Composition of Algal Cup Reefs

Algal cup reefs appear to be massive limestone with a sparse cover of organisms. However, closer examination reveals that the reefs are built by intergrowth of crustose coralline algae and encrusting Millepora spp. in which numerous vermetid gastropods are imbedded.

The framework of these algal cup reefs has extensive voids: large and intermediate size, growth framework and shelter pores;borings of bivalves and sponges; and both intra- and inter-particle pores. A variety of fragile and sessile organisms inhabit these pores: encrusting foraminifer, Homotrema rubrum, is the most abundant attached organism; The tests of a variety of benthic foraminifera and ostracods are common; branched coralline algae, barnacles, bivalves, ahermatypic coral, bryozoan and burrowing crustaceans occur in varying abundance.