Huge state delivers vast array of marine ecosystems

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From mud skippers in Kimberley mangroves to orcas in south coast canyons and bizarre looking sea pigs in the deep ocean, Western Australia with its 12,500 kilometre coastline, boasts a vast array of ecosystems, according to marine scientist Dr Tom Holmes.

“In fact, if you include the islands, WA’s coastline is closer to 20,000km which is equivalent to almost half the circumference of the earth,” Dr Holmes said.

In a recorded talk to students, as part of the Western Australian Marine Science Institution’s Thinking Blue series, he discussed WA’s coral reefs, estuaries, mangroves and deep-sea ecosystems.

“There are more than 3,000 species of fish in Western Australia and there are a large number of animal and plants that are not found anywhere else in the world,” Dr Holmes said.

Thinking Blue is WAMSI’s school outreach program which allows students to hear from the state’s top marine scientists on a range of topics.  It’s run with passionate educator and marine scientist John Ryan, who is a teacher at Sacred Heart College in Sorrento.

Dr Holmes, the Marine Science Program Leader at the Department of Biodiversity, Conservation and Attractions, was the first speaker in the latest series of talks and told the students the state they lived in boasted eight of Australia’s 15 biodiversity hotspots.

He explained that mangroves, which are predominantly in the north of the state, supported a lot of life including molluscs, birds and mud skippers. Roots from the plants emerged from the sediment trapping organic matter and allowing the plant to breathe.

“Around Roebuck Bay near Broome scientists have found mangroves are an important area for juvenile green turtles and the area is like a nursery or creche for the animals.”

“There are 13 species of mangroves in the Kimberley and six or seven in the Pilbara.”

Speaking about estuaries, Dr Holmes said they contained a ‘mix of fresh and saltwater species’. One of these was the sawfish, which was a threatened species.

Dr Holmes shared photographs of life in the depths of the Indian Ocean including the sea pig, which is a pink coloured sea cucumber with modified legs and face tentacles.

“It’s a complete alien world at those depths where animals have adapted to live where the environment is cold, with high pressure, low oxygen and low light,” Dr Holmes said.

His talk also covered Western Australia’s spectacular coral reefs, of which Ningaloo is the most famous. He also explained that the biggest individual plant in the world was in WA, a seagrass in the sheltered embayments of Shark Bay.

“This plant has cloned itself over an enormous scale and is now 180km long.”

Dr Holmes finished his lecture, which will be shared with other schools and on the WAMSI website, by taking questions including one from a student about how they could find work in marine science.

He explained he grew up three hours from Queensland’s spectacular coast and learned to dive by retrieving golf balls. Once he had the chance to dive in the ocean, he was hooked on marine life and went on to study marine science.

He said it was a competitive area and it helped to get higher education qualifications.

“But there are many other jobs in this area that don’t require a doctorate including in policy and out in the field as a ranger.

“Get experience where you can, perhaps work towards a skipper’s ticket. It all helps.”

Check out Dr Tom Holmes’ Thinking Blue talk here:

Study examines 30 years of seagrass restoration to find best methods

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A major review of seagrass programs in Cockburn Sound has helped identify the best methods for restoring large scale seabed meadows and found community involvement was a key to success.

Seagrass meadows were decimated from the 1950s and restoration attempts in the past three decades have included everything from sprig and seed-based methods to mechanical plantings, seagrass in sandbags being placed on the seabed and wire coils being used to fix small plants into the sediment.

The project, which is part of the WAMSI Westport Marine Science Program, looked at more than 110 restoration efforts since the 1990s and re-visited 31 sites to assess their success.

The study was led by Professor Gary Kendrick from The University of Western Australia and Professor Jennifer Verduin from Murdoch University.

Professor Verduin said sprig-based programs, where mature seagrass shoots were collected by divers from natural meadows, were found to have achieved high transplant success rates.

“Survival was as high as 90 percent on larger scale sprig-based restoration trials of up to three hectares,” Professor Verduin said.

