Some 45–53% of the world’s shallow coral reefs have been destroyed or severely damaged (core case study). A number of factors have played a role in this serious loss of aquatic biodiversity, including...

Some 45–53% of the world’s shallow coral reefs have been destroyed or severely damaged (core case study). A number of factors have played a role in this serious loss of aquatic biodiversity, including ocean warming, sediment from coastal soil erosion, excessive algal growth from fertilizer runoff, coral bleaching, rising sea levels, ocean acidification, overfishing, and damage from hurricanes.

In 2005 scientists Nadia Bood, Melanie McField, and Rich Aronson conducted research to evaluate the recovery of coral reefs in Belize from the combined effects of mass bleaching and Hurricane Mitch in 1998. Some of these

reefs are in protected waters where no fishing is allowed. The researchers speculated that reefs in waters where no fishing is allowed should recover faster than reefs in waters where fishing is allowed. The graph to the left shows some of the data they collected from three highly protected (unfished) sites and three unprotected (fished) sites to evaluate their hypothesis. Study this graph and then answer the following questions.

By about what percentage did the mean coral cover drop in the protected (unfished) reefs between 1997 and 2005?