Question

Rachel Carson wrote about the delicate balance of organisms in a food web. Snakeheads, a freshwater fish that is not normally found in the United States, was accidentally introduced to the Lake Eugene. As an adult, the Snakehead would feed on crustaceans, small fish, reptiles, and even small mammals. It would not have any predators in this environment. Considering the food web below how would this affect the ecosystem?

Answer 1

The snakehead could freely eat small fish and crustaceans, so that would remove/decrease the predator for zooplankton and phytoplankton. So zooplankton and phytoplankton population would increase while small fish and crustacean population would decrease. Now if small fish and crustacean population decreases, their predators would have lower food, so large fish pop. would decrease. If large fish pop. decreases, their predators will have less food and so the population of mammals will slightly drop, but not by much, since they can feed on zooplankton.

So ultimately, only the phytoplankton population would increase whilst everything everything else decreases.