Yes. Isolated MPAs typically tend to protect one specific feature or set of species. There are many ideas for doing a network. One of them is having complementarity, which means that we protect a bit of everything. One MPA may protect rockfish, but another one may protect corals and so on, so through the network we protect a bit of everything.
Another idea is that the network can bring benefits from one MPA to another. A lot of scientists are looking now at larval dispersion. To reproduce, fish create larvae. Those larvae go through the currents somewhere, settle, and then grow. It's an effort to look at how those species are arranged, and to assess whether one specific part of the network can actually benefit other parts of the network. That's something that has been studied in Australia a fair bit.