Robot sowing the seeds for healthy seagrass meadows

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A robot that plants seagrass seeds directly into the seabed is being trialled in Cockburn Sound as part of a program to speed up the restoration of badly depleted underwater meadows.

Seagrass, the ocean’s only flowering plant, is vital as a habitat for wildlife, for stabilising sediment and storing carbon. But pollution, marine heatwaves and development have wiped out vast areas of seagrass meadows.

Emeritus Professor Gary Kendrick, from The University of Western Australia’s School of Biological Sciences, who is a seagrass restoration project leader on the Western Australian Marine Science Institution (WAMSI) Westport Marine Science Program said it wasn’t enough to let ‘nature takes its course’ because the process was too slow.

“In Cockburn Sound, south of Perth, we are talking about a system that lost more than 3,000 hectares of seagrass from the mid-1950s to the 1980s,” Professor Kendrick said.

“Less than 100 hectares has come back.

“Even when we disperse seagrass seeds where the plants are needed, it can take two or three weeks for them to attach to the sediment and in that time, most are lost.”

The specially designed autonomous robot, which is powered by batteries, injects seeds into the seafloor which the research team said improves their chances of taking hold and growing into healthy, new plants.

It was developed by Ulysses Ecosystem Engineering, which is based in San Francisco.

Their team travelled to Perth to operate the machinery trial. The robot works by taking collected seeds and depositing them directly into the seabed. This has been shown to have a greater germination rate than traditional methods of restoration, which see the seeds scattered at the surface.

Professor Kendrick said the trial had come a long way.

“I have worked with the Ulysses engineers for one year and in that time, we have now got a full robotic system working.”

“Next year we are hoping we can demonstrate you can plant a hectare in a day.

“We are seeing a slow recovery at Kwinana Shelf and what we are really trying to do is speed it up and build resilience in a whole community.”

Researchers from UWA will return to the trial sites to assess for restoration success over the next year.

Will O’Brien, one of the co-founders of Ulysses said it is crucial that we develop automated solutions for seagrass restoration.

“Existing methods are too expensive and slow to achieve the results that are needed,” Mr O’Brien said.

“This trial is the first step in restoring WA’s seagrass coverage to historic levels and we are off to a very promising start.”

The trial will be supported by a $230,000 investment by Westport.

Photo credit : Nina Ho, UWA

Squid on camera in sediment project

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Cameras set up in large tanks are capturing what impact varying levels of fine limestone sediment in the water has on the feeding habits of squid, as part of a project for the WAMSI Westport Marine Science Program.

The project, which started recently, is led by Dr Ben Saunders, a Senior Lecturer in the School of Molecular and Life Sciences at Curtin University.

It will be used to inform the Westport project in Cockburn Sound.

Dr Saunders said traditionally research had focused on the lethal effects of sediment on marine life during dredging operations.

“What we are interested in is the lowest measurable effects, where the behaviour of the animal starts to change,” Dr Saunders said.

“They may start to feed differently and there could be changes to their body condition and overall health.”

Three levels of sediment are being used to replicate what is likely to be in the water during a dredging operation.

“We are testing 25 milligrams per litre, then 44 milligrams per litre, and a control without added sediment.”

The highest level is based upon the turbidity levels where previous research suggests that 5% of fish species begin to be affected.

“We feed the 17 squid in front of the video cameras and we try to get them to come in so we can record any delay between the fish going into the tank and the squid realising it is there and coming in to eat it.”

One sign the squid may not be able to see their prey is fish remaining uneaten at the base of the tank.

Two trials will be conducted, and each trial runs for 10 days.

The squid are fed and monitored three times a day and researchers regularly test water quality and monitor the video footage.

Ocean soundscapes as varied as landscapes

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Underwater soundscapes are as varied as landscapes, according to acoustics researcher Dr Iain Parnum.

Dr Parnum gave a presentation for the Western Australian Marine Science Institution’s Thinking Blue school outreach program about marine soundscapes, which are a growing area of research interest.

Dr Parnum is a Senior Research Fellow at the Centre for Marine Science and Technology (CMST) at Curtin University and the Centre’s Deputy Director. He is also a Noise theme researcher on the WAMSI Westport Marine Science Program.

“In marine ecosystems, sound is vital to many species for navigation, communication and finding prey,” Dr Parnum said.

“For about 12 hours a day we have no light, so sound is important for a lot of marine life because sound waves are not inhibited by a lack of light.”

“But different areas of the ocean have vastly different sounds.”

He said there was an increased research focus on underwater soundscapes and the impact of noise on animals.

Dr Parnum said one of the soundscapes he had studied was the Perth Canyon, which is a deep submarine canyon 20 kilometres west of Rottnest Island. It is an important feeding ground for many animals and the area is also traversed by ships and other vessels.

He said between 2008 and 2016 an acoustics laboratory recorded the canyon’s underwater soundscape, including migrating whales, fish choruses and earthquakes, as part of a program designed to improve the understanding of noise and its impact on marine life.

Data from the sound recorders are used to create spectrograms which illustrate the energy, pitch and patterns of sounds.

“These then become an efficient way of monitoring the presence of these whales in the canyon and in other areas because we know their distinctive sounds,” Dr Parnum said.

He said Antarctic minke whales produced a noise, which submariners referred to as  ‘bioduck’ when they first recorded the mystery sound.

“Humpback whales meanwhile are the showoffs of the whale world and produce more complex songs with high and low frequencies.”

“The males will sing songs for hours at a time and elements of the song will be picked up and used by other pods.”

By understanding the various noises made by the whales, researchers have been able to identify when they are using the canyon.

“Pygmy blue whales are present in the canyon from November to June and peak between March and June.”

“The peak times for humpback whales in the Perth Canyon are June and July, during the northern migration and August to October when the species migrates south to Antarctica.

You can find out more about Dr Parnum’s work in Cockburn Sound here.

You can see Dr Parnum’s full Thinking Blue presentation here and find more information about the Perth Canyon acoustic observatory including access to the data here.