To calculate the difference in coral cover between 1996 and 2002, you would need the specific coral cover percentages for those years from the graph you mentioned. Since I cannot see the graph, I cannot provide the exact difference.
However, to perform the calculation, you would subtract the coral cover percentage for 1996 from the coral cover percentage for 2002:
Difference = Coral Cover (2002) - Coral Cover (1996)
If you provide the actual coral cover values for those years, I can help you calculate the difference.