Abstract:

This poster was presented at GeoHab 2010 conference in Wellington NZ, 4 - 7 May 2010.

A program to map the deepwater biotopes of the Australian EEZ is underway based on fine scale acoustic multi-beam echo sounder (MBES) mapping and a newly developed benthic, optical, acoustic grab sampler (BOAGS). Data are collected on specific research voyages as well as utilising transit voyages between ports. These MBES data and associated physical and optical sensing are an important input into assessing key ecological features (e.g. canyons, terraces, banks, seamounts and deep reefs) for regional marine planning, informing the placement of marine protected areas and fisheries spatial management. The acoustic data provide detailed (20 to 50 m grid) bathymetric and inferred substrate information that can be used with other co-variates to predict macro faunal functional groups based on physical and optical “ground truthing”. A consistent approach of interpreting ecological hard and soft substrate based on the acoustic backscatter that maximises the spatial resolution whilst minimises sources of error was developed and applied. This consistent nationally applied acoustic backscatter processing method is highly correlated with visual and physical sampling of the seabed as well as mega fauna diversity. Mega fauna diversity of 6 taxon grouping ~2000 species is highly correlated to both the seabed hardness and the depth of sampling. Nested within a hierarchical classification scheme estimates of seabed hardness are derived for catchments, specific geological features (canyons, seamounts) and MPA’s. Based on this work we propose that seabed hardness as derived from multi-beam acoustics should be included in regional marine planning processes at a number of scales from regional mapping at the 100’s km scale to the 10’s m to 1 km scale for final MPA placement and fisheries spatial management.

Australia’s continental margin defined here from ~150 m to 1500 m, is a narrow strip characterised by high productivity and diversity (Fig. 1). While supporting a major ecological and economic (fishing, oil and gas) resource, this area is poorly-understood yet heavily exploited in parts. A simple first step to assist management of this region is to map the spatial scales of the types of terrain and key components of the biotic assemblages to define marine habitat patches and key ecological features (e.g. canyons, seamounts and deep reefs). Mapping with multi-beam acoustic and optical methods is attractive due to their collective properties: large sampling coverage per unit cost, nondestructive sampling and high spatial resolution.

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