A team of researchers from the Australian Institute of Marine Science (AIMS) has discovered a population of rare benthic siphonophores, in Western Australian waters.
A field of the fragile cnidarians, a relative of sea anemones and jellyfish, was found during a study of an ancient 17,000-year-old WA coastline, which is now 125m underwater.
“We were undertaking towed video surveys to characterise the seabed biodiversity on the Ancient Coastline Key Ecological Feature in the Kimberley Marine Park, when we noticed lots of what looked like “pom poms” seemingly floating just above the seabed,” Dr Miller said.
“On closer inspection of high-resolution images, we realised what we were seeing were fields of benthic siphonophores.
“As far as we know, there have been no other benthic siphonophores recorded in Western Australian waters, and the only other reported observation in Australia was in the Great Australian Bight.
“These creatures are generally found in deep water down to 3000m, and are rarely ever seen; hence why our observation in depths of 100m to 150m is so exciting.”
Dr Miller said the discovery emphasised how little is known about these marine ecosystems, and the importance of protecting undiscovered biodiversity.
“The ancient coastline is thought to provide crucial habitat for sponges, corals, crinoids, molluscs, echinoderms and other invertebrates, particularly where it emerges as rocky outcrops in a surrounding environment dominated by soft sediments,” Dr Miller said.
“We have been working with an international taxonomist and we think these siphonophores are likely to be a species of Archangelopsis, although they are very hard to identify from pictures and video alone.
“To properly identify this species we will need to collect specimens and work with international taxonomists to determine if it is a new species, or one that is known from other oceans.”
This will be a challenge for researchers, since collecting samples of such fragile animals from depths over 100m will require specialised equipment.
In the meantime, AIMS researchers will be on the look out for more benthic siphonophores on the northwest shelf and in Australian marine parks.
Dr Miller said less than 25 per cent of Australia’s Exclusive Economic Zone (EEZ) has been mapped, and there is a great need for further baseline biodiversity surveys, in order to better understand the values within marine parks and to protect their unique features.
Find out more about these marine animals at the Australian Marine Parks Atlas:
Unique footage of the benthic siphonophores in WA:
Australian Institute of Marine Science
Media Officer Emma Chadwick
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