Do you think a population besides the moon jellies’ consumer population (sea turtles) and resource population (zooplankton) could have caused the moon jelly population to increase in size?

I didn't quite understand your question, but the moon jelly population will increase if there are either more zooplankton or less sea turtles.

More zooplankton means more food => higher population

Less sea turtles means that the moon jelly will be lest often consumed => higher population

  distance on the y-axis and time on the x-axis.

explanation:

the instantaneous velocity = change in position/time taken

the slope of the graph should give instantaneous velocity.

  slope of a graph = change in value of y -axis / change in values of x -axis

  comparing both the equations

    change in value of y -axis = change in position

  change in values of x -axis = time taken

so position values should be on the y axis and time values should be on the x axis.

distance on the y-axis and time on the x-axis.