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Seascapes of the Australian margin and adjacent sea floor: methodology and results

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Whiteway, T and Heap, A and Lucieer, VL and Hinde, A and Ruddick, R and Harris, PT (2007) Seascapes of the Australian margin and adjacent sea floor: methodology and results. Technical Report. GeoScience Australia, Canberra, ACT.

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Abstract

Geoscience Australia has undertaken a classification of biophysical datasets to create seabed
habitat maps (termed ‘seascapes’) for the Australian margin and adjacent sea floor. Seascapes
describe a layer of ecologically meaningful biophysical properties that spatially represents
potential seabed habitats. Each seascape area corresponds to a region of the seabed that
contains similar biophysical properties and, by association, potential habitats and
communities. The procedure adopted is inspired by the shelf classification applied in eastern
Canada where physical properties (sediment type, physiography, bed roughness, wave and
current regime) were used to define ecologically meaningful habitats on the Scotian Shelf.
Creating seascapes as proxies for benthic marine biological communities using biophysical
data is required because it is impossible to count and map the distribution of every organism
in the ocean.
This report describes the iterative methods used to create the seascapes, including a
detailed appendix documenting the different datasets used in each planning zone. Creating
the seascapes is necessarily an iterative process whereby the available datasets are integrated
in different combinations, or added as they become available, using the ERMapper™
unsupervised, crisp ISOclass classification program. In each classification only biophysical
properties that have consistent and definable relationships with the benthic biota and are
known in sufficient detail across Australia’s entire marine region are used to create the
seascapes. An initial validation of the classification technique has been undertaken on a
subset of the data for the shelf surrounding Tasmania using an alternative unsupervised
fuzzy classification. Results of this validation indicate that the unsupervised classification
methodology provides consistent and reliable classes for defining the seascapes.
Finally, a quantitative method designed to determine where the greatest seabed
heterogeneity occurs to assist with the selection of potential sites for Marine Protected Areas
was trialled on the final seascapes. This Focal Variety method conducted in ArcGIS simply
counts up the number of seascape types within a specified radius (in this case 20 km). Focal
variety analyses were conducted separately on the seascapes (which comprise continuous
spatial data) and geomorphology (which comprise categorical spatial data) and the results
combined. Areas where many different seascapes occur are considered as potential habitat
diversity hotspots.
The mandate for creating the seascapes comes directly from the United Nations
Convention on Biological Diversity (CBD), which Australia ratified in 1994. The CBD
requires Australia to set up a system of marine protected areas for the conservation and
sustainable use of threatened species, habitats and living marine resources and ecological
processes. We believe that the seascapes provide a useful method for assisting in the
development of this system of MPA’s by spatially representing seabed heterogeneity in a
consistent, objective and robust way.
The future of seascapes and surrogacy research is to work collaboratively with marine
biologists and ecologists in the formation of seascapes for marine biodiversity prediction,
including undertaking targeted marine surveys to collect further physical and biological data
and building combined databases that permit direct correlation of data. This research will
improve the accuracy and precision with which we can predict Australia’s marine
biodiversity and thus strengthen confidence in decisions about the conservation and
sustainable use of Australia’s marine resources.

Item Type: Report (Technical Report)
Publisher: GeoScience Australia
Additional Information:

© Commonwealth of Australia 2007

Date Deposited: 07 Apr 2008 15:39
Last Modified: 21 May 2013 00:25
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