Answer:
Some organisms are affected.
Step-by-step explanation:
If the pH of the pond dropped to 5.5, some of the organisms living in the pond affected because most of the organisms present in the graph lives in highly acidic and slightly acidic water so when the pH is dropped to 5.5, only frog and perch are greatly affected and decrease in its population occurs while the other organisms are not greatly affected with the change of this pH.