Bioregionalisation for the SW Pacific and Indian oceans

Lead: Piers Dunstan (CSIRO)


Biogeographic regionalisation – or bioregionalisation for short – is a process by which the physical and biological variability in the environment is analysed, classified and mapped into spatial units, each with distinct biological, ecological and physical properties.  The process simplifies the complex spatial organisation in nature (e.g., habitats) and represents it on a map to improve understanding and inform decision making.  Biogeographic maps of naturally defined and distinct provinces are an essential tool for the sustainable use and conservation of marine biodiversity (e.g., for developing an ecologically representative and coherent network of marine protected areas).

As a step towards ensuring the connectivity, sustainable use and conservation of marine biodiversity, bioregionalisation exercises for the western South Pacific Ocean and the Indian Ocean have been conducted.  This approach builds upon that developed and established by the Australian national marine bioregionalisation process, undertaken by CSIRO.  By collating and integrating available physical and biological information in a systematic manner, a set of biogeographic provinces has been identified that reflects habitat diversity, biological diversity and the interaction between the two.  These outputs are compatible with those from similar exercises around the world.

Stakeholders from the region, including data holders, marine resource users, public and private sector environmental agencies, and relevant national and international governance authorities, have been included at various stages in the process, to ensure that the final outcome of the work is a set of appropriate, inclusive, integrated and transparent management tools for the region.


  • To develop a bioregionalisation for the western South Pacific Ocean and the Indian Ocean.
  • To promote connectivity and ecological coherence in spatial management.
The process of developing bioregionalisations


A stepwise approach to the completion of this work includes the following activities:

  • Identification, acquisition and collation of physical and biological datasets available in the region of interest, thereby rationalising their format for inclusion in the analysis.
  • Application and refinement of existing methods, starting with the processing of physical datasets to produce a physical regionalisation and production of draft bioregionalisations for selected taxa.
  • Organisation of regional international workshops to involve regional data holders, the scientific community, industry and regional governments in the development of bioregionalisations for the Indian and western South Pacific Oceans.
  • Verification of the boundaries generated by the bioregionalisation process, followed by engagement with regional, national and international authorities to ensure that the results and limitations of the bioregionalisation exercise are understood and used to optimise the effectiveness of local, national and regional marine spatial management plan.


Results to date

Once the mathematical models used to perform biogeographical analyses were selected and refined, physical regionalisations of the Indian Ocean and of the southern Pacific Ocean were completed. These form the canvas on which to place species observation data, building up information on species’ habitat preferences and the extent of their distribution.

As a result of these activities, in the Indian Ocean, 72 benthic and 14 pelagic bioregions have been identified, and in the southern Pacific Ocean, 35 benthic and 16 pelagic bioregions have been identified.  Each of these bioregions has been described, mapped, and a qualitative ecosystem model that identifies the key pressures acting on it has been created.

Descriptions of all the bioregions identified are available in two reports (left – click captions to download reports).

All of these outputs have undergone final checks by comparison with direct observation of their predictions in the field.  Now validated, they are finalised and available for dissemination and application across the region. Results are already being used and in a handful of localised applications.

Publications that have emerged from this work include:

  • Bioregions in Marine Environments: Combining Biological and Environmental Data for Management and Scientific Understanding, by S Woolley and colleagues, in BioScience, January 2020, Vol. 70 No. 1 (download).
  • Contrasting Processes Drive Ophiuroid Phylodiversity across Shallow and Deep Seafloor, by T D O’Hara and colleagues, in Nature, January 2019, Vol. 565 No. 7741 (download).


There are many spheres of science, industry and civil society in which a state-of-the-art bioregionalisation would be useful.  For example, the resultant maps from this work can inform the placement of marine protected areas, as well as the choice of spatial or temporal management measures on fishing, mining, marine traffic or industrial discharge.  Understanding the interacting characteristics of different bioregions allows the tailoring of management practices to ensure sustainable use and conservation of biodiversity across each of the ocean basins.  These examples represent and embody the CBD’s objectives of conservation, sustainable use and fair sharing of the benefits arising from the utilisation of biodiversity and associated natural resources.