influence of ontogenetic shifts in habitat and diet of the target and introduced species are all critical. These factors vary in large amounts among ponds and lakes and between years, making generalization difficult. I suggest a look back to Mark Cornwell’s recent PB mag article on the food web components and its complexity . These complexities are now interpreted using concepts like trophic cascades, … behavioral response to predation risk … , changes in behavior and reproductive strategies , and balancing between multiple stable states where the desired “balanced” state represents an unstable cusp between 2 undesirable stable states (stunted predator or prey populations with low body condition). You will see these concepts again in the next PB mag in an article on unintended consequences.

The names may be new but the concepts you know. The concept of a trophic cascade - that predators reduce the abundance of herbivores, allowing plants to flourish which focuses on the role of top-down forces (eg predation) and indirect effects in shaping ecological communities vs. trophodynamics, which explains the structure of communities using only bottom-up forces (eg resource limitation). IMO both are at work and must be understood as part of the whole ecosystem approach.