Integrated Marine and Coastal Regionalisation of Australia (IMCRA) v4.0 - Provincial Bioregions

Brief description

A regionalisation of Australian waters (excluding waters adjacent to the Territory of Heard Island and McDonald Islands, and waters adjacent to the Australian Antarctic Territory) derived from deep-water demersal fish assemblages. A total of 41 onshelf and offshelf provincial bioregions were identified for IMCRA v4.0.

Onshelf provincial bioregions are based on the 17 IMCRA v3.3 demersal provinces and biotones identified in 1997.

Offshelf provincial bioregions were defined in 2004 as part of a program run by Geoscience Australia, CSIRO Marine Research and the National Oceans Office. They represent units that contain broad patterns in biodiversity, as represented by deep-water demersal fish assemblages, based on the assumption that the demersal fish distributions are a surrogate of marine faunal distributions. Below 2,000 m water depth, the boundaries of the benthic provincial bioregions are defined solely by the NMB (National Marine Bioregionalisation) geomorphic features data set. A total of 24 offshelf benthic provincial bioregions were defined on this basis, including 15 core bioregions representing areas of endemism, and 9 transition zones representing areas of faunal mixing.

For IMCRA v4.0 the coastline was replaced with the national 100k coastline to provide greater consistency. The Australian EEZ limit was sourced from AMB v2. Based on a decision by the Bioregionalisation Working Group, the shelf break from IMCRA v3.3 was largely retained, although in some instances the shelf break from the NMB (National Marine Bioregionalisation) provincial bioregions was used.

Lineage

Maintenance and Update Frequency: asNeeded

Statement: The benthic Provincial Bioregions were defined in 2004 as part of a program run by Geoscience Australia, CSIRO Marine Research and the National Oceans Office to create a spatial inventory of large-scale benthic biogeographical regions for Australias Exclusive Economic Zone. The Provincial Bioregions were defined by the regional structure in demersal fishes as represented by a one-dimensional made up of 281 nodes that correspond to the 500 m isobath around the Australian mainland. The analysis of the demersal fish data was undertaken by CSIRO Marine Research (Last et al., 2004). None of the offshore island territories were included in this assessment and each island territory was considered a separate bioregion. The boundaries of the Provincial Bioregions below 2,000 m water depth were defined solely by the geomorphic features, which were defined by the International Hydrographic Office (IHO, 2002), and were identified using a 250 m spatial resolution bathymetry model with reference to previously published geological studies. In the analysis of the demersal fish data, the boundaries between the Provincial Bioregions were defined by a Jaccard Analysis of the distributions. The final boundaries were drawn by eye around the boundaries of geomorphic features by a panel of scientific experts at a series of workshops with reference to previous studies. When completed, the boundaries defined the separate polygons and they were stored as an ArcGIS shape file. Care was taken to include as much biological information as possible when positioning the boundaries, particularly in shallow water (500 m).

Notes

Credit
Integrated Marine and Coastal Regionalisation of Australia (IMCRA) v4.0 - Provincial Bioregions. (c) Commonwealth of Australia, Australian Government Department of the Environment and Heritage. (2006).