Eighteen freshwater mussels (Elliptio dilatata) were randomly assigned to three groups of six each. One group was placed in water from the river where the mussels were collected, one group was placed in deionized water, and one group was placed in a solution of 0.5 millimoles per liter (mM) of sodium sulfate. At the end of a specified time period, blood (hemolymph) was collected from each mussel and potassium levels were determined. Required:
Do the treatments affect blood potassium levels (mM K+)?