Coral Reefs: Biodiversity

Coral Reefs: A Reef Resilience Toolkit Module

R2 Home > Coral > Resilient Design > Representation > Biodiversity

Maintaining Resilient Ecosystems

Barrier reefs border shorelines and are separated from the adjacent land mass by a lagoon of open, deep water. Photo © S. Summerhays

Biodiversity is an essential component of maintaining healthy coral reefs. Healthy reef ecosystems with high biodiversity (a full complement of species and communities) are more likely to survive mass bleaching and other global stresses than less diverse systems. When multiple species occupy similar niches on the reef, disease, predation or other pressures affecting a single species are balanced by the presence of unaffected species that fill the ecological gap. But when biodiversity is low, those few species can be depleted by a single source of stress. Therefore, representation of all biodiversity is essential in MPA Network design.

The representation criteria of MPA design seeks to achieve protection of the full range of habitats and communities within the region, through adequate representation, replication, and resilience characteristics. Representative MPAs that are replicated in a well-connected network are more likely to lead to persistence and resilience in response to climate changes.

The patterns of coral distribution create the reef zonation. In general, the zones of a coral reef include a back reef, reef crest, and fore reef. Illustration courtesy NOAA CoRIS

Representation Classification

The first step in planning for adequate representation is to assess the habitat types and distribution in the region. Large scale biogeographical classifications of a region (i.e., ecoregion1) provide only a coarse description of the biodiversity in the area. Finer scale classifications (i.e., habitat level) may be required in order to adequately represent the range of biodiversity in the area. Representation at the habitat scale assumes that by representing all habitats, most elements of biodiversity (species, communities, etc.) will also be represented in the MPA network.

Left: The back reef zone is located on the sheltered side of the reef, closest to the shore. Reef flats are shallow water areas that extend from the shore to the reef crest. Because this zone is shallow, the back reef is often exposed at low tides.
Middle: The reef crest is located between the back reef and fore reef zones. The reef crest is exposed at low tide, and experiences the highest wave action.
Right: The oceanic side of the reef crest, farthest away from the shore is the fore reef zone. The fore reef zone slopes into deeper waters where light becomes a limiting factor for reef-building corals. Due to the limited wave action, this area maintains a high diversity of corals.
Photos left and right © ARVAM, middle © James Oliver (all reefbase.org)