Vincent Lyne & Peter Last (CSIRO Division of Marine Regionalisation)
There is a general recognition of the need to establish a scientific basis for a national framework to assess, conserve and manage Australia's marine biodiversiyt. A principal element of this framework is a spatioal assessment of the distribution of the faunal elements, their conservation value and status, and their grouping into bioregions.
We present here a provincial-scale bioregionalisation for the shelf region of the Australian EEZ. The regionalisations were derived from RAP (Rapid Assessment Procedure) analyses of the available fish distribution data. The dynamic evolution of the marihne biota and the extensive mixing of species assemblages is catered for by the introduction of biotones. Far from being "fuzzy" uncertainty regions surrounding boundaries, these are shown to be extensive and highly diverse bioregions containing species from a number of core provinces.
A provincial scale bioregionalisation was derived for the pelagic and demersal systems seperately. The pelagic bioregionalisation comprises 4 bioregions (two provinces and two zootones) of much more extensive spatial scale that the demersal bioregionalisation (17 bioregions, 9 provinces and 8 biotones).
The biological regionalisation indicates the expected pattern of higher species richness in the tropics relative to the cool temperate bioregions. However, when species are selected based on reliability and information content, the pattern is reversed showing a higher proportion of the temperate species are more reliable and of higher information content. Part of this is attributable to the lower reliability for the northern and north-western tropical species as well as the lower reliability of the north eastern (including the Great Barrier Reef), or the lack of ready assess to information. Collation and analysis of tropical information is a high priority for any future extensions and refinement of the current bioregionalisation.