Deep reefs

The deep reefs of Ningaloo

Up until now research conducted on the deep reef habitats at Ningaloo has been limited. What we do know from the studies that have occurred is that these areas are likely to support abundant, highly diverse, filter-feeding communities – which are identified as important ecological values in the Ningaloo Marine Park’s Management Plan.

Information on abundance and taxonomic composition of these deep reef habitats, along with the ecological processes essential for their long-term sustainability (such as connectivity among areas), are key pieces of information needed to develop effective long-term management strategies for the area. As such, a key objective of the deep reef research theme is to document the extent and character of deep water habitats at Ningaloo.

Ningaloo deepwater habitat observed during a survey – Sponge garden on sand covered low profile limestone reef.

A combination of CSIRO’s in-house Autonomous Underwater Vehicle (AUV) Starbug-X, swath-mapping and towed video techniques are being used to locate and describe deep reef habitats, and to assess the year-to-year variability in the abundance and taxonomic composition of the biota that inhabit them.

Swath-mapping and video drops of deep reef locations at Ningaloo was undertaken in June 2015 at four locations (Tantabiddi, Helby Bank, Mangrove Bay, Osprey), with towed underwater video surveys conducted during August 2016 at targeted areas. Initial analysis of the data is suggesting the main part of Ningaloo Reef (in the areas surveyed) extends to depths of around 35 m, with reef building (hard) corals rare or absent at depths greater than 25 to 30 m. At depths between 35 to 70 m, few reef structures were observed, with the biological communities observed predominantly sponges and octocorals. Extensive beds of shell gravel and crustose coralline algal nodules, and solitary corals were noted at the deeper depths.

CSIRO AUV, Starbug, in action at Ningaloo Reef (Image Credit: Russ Babcock).

As the program moves into its third year of work, the focus will include analysis of video, bathymetry and backscatter data to improve habitat characterisation and initial mapping of deep water reef areas as well as further survey work. The team have now created a habitat map by exploiting the characteristic signals produced by sonar, coupled with data collected from video and AUV field deployments. During 2017 the team even discovered an old anchor, something they didn’t expect to find!

The research team at CSIRO is being led by Senior Research Scientist Dr. Russ Babcock.

Future Scientists

A key element of the Ningaloo Outlook partnership is to provide training opportunities for future scientists. Joe Turner, our PhD Scholar for the deep reef research theme, will be investigating the ecology of deep water filter-feeding communities.