Biodiversity generally refers to species richness (i.e.
number of species), but other definitions are also common.
It is critical that biodiversity is defined carefully as
it is sometimes considered synonymous with genetic diversity, habitat diversity, structural diversity, the diversity of functional groups (e.g. trophic groups of life
history stages) or even life history traits (e.g. feeding
type, growth forms, reproductive strategy, longevity).
Some definitions can be a proxy for species richness. For
example, species representation and abundance are known to vary among habitats. Habitat richness, therefore, can be especially relevant where the taxonomy of organisms in the various habitats is poorly known and there are concerns to protect species richness. A critical component of the zoning plan of the GBR (the Representative Areas Program, see Chapter 12) was partly based on the protection of different habitats and used these as surrogates to conserve species diversity as the biota on the GBR is poorly known apart from the corals and fish. In this chapter we focus on patterns of species richness at different spatial and temporal scales. We also note that descriptions of biodiversity and an understanding of processes influencing biodiversity (e.g. the impact of human activities) are critical for ecosystem management
