Final answer:
The populations of marsh snails and painted turtles will decrease due to the depletion of phytoplankton in the ecosystem.
Explanation:
The correct answer is: The populations of marsh snails and painted turtles will decrease.
When pollution depletes phytoplankton, the marsh snails, which feed on phytoplankton, will have less food available, leading to a decrease in their population. Subsequently, with fewer marsh snails to feed on, the population of painted turtles, which rely on marsh snails as a food source, will also decrease.
This scenario illustrates how disruptions in one part of an ecosystem can have cascading effects on other interconnected species within that ecosystem.
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