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| Acoustic signal receivers were installed in coastal waters around Australia for the massive study. (Supplied: IMOS/Fabrice Jaine) |
New data mapping the movements of Australian marine
life over the past decade will provide insight into how climate change
might affect sea animal behaviour, researchers say.
The study by
researchers at the Integrated Marine Observing System (IMOS) and
Macquarie University has tracked the whereabouts of 117 marine species,
ranging from sharks and saltwater crocodiles to sea turtles and
jellyfish using sound-detecting underwater receivers.The receivers pick up and record signals from acoustic tags that have been placed on fish and marine mammals.
Lead author Xavier Hoenner said the researchers collected and quality controlled 49.6 million acoustic detections from tagged animals.
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IMOS Animal Tracking Facility leader Rob Harcourt said the data would help researchers to predict how animal behaviour might change in the future in response to warming waters.
"For example, in the case of bull sharks – a species we tracked that is known to be potentially dangerous – research has shown that they move within warmer waters, meaning it is important that we understand how they modify their movements in response to changes in ocean conditions and processes," Professor Harcourt said.
"We do have quite strong evidence that there are things like pulses of warm water that are coming down with the East Australian Current which is strengthening and has been strengthening over some time.
"With those water masses we find that fish are essentially staying in the same environment but that environment is actually moving.
"Over the course of the next few years we will be able to build some really complex models to allow us to predict what is going to happen as we understand more about the oceanography."
Professor Harcourt said the tracking system showed some species travelled surprising distances.
"For instance, in Sydney Harbour the New South Wales government has been tagging bull sharks because of anxiety about people being bitten," he said.
"Our colleagues up in Townsville, which is about 2,400 kilometres away, also detected bull sharks and then discovered these were the same sharks that had been tagged in Sydney Harbour.
"We are now looking at their movements all the way up and down the coast over a number of years."
Some animals previously thought to be quite sedentary have also been proven to travel long distances.
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"Sevengill sharks were thought to be quite restricted to really cold waters down here, and yet we know now that they go right up to South Australia, again, a couple of thousand kilometres away.
"That is potentially because of the way movements of water have changed."
Dr Hoenner said the tracking data was validated by a state of the art quality control algorithm developed in Hobart, which he expected to be used by other researchers around the world.
The algorithm identifies background noise signals and anomalous movements to strengthen the quality and re-usability of the data.
"There is a global need [for the quality control algorithm]," Dr Hoenner said.
"Everyone is spending a lot of time looking at the data and this could make the whole process a lot easier for everyone."
Professor Harcourt said the data, published in the nature journal Scientific Data, would help future investigations by other marine research groups.
"The data is available through the online Australian Ocean Data Network Portal, making it a very valuable resource for comparing the behaviour of marine animals today and in the future," he said.
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