The contractile vacuole will become less active. This is because a hypotonic environment sees water constantly entering the cell due to osmosis, which must then be expelled by the contractile vacuole. Moving to an isotonic environment will stop the flow and lessen the need for contractile vacuole activity as water moves across the membrane in both directions evenly.
Work Step by Step
To understand this, review how osmosis works and the role of the contractile vacuole in regulating water contents in cells such as Paramecium.