Penguin ‘poop study’ to help unlock colony’s diet

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Researchers from The University of Western Australia and Murdoch University are analysing DNA from the excrement of little penguins in Cockburn Sound to find out what, other than fish, they are eating and whether it is affecting their breeding.

Penguin researcher Dr Belinda Cannell, from UWA, said analysing the animals’ diet in greater detail would provide an insight into their breeding and how it related to the availability of their primary diet, which is fish.

Little penguins in Cockburn Sound (their northern most range in Western Australia) primarily eat anchovies, pilchards, scaly mackerel and sandy sprat.

Penguins are known to also feed on crustaceans, cephalopods and even jellyfish.

“If it’s a poor year and there are not a lot of fish around, the little penguins may be feeding more on other things such as jellyfish,” Dr Cannell said.

This could then have an impact on their ability to produce and raise young.

“This other food may not get them into the condition where they can breed and feed their young,” Dr Cannell said.

“It may be that the chicks don’t fatten up as quickly.”

She said diet made up one element of the project, which is part of the WAMSI Westport Marine Science Program.

Another methodology being used to determine diet composition is the analysis of stable isotopes of carbon, nitrogen and sulphur from the down of little penguin chicks and feathers from adults.

“Stable isotopes of carbon reflect primary production sources and is more enriched in inshore, seagrass dominated areas, compared to offshore food webs,” Dr Cannell said.

“The stable isotope of nitrogen increases up the food chain and can also increase between size classes of the same prey species.”

“Stable isotopes of sulphur can be useful to distinguish between offshore and inshore components in food webs and can also indicate if producers are using sulphur from seawater, which is more enriched, or from sediments which are less enriched.

“This gives us a better idea of the whole diet of these birds.”

Dr Cannell said stable isotopes assist with establishing diet composition.

“I presume little penguins are eating jellyfish, but we haven’t had stable isotopes for jellyfish until now.”

The Western Australian Museum provided samples to assist with the research.

Cockburn Sound research reports now online

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Cockburn Sound research teams have started delivering project reports for their work on the WAMSI Westport Marine Science Program.

These are now published on WAMSI’s Cockburn Sound webpage under ‘Research Themes and Reports‘.

More than 100 scientists and researchers are working across 33 projects, helping to build a picture of the Sound’s environment and provide key input into the port design.

In one of the latest reports to be released, scientists have carried out a detailed literature review identifying potential invasive marine species which may have become established in Cockburn Sound, with procedures to mitigate the risk of introducing these to future Westport facilities.

Another project explores the potential effects of suspended sediment on fishes from dredging, while a social science study has identified and mapped 31 non-fishing recreational activities and 11 associated values for the Sound.

Reports will continue to be published on our website over the next few months.

 

Eco-design and pre-seeding among options to encourage healthy port marine life

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Pre-seeding new port structures to encourage the colonisation of native species is one of the mitigation measures against invasive marine plants and animals, outlined in a new report prepared for the WAMSI Westport Marine Science Program.

The literature review by Curtin University School of Molecular and Life Sciences Adjunct Professor Fred Wells lists many of the invasive marine species that have been recorded in waters around Perth and mitigation measures that could be used during any port construction.

Pre-seeding works by attaching local, fast-growing species to a new structure. The common mussel is one option identified in the report.

Professor Wells said invasive marine species were a worldwide problem and shipping was the most common way they spread to coastal areas. Ninety-eight percent of trade in and out of Australia is on vessels.

“Invasive marine species are concentrated on artificial surfaces and eco-engineering is a new field that attempts to encourage biodiversity and prevent potential marine pests taking hold,” Professor Wells said.

“The risk of introducing new species is greatest during construction but experience during the construction boom in the Pilbara demonstrated the issue is manageable.”

Professor Wells said eco-design was a new and evolving field that could help improve the biodiversity of the marine community that develops underwater, while minimising the risk of invasive species.

“Current design procedures tend to create uniform habitats, such as seawalls with smooth vertical faces. The lack of habitat diversity reduces the biodiversity of the marine community that develops on the structure. “

“Increasing the habitat diversity of new immersed structures and pre-seeding them with native species appear to be the most promising ways for mitigating against species that can cause ecological harm and prove expensive.”

Professor Wells said the biggest threats from invasive species to marine ecosystems were introducing disease, displacing native species, changing the ecology of native communities, clogging pipes and damaging other critical infrastructure.

The report, which was done to understand potential risks, is a literature review of invasive marine species from Cottesloe to Cockburn Sound, including waters around Fremantle and the Swan River.

A comprehensive survey more than a decade ago recorded 60 introduced marine species living in WA waters. Three were on the national marine pest list. Four additional marine pests were subsequently recorded in WA.

“Fortunately, most introduced marine species are apparently innocuous, causing no known adverse effects and we know only a small portion become pests,” Professor Wells said.

 

 

Hippo sedation adapted for Perth sea lion tagging

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Even for a veterinarian who regularly anaesthetises antelopes, giraffes and hippopotamuses, the Australian sea lions off Perth were a new challenge for Werribee Open Range Zoo’s Dr Brett Gardner.

The Victorian based wildlife vet, supporting Dr Simone Vitali – a former specialist veterinarian with  the Department of Biodiversity Conservation and Attractions in Perth – helped fit satellite tracking devices to the endangered mammals after using a novel anaesthetic regime designed to reduce the risk of drowning and aid a quicker recovery.

Dr Gardner said the team working on the WAMSI Westport Marine Science Program satellite tagging operation included boat and beach crews as well as swimmers.

“For sea lions, the water is their safe space when they are stressed but when they have just been anaesthetised it is dangerous for them to be there,” Dr Gardner said.

Traditional methods induce a