How do calcareous algae contribute to coral reef structure?

Calcareous algae play a vital role in the development and maintenance of coral reef structures. While stony corals typically provide the primary structural framework, calcareous algae serve as essential binding and cementing agents that hold the reef complex together through their sheetlike growth.1

Their contribution is particularly significant in high-energy environments; in areas such as the central Pacific where surf conditions are very strong, calcareous algae may be more important than corals in forming the reef structure in the roughest locations. Additionally, various algae contribute to the reef by trapping and stabilizing sediment, which then accretes to the overall reef complex. By binding together the various shelly and calcareous fragments that fall into gaps between corals, these algae ensure the structural integrity of the reef.12