So what is a representative network of MPAs?
Ecosystems are too big to protect in their entirety
If protected areas are to provide all their potential benefits, they must safeguard entire ecosystems - which can be very large and include different habitats.
Many marine species live in various habitats throughout their life cycle, and cover huge distances. Many adult fish found on coral reefs, for instance, spent their early years sheltered in a mangrove forest or seagrass meadow. And many open ocean fish migrate thousands of kilometres between their feeding and breeding grounds. The same is true for other marine species, from invertebrates to seabirds to whales.
For a single Marine Protected Area (MPA) to protect the full range of distribution for all species in one area, it would have to be huge - possibly even spanning an entire ocean!
Obviously, this is not practical, especially where an ecosystem crosses one or more national borders. Nor is it always desirable. For fisheries to benefit from MPAs, for example, they must be small enough to allow spillover of fish into adjacent fishing grounds.
So we create networks of MPAs within an ecosystem
To balance the needs of people and the marine environment, and to maximize protection benefits, the best solution is often a grouping of smaller MPAs protecting different habitats at various locations within the larger ecosystem.
These MPAs can have differing protection status and management structures, and even be in different countries. A group of protected areas like this is called an "ecologically representative network of MPAs", or a "representative network of MPAs" for short.
If well-designed, the location of MPAs in such a network would allow them to support each other by taking advantage of ocean currents, migration routes, and other natural ecological connections. This would help provide much-needed resilience against a range of threats. For example, if one MPA is damaged by a storm, oil spill, coral bleaching event, or other disaster, it could be re-colonized by ﬁsh and other species from an up-current MPA in the network. And by protecting multiple sites within the ecosystem, the overall damage caused by a disaster in one MPA is reduced.