Such cases provide overwhelming support for the economic, social, and political arguments to protect coral reefs. In other MPAs, management safeguards are in place, but pressures outside parks and reserves undermine the integrity of protected marine habitats. Johnston Atoll serves as one example of this problem. Probably among the earliest designations of a coral reef protected area, this site has been subjected to massive military development, high atmospheric nuclear testing, chemical waste disposal, and other threats. Elsewhere, external influences beyond the control of the management agencies undermine protected marine habitats.
Reefs are highly dynamic and open systems.
They cannot be fenced off and are dependent on the flow of currents carrying nutrients, circulating water and oxygen, and transporting larvae and other materials. But it is these same water movements that carry pollutants and sediments into protected areas, while overfishing upstream of a reef may cut off the vital supply of new recruits of coral and fish to the reef community. In this assessment, we found that reefs within many MPAs are under high potential threat. Protected areas can play a vital role, and act as flagships for the protection of coral reefs, but cannot be designated in isolation. The need for a more concerted and broadly based management regime, in many cases crossing national boundaries, will be essential for the ultimate protection of many reefs.