Where
Gloria Knolls, Coral Sea Marine Park
Who
Jody Webster (University of Sydney) and Robin Beaman (James Cook University)
When
July 2007
Why
Coldwater corals are corals that can exist in the deep (50–4000 metres), dark and cold (4–12 degrees Celcius) waters on continental shelves and slopes, seamounts and ridge systems. They are known to support highly diverse and specialised ecosystems, with many species found only in a singular location, and because they are often very old they are also useful for studying past climate conditions. However, because of the difficulty in reaching these deep-sea regions, little is known about coldwater coral communities or their distribution around the globe.
How
On a research expedition aboard the RV Southern Surveyor in 2007, acoustic mapping revealed an unusual cluster of eight knolls - now recognised as a landslide debris field known as the Gloria Knolls - in depths of up to 1200 metres in the Coral Sea. Using a rock dredge, a sample of these knolls was collected to look into the age and composition of the rock, as well as any biotic communities that might exist on these unusual features.
What did we learn?
The rock dredge sample revealed a unique coldwater coral community on top of the largest of the knolls, including both live and dead stony (scleractinian) corals, soft (bamboo and sea whip) corals, goose barnacles and gastropod shells lying within a muddy sediment. This sample will contribute to our knowledge of the types of species that exist in these deep-reef ecosystems, and help us understand how they got there (dispersal pathways), and how they manage to survive in these difficult conditions. It will also aid in the identification of similar communities around the Australian continental margin and be useful for the conservation of these unique and important ecosystems.
What next?
This discovery has raised as many questions as it has answered: How old are they? What are the links between these corals and their environment? Do these communities exist on other knolls and patches of landslide debris? Projects using radiocarbon dating, barnacle, shell and sediment analyses, and acoustic mapping are underway to investigate the age, composition and geographic distribution of these communities.
Related data and publications
Beaman, R.J. (2009) AINSE Progress Report for AINGRA09006: Understanding coldwater coral ecosystems on the Great Barrier Reef margin, Cairns, Australia, pp.5.
Beaman, R.J. & Webster J.M. (2008) Gloria Knolls: a new coldwater coral habitat on the Great Barrier Reef margin. In: Neil H., & Tracey, D. (Editors), 4th International Symposium on Deep-Sea Corals, 1-5 December 2008. National Institute of Water and Atmospheric Reserach, Wellington, New Zealand, pp. 248.
Puga-Bernabéu, A., Beaman, R.J., Webster, J.M., Thomas, A.L., Jacobsen, G. (2017) Gloria Knolls Slide: A prominent submarine landslide complex on the Great Barrier Reef margin of north-eastern Australia. Marine Geology 385, 68-83. doi: 10.1016/j.margeo.2016.12.008
For more information please contact marinescience@environment.gov.au.