“We found over a period of 15 to 20 years, the growth of sprigs resulted in the formation of new meadows.”

The study found both sprig-based restoration and seeding programs, such as Seeds for Snapper, had developed viable methods for revegetating large areas of bare seafloor. But large-scale sprig-based restoration programs, while labour intensive, were particularly efficient in quickly stabilising the sediment and creating almost instant meadows. This accelerated the formation of natural meadows.

“Cockburn Sound and Owen Anchorage suffered a major loss of seagrass from the 1950s to the 1990s and while there have been dozens of programs since to rehabilitate the area, there has been limited follow-up to gauge their success,” Professor Verduin said.

“Restoration programs are important and contribute to the rapid natural recovery of seagrass habitats by ameliorating loss and supporting the recovery of grasses.”

“Some of the projects in the past have been on areas of no more than three hectares and we wanted to see if we could recommend a restoration package that could be scaled up to ten times that area to enhance restoration success.”

One of the main findings of the review was confirmation that engaging with local communities was key to the success of large-scale seagrass restoration programs.

Community-based citizen science and restoration projects working with volunteers were recommended as cost-effective approaches to increase the scale of restoration.

“These transplanting projects have already been successful at Southern Flats, Cockburn Sound, and Oyster Harbour, Albany,” Professor Verduin said.

Seagrasses, sometimes referred to as the ‘oceans’ lungs’ are a vital part of the ecosystem. They reduce coastal erosion by stabilising sediment, provide critical habitat for marine animals and efficiently store carbon.

Dozens of recreational uses identified, valued and mapped in project surveys

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Researchers have used data from hundreds of community surveys to create ‘heat maps’ showing the popular spots for 31 recreational activities in Cockburn Sound.

Bird watching, kayaking, jet-skiing and snorkeling were among the many uses identified by almost 600 people who responded to questions as part of the WAMSI Westport Marine Science Program project, which looked at community values in the Sound.

Beach activities, walking, running and swimming were commonly reported forms of recreation and the survey revealed recreation in Cockburn Sound was most highly valued for its contribution to people’s ability to have fun, improve their physical health, socialise with others, and to relax.

Dr Abbie Rogers, a Premier’s Mid-Career Fellow from The University of Western Australia School of Agriculture and Environment, who is leading a theme of socio-economic research for the program, said Cockburn Sound was one of the most intensively used bays in WA.

“The Sound is highly valued by the community for its ecological and recreational values and it hosts a vital part of the State’s economy,” Dr Rogers said.

Woodman Point Reserve, at the northern end of the study area, was found to be the most frequently visited location and beach.

The results were used to create ‘heat’ or kernel density maps that showed activity density or occurrence using circular patterns. Economic valuations were also calculated for recreational use of various sites.

Murdoch University’s Dr Michael Hughes, the project’s lead investigator, said the area was important for recreation.

“The variety of non-fishing recreational activities and associated values that coexist in the Sound highlights the importance of this area for the public,” Dr Hughes said.

The area studied included the shore and waters between Woodman Point and Cape Peron along with Garden Island and Carnac Island. The entire study area was associated with one or more recreational activity values.  “Understanding how people use marine coastal areas for recreational activities and the values associated with such uses, are important considerations for the development and management of these areas,” Dr Rogers said.

Dr Hughes said the ability of the Sound to host such a diverse range of recreational activities suggested the social and physical carrying capacity was considerable.

“Furthermore, management decisions and planning will require engagement with a wide range of recreational activity representatives,” he said.

Of the recreational activities identified and mapped, 16 were land based and 15 water based. They did not include recreational fishing, which is the focus of another project in the program. Other socio-economic projects are measuring the Perth community’s values for Cockburn Sound’s natural environment and ecology.

Students take a dive into marine science with ‘Thinking Blue’

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Students in their final two years of high school are being given access to some of Western Australia’s top marine scientists in a series of lectures on topics ranging from artificial reefs and ecotourism to coral bleaching and aquaculture.

