Big Bank Shoals of the Timor Sea

Big Bank Shoals are submerged carbonate banks that rise from the Timor Sea, where the Australian Continental Shelf deepens steeply towards the Timor Trough. Standing in 20 to 30 metres of water, these submerged banks form ecosystems that support habitats for a range of communities. They were, until recently, uncharted.

The light penetration to and movement of nutrients around the sea mounts mean that the Big Bank Shoals communities differ greatly from those in the surrounding deeper waters (200 to 300 metres).

AIMS research shows that the banks in the Big Bank Shoals fall into three distinct sea floor ecosystem categories:

• The Halimeda (algae) dominated ecosystem, which was the dominant type for the area. Halimeda was noted to be viable in a wide range of habitats, which contributes to the considerable success of the group in the area.
  

• The coral dominated ecosystems, which, as with Halimeda, were restricted to the shallower banks. Coral was most important where hard substrate existed on the plateaus of the banks, most noticeably around the bank rims.
  

• The filter-feeding ecosystem, which dominated the deeper banks due to light restrictions. A mix of sponge types and soft corals such as gorgonians were common features of these banks.

Information gathered from the Big Bank Shoals has been published in an environmental resource atlas. The atlas is a compilation of the various studies and reports from the individual environmental study programs conducted during 1995 and 1996, as well as literature research on the various biological communities encountered. It is a joint effort by BHP Petroleum and AIMS to further analyse the results of field investigations and to attempt to draw some conclusions based on the present state of knowledge of the environment.

November 7, 2007