Biodiversity, and the factors controlling it, for selected habitats in the Timor Sea region: Physical Oceanography of Karmt Shoals

Despite the major marine bioregions being broadly identified in north western Australia, there has been limited observation and documentation of the marine biodiversity present. The Oceanic Shoals bioregion, which includes numerous shelf edge reef systems, has been identified as a biodiversity hotspot for at least some major taxa, such as sponges, but past research has largely focused on the emergent reef systems at the western end of the bioregion. However, the most common reef types in the Oceanic Shoals bioregion do not reach the sea surface. These submerged reefs, which are biogenic in nature and rise out of deep water to between 10-50m below the sea surface, are very poorly understood and remain mostly to be explored and characterised. As mini seamounts, these reefs may well be areas of both biodiversity and biomass accumulation. The initial task for biodiversity surveys will be a census of submerged reefs to characterise the biodiversity, including its spatial pattern of habitats within reefs, then develop a regional model for habitat types and the location of any diversity hotspots. Integration with data on chemistry, oceanography and geology will be a feature of the Timor Sea study and will permit targeted multidisciplinary projects seeking to understand the processes that sustain the biota of the region. To this end, the distribution of shelf edge upwelling phenomena and natural hydrocarbon seeps, both potentially significant attributes of the bioregion, will be investigated and integrated with data on biodiversity patterns. This report summarises the deployment of 2 instrumented moorings in 50 and 100m water depth near Karmt Shoals in the Oceanic Shoals Bioregion of the Timor Sea. Moorings were set in January 2004, recovered and redeployed in April 2004, and finally recovered in December 2004.