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Coral in water off the coast of Cape Otway.
What we can learn from seabed mapping

When researchers mapping underwater reef habitats stumbled across the ‘drowned apostles’ off Victoria’s south-west coast, it was an exciting find for scientists. But geological discoveries are not the only benefits coming out of deep sea research and mapping.

Dr Daniel Ierodiaconou from Deakin University’s School of Life and Environmental Sciences is one of the people conducting this research. Uncovering secrets of the deep, he’s collecting data that provides crucial information about changes to Victoria’s coastal marine habitat that will help us plan for a more sustainable future.

What does your research involve?

‘Most of our work focuses on mapping plant and animal communities on the sea floor, as well as mobile fish species. First, we collect physical information to characterise the seascape. Then we use this information to prioritise sites to obtain biological collections, often using remote techniques such as baited cameras, remotely operated video and autonomous underwater vehicles, as they are beyond safe diving depths. We then integrate this information to make predictions about species distributions, abundance and connectivity of habitats. High-resolution sonar data has enabled us to develop a detailed continuous map of Victoria’s sea floor habitats.’

Why is this research necessary?

‘There are so many knowledge gaps. Many of the locations we are currently working in have not been visited since Matthew Flinders circumnavigated Australia. Our research is important because coastal marine habitats are under threat from humans’ use and associated impacts. Without this data it is difficult to make informed management decisions. For example oil and gas exploration in south-west Victoria is likely to proliferate, with the region also being identified as an important area for offshore renewable energy, such as wave energy facilities. In some areas, marine communities are changing due to climate change and range expansion of certain species. More than 90 per cent of the animals found in cool temperate waters of Australia are found nowhere else on Earth, so we need to do what we can to protect them. This research also helps us understand the reef estate supporting our fisheries, so we can sustainably manage our marine estate.’

How have underwater mapping techniques evolved?

‘Well, Flinders did it with a lead line. In the 60s we saw the proliferation of single beam echo sounders, as seen on a typical fishing vessel. This involves a transducer (sonar head) sending out an acoustic pulse and the depth is worked out based on the time it takes the sound to return. Take a leap forward to today and we have Deakin’s $650,000 research vessel Yolla, which has the most advanced sonar system in the world. Her latest generation multi-beam sonar system is capable of measuring 400 beams up to 50 times a second – that’s 1.2 million soundings a minute! It allows us to get very detailed information of a seabed and can reveal features such as the drowned apostles or even micro-ripples at centimetre scales.’

'More than 90 per cent of the animals found in cool temperate waters of Australia are found nowhere else on Earth, so we need to do what we can to protect them.'

Dr Daniel Ierodiaconou,
School of Life and Environmental Sciences, Deakin University

What else have you discovered?

‘We are only just starting to understand the biodiversity value of these deep reefs because often we are collecting information on these habitats for the first time. We’ve found amazing deep water habitats that rival the corals of the Great Barrier Reef in terms of their complexity, colour and beauty, as well as diverse invertebrate communities. We have also imaged geological features for the first time such as ancient river systems, lava flows, underwater valleys and mountains, and caught glimpses from a not-too-distant past, including ship wrecks. Most areas we map were once terrestrial and would have been extensively used by the Indigenous owners of our land. We are in discussions with some of these communities to see how our information can help tell their stories.’

How has your data been used?

‘I like to think the data we collect has multiple benefits. For example the data collected around the drowned apostles was originally funded by Natural Heritage Trust to collect seafloor data to assess the representativeness of underwater habitats in marine parks. Since then the data has also been used to investigate fish–habitat relationships for Parks Victoria; in a Fisheries Research and Development Corporation project to investigate habitat connectivity for rock lobster and abalone fisheries; to seed larval dispersal and work out the role of oceanography on fisheries productivity; to plan seismic surveys and clearance of the seabed; to assess a gas pipeline and impacts of sediment scour; and to prioritise locations for wave energy facilities. It’s very multipurpose!’

How will your research impact the future?

‘I say to my students that what we are doing now is important but the real value will be in 10, 20, 50 and 100 years’ time when the data we are collecting is revisited to determine what impacts we are having. I also hope my research will encourage the conservation and fisheries sectors to work more closely together. I feel we are making headway here. A recent collaborative survey of rock lobster populations in marine protected areas assisted Parks Victoria as it was the first survey of its kind since the marine parks network was established, and assisted the fishery by providing important reference information for a non-fished population. Ultimately my research will provide a baseline to support fishery and conservation management of Victoria’s marine environments and will hopefully influence policy and management practices to the benefit of our marine and coastal systems.’

Find out more about the research being conducted in Deakin’s School of Life and Environmental Sciences.

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Dr Daniel Ierodiaconou
Dr Daniel Ierodiaconou

Senior Lecturer in Aquatic Spatial, Deakin University
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