‘Thinking Blue’, which is the Western Australian Marine Science Institution’s school outreach program, lets students hear from inspiring experts across a range of specialist areas.  WAMSI runs the program with John Ryan, a Marine Science graduate who is now a science teacher at Sacred Heart College in Sorrento.

WAMSI CEO Dr Luke Twomey said Thinking Blue was about inspiring year 11 and 12 students as well as taking the latest scientific research into schools.

“The Thinking Blue lectures allow students to hear from people at our partner universities and organisations who are among the leaders in their field,” Dr Twomey said.

“Some students may be inspired to study marine science but all of them develop a greater understanding of the world’s oceans, the threats they face and the role of science in finding solutions.”

The topics for the next school terms include marine pollutants, ecotourism around marine mammals and whale sharks, marine ecosystems, aquaculture as a solution to declining fish stocks and seagrass meadows and mangroves.

The lectures are presented by video link to students at Sacred Heart College and the recordings are shared with other schools and online to the community through the WAMSI website.

John Ryan said the outreach program helped open students’ minds to the wonders of marine science.

“The impact of Thinking Blue extends far beyond the classroom,” Mr Ryan said.

“By connecting students with scientists, it ignites a spark of inspiration, paving the way for a new generation of marine enthusiasts.”

“It is heartening to see that several Sacred Heart College students, driven by their experiences in this program, have chosen to pursue marine-based tertiary education courses, furthering their understanding and commitment to the conservation of our oceans.”

Links to previous recorded lectures can be found here.

First major study of fish larvae in Cockburn Sound

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While fishers head out into Cockburn Sound in search of prized catches such as pink snapper, a team of scientists has been targeting fish larvae to better understand which species are in the area during their earliest life stage and where they are most abundant.

Since late 2021, they have recorded more than 12,000 larvae during monthly sampling.

The researchers say while Cockburn Sound is known to be an important spawning ground for key fishes such as pink snapper, local studies on the larval stage of their development have been limited until now.

Jake Nilsen, a Research Assistant at Curtin University, is part of the team working on the WAMSI Westport Marine Science Program project which also involves scientists from WA Museum Boola Bardip, CSIRO and the Department of Primary Industries and Regional Development.

“We haven’t known a lot about the larval fish in this system,” Mr Nilsen said. “There have only been a few studies and nothing as comprehensive or long-term as the current project. This is the first of its kind to be looking at Cockburn Sound in such detail.”

He said of the thousands of larvae recorded by the team, the most abundant were baitfish, dragonets and filefish, which have to be individually identified to species (if possible) using a microscope.

This was a difficult and time-consuming task given there are so few larval fish taxonomists in WA.

“Important fishery species have also been common, including whiting, trevallies and flatheads which is exciting as it gives new information about their early life stages we didn’t previously understand,” Mr Nilsen said.

“Pink snapper larvae abundance has been relatively low compared to previous studies but observations indicate their abundance is likely to increase following the spawning in October of this year.”

“We are seeing spikes in the number of pink snapper larvae in the most recent samples over the summer period.”

“We know pink snapper use these areas for nurseries and that’s been backed up by the data we’re collecting for the fish larvae.”

“Cockburn Sound is proving to be really important for fish larvae and they are quite vulnerable to environmental stressors.”

Mr Nilsen said two methods were being used to sample larvae.

“The main one is bongo tows which is a net with a small mesh size towed behind a small boat. It basically goes from the surface almost to the seabed and comes back up.”

“In collaboration with DPIRD, we are also using light traps over the summer period to capture larvae that are attracted to light, and just after the snapper spawning period.”

“A promising finding from the light trapping method is the exceptionally high number of invertebrate larvae captured including the larvae of the blue swimmer crab.”

“Work is underway to determine the abundance of the early stages of this species, which remains largely unstudied.”

“Findings from this work may prove useful in restoring that fishery, which remains closed in Cockburn Sound because of concerns about declining numbers.”

He said there was a lot happening in the Sound that couldn’t be seen without a microscope.

“There is a lot going on in the water column.”

How does the ocean’s only flowering plant cope with being buried?

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In water tanks at Edith Cowan University, pots containing Posidonia sinuosa, the most widespread species of seagrass in Cockburn Sound, have been tested to see how much burial under sediment they can withstand. The research, part of the WAMSI Westport Marine Science Program, is looking at the resilience of the ocean’s only flowering plant, to dredging.

ECU researcher, Chanelle Webster, said seagrass was an important part of the ecosystem – providing not only food and habitat for marine animals but also stabilising the seabed and storing carbon which could help combat climate change.

Seagrasses tend to occur in the shallow waters along coastlines as they require a lot of sunlight, but they are easily affected by disturbances in the light reaching the plants.

“One of the main impacts of dredging is changing the amount of light plants receive when sediment is stirred up during operation,” Ms Webster said.

“Another effect of dredging on seagrass is when sediment gets moved and dumped in an area, the particles can settle on seagrass and bury it. This is where my experiment comes in.”

“There are about 10 different species of seagrass in the Sound but Posidonia sinuosa is the main species, you can find it in all areas of the Sound from Kwinana to Garden Island, and this is why we decided to do the experiment with this species.”

“We have been trying to understand how much burial Posidonia sinuosa can tolerate before you start seeing negative impacts to their growth or survival.”

Some of the potted seagrasses had no sediment added, others had up to 16 centimetres of sediment put on them in controlled conditions over four months.

The research team measured the amount the plants grew and noted cellular changes.

“From preliminary analysis, plants tolerate up to four centimetres of burial by sediment but with eight centimetres and more of burial they are impacted.

“When plants were buried by 8cm or more of sediment the growth was significantly less.”

The research indicated Posidonia sinuosa could tolerate burial of four centimetres of sediment for 16 weeks which was the duration of the experiment.

Ms Webster said while further analysis was still to be done, the preliminary results were promising in terms of being able to minimise impacts to seagrasses in the Sound.

WAMSI offering two free student registrations for lobster biology conference

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The Western Australian Marine Science Institution is offering two WA-based Honours, Masters or PhD students the chance to improve their understanding of rock lobster and crab biology with free registration for the International Conference and Workshop on Lobster Biology and Management (ICWL) in Fremantle this October.

The theme of the 12th ICWL is ‘Ecosystem-based fisheries management (EBFM)’ – an approach that recognises all interactions within an ecosystem rather than considering a single species or issue in isolation.

WAMSI is a Bronze Sponsor of the conference and has secured two student registrations to offer people undertaking study at any of our partner universities (Curtin University, Edith Cowan University, Murdoch University and The University of Western Australia) or working at our partner organisations while doing further studies. They must be WA based but can be enrolled at other universities.

WAMSI Research Director Dr Jenny Shaw said it was an opportunity for students to find out more about marine research and fisheries and explore career opportunities.

“The ICWL began in Perth more than 40 years ago. At the time, 37 biologists from six countries met to discuss and compare their work on a range of lobster topics,” Dr Shaw said.

“Since then, it has grown in popularity and prestige.”

“Given the WA rock lobster fishery is the largest single species fishery in Australia with a value of more than $450m annually and was the first in the world to achieve Marine Stewardship Council accreditation, this is a fabulous opportunity for students to learn more about the industry as well as science around the species.

“It’s also a terrific opportunity to network at a prestigious, international conference.”

Students who are interested in applying for WAMSI’s student registration offer are asked to:

Write a letter (maximum of one page) outlining their area of study, explaining how they would benefit from attending the conference and stating where they are enrolled.

Applications should be addressed to Dr Jenny Shaw and be emailed to info@wamsi.org.au by 5.00pm on Monday 4 September 2023. A decision will be made on Monday 18 September.

Details about the conference can be found here.

Study of 1921 Shark Bay cyclone sheds light on present dangers

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A historical account of fish being stranded up to nine kilometres inland by a cyclone in Shark Bay a century ago has been used with numerical modelling to help assess current risks from extreme weather to areas on the edge of tropical cyclone zones.

The cyclone struck the area, 750km north of Perth, in 1921 killing two people, flooding the shores of the outer gulf and causing extensive harm to the pearling industry, seagrass meadows and freshwater wells which remained saline for decades.

The research paper, The utility of historical records for hazard analysis in an area of marginal cyclone influence published in Communications Earth and Environment, reconstructed the cyclone partly through extensive surveys of State and national archives including accounts by a pearling inspector. It also involved using a groundbreaking approach, Quantified Historical Data Framework, to do a structured analysis of archival information to evaluate the authenticity, consistency and relevance of reports of the extreme weather event.

Dr Jenny Shaw, Research Director for the Western Australian Marine Science Institution, worked on the paper in collaboration with researchers from the Nanyang Technological University in Singapore, The University of Western Australia, University of Sydney, Griffith University, Baird Australia and Minderoo Foundation.

Lead author Associate Professor Adam Switzer from Nanyang Technological University’s Earth Observatory of Singapore said the study engaged a diverse team of historians, geoscientists, marine biologists and engineers, showing the need for multidisciplinary collaboration to tackle complex issues such as the risks of cyclones and storm surges in a warming world.

The study noted tropical cyclones were likely to shift poleward in a warming climate and some researchers had suggested the trend was particularly obvious in the Southern Hemisphere.

“This approach provides researchers worldwide with a valuable framework for leveraging historical documents to derive actionable modeling parameters, benefiting areas that face similar challenges,” Associate Professor Switzer said.

Dr Shaw said the study of the cyclone, which struck what is now a World Heritage site, found it had a major ecological impact in a similar way to TC Yasi in Queensland in 2011.

“A recurrence would likely have considerable long-term knock-on effects to ecosystem functions and services, particularly as the seagrasses of Shark Bay contribute to several World Heritage values,” Dr Shaw said.

One of the accounts of the cyclone, found during a search of archives, was by Pearling Inspector Wally Edwards, who witnessed the cyclone and its aftermath.

He described seeing ship groundings, inundated coastal wells, flooding, an altered coastal landscape and sharks and fish stranded inland.

Longer term impacts included livestock losses, declines in the shells used in the pearling industry and reports that dugongs were seen less frequently in the years after the cyclone.

The researchers said a similar cyclone, assessed to be between a category four and five, would inundate the town of Denham flooding critical infrastructure and damaging important industries.

Dr Joseph Christensen, from UWA’s School of Humanities, said the study uncovered detailed information about the historic event.

“By employing the Quantified Historical Data Framework, we were able to establish a detailed and quantified understanding of the 1921 storm surge, including its timing, nature and ecological consequences,” Dr Christensen said.

The authors said the approach had important implications for land use planning, emergency management and environmental management of Shark Bay and other sites of marginal cyclone influence.

Seagrass put to test to find best species for withstanding climate change impact

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Researchers looking at the possible impact of climate change on seagrass have tested the tolerance of the plants to rising temperatures after collecting samples at locations spanning 600 kilometres.

Nicole Said, a research associate from Edith Cowan University who is part of the WAMSI Westport Marine Science Program project, said six seagrass species were collected within Cockburn Sound and one, Posidonia sinuosa was collected along Western Australia’s coast from Geraldton to Geographe Bay.

The samples, which represent species that are all found in Cockburn Sound, were then put in chambers and subjected to incremental increases in water temperature from 15 to 43 degrees over 12-hours.

Oxygen changes in the water were measured to calculate the plant’s photosynthetic rate or the rate at which light energy was converted into chemical energy during photosynthesis. The experiments allowed researchers to understand at what temperature the plants thrived or were stressed.

“It appears from the species that we looked at in Cockburn Sound, the one most at risk from rising temperatures was Zostera nigricaulis which is commonly known as eel grass,” Ms Said stated.

Halophila ovalis, a species found in temperate to tropical areas and commonly known as paddle weed, spoon grass or dugong grass, was most able to withstand the higher temperatures.

Other species tested were Amphibolis griffithii, Posidonia sinuosa (the most widespread species in Cockburn Sound), Posidonia australis and Amphibolis antarctica, which are larger plants than the other two species assessed.

The research team found a heatwave in Perth that produced temperatures between three and four degrees higher than average summer temperatures would be likely to have a negative impact on the larger species which are generally able to withstand pressures for a greater duration than smaller species, but once damaged take longer to recover.

Heatwaves are predicted to become more frequent and more intense under climate change. An extreme marine heatwave in 2010 and 2011 saw a large area of seagrass in Shark Bay destroyed.

“With increasing ocean temperatures and an increase in marine heatwave events, seagrass species living close to their thermal limits are at risk from rising temperatures. There is limited temperature threshold information for seagrass species, which is critical information and can forewarn both present and future vulnerability to ocean warming.”

“There are other researchers around the world looking at climate resilience, but we have been missing this key baseline data to look at the physiology of seagrasses and how they may respond to these climate scenarios.”

ECU School of Science Associate Professor Kathryn McMahon, who co-leads the research on seagrass resilience said the findings were significant.

“These findings are really exciting as they indicate there are differences among seagrass species and population along our WA coast to ocean warming,” Associate Professor McMahon said.

“We can harness these differences and take actions to try and build resilience into our spectacular seagrass meadows.”

From sonar to drones: Fishing around for best research results

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Researchers are using everything from sonar and baited cameras to traps and drones as part of a project looking at the distribution and abundance of key fishes and invertebrates in Cockburn Sound.

The Department of Primary Industries and Regional Development’s Dr Danielle Johnston, who is research lead on the project, said a wide range of methods were being used to monitor larvae, juveniles and adults of commercially, recreationally and ecologically important species. They were being sampled in various habitats and depths.

“February this year marked the end of 18 months of field work which included 220 days sampling with more than 300,000 individual fish and invertebrates identified, representing 244 taxa from 88 families,” Dr Johnston said.

She said using many methods for monitoring and assessing distribution of various species meant researchers needed to spend a lot of time in the field.

”Spring 2022 was the busiest field season to date, with 56 days of sampling, including intensive spawning biomass and larval surveys for snapper and blue swimmer crab.”

DPIRD Scientist Dr Daniel Yeoh, who is part of the WAMSI Westport Marine Science Program team and coordinating field surveys for the project, said drones were being tested to determine if they could be used for surveying changes in abundance of snapper in spawning aggregations.

“Snapper are a bigger fish and can form very dense schools near the surface, so we’re trialing drone surveys to see if we can survey them from the air.”

Sonar was proving useful for detecting schools of snapper further below the surface and the technology was also being used to study schools of smaller forage or bait fish such as sardines and anchovy.

“The acoustics work is being done in collaboration with a CSIRO team in Hobart who are leaders in these acoustic surveys.”

“There are five main species of bait fishes we are looking at including pilchards or sardines and scaly mackerel.”

He said while recreational fishers were sometimes less interested in bait fishes, they were a crucial part of Cockburn Sound’s ecology.

“Some of these species are caught for human consumption or bait, but they are particularly important as prey for penguins and dolphins and we have been providing other researchers with samples and data to use in their projects,” Dr Yeoh said.

“We are looking at what species of fish are found in Cockburn Sound and how their abundance and distribution changes throughout the year.”

“We’re also checking key water quality parameters such as temperature, salinity, dissolved oxygen and turbidity during most of our sampling.”

He said baited remote underwater video stations, which provided researchers with a close-up look at fish, will be put out at more than 150 locations this winter.

“The BRUVs are designed to spot juvenile snapper which were spawned during the last spring,” Dr Yeoh said.

“They grow throughout the year and by winter we can see them on the cameras.”

The project is a collaboration between the Department of Primary Industries and Regional Development, Murdoch University, Curtin University, Edith Cowan University and CSIRO.