When most people mention reefs, they usually mean coral reefs, without realising that reefs can be extensive in cooler (temperate) waters.
Temperate reefs are highly productive and highly diverse (much more so than the more famous tropical reefs like the Great Barrier Reef), yet until quite recently, very little attention has been paid to them.
Reef Watch Temperate Reef Fact Sheets:
Temperate reefs - mobile invertebrates
Temperate reefs - mobile invertebrates 2
Temperate reefs - stationary invertebrates
Temperate reefs - stationary invertebrates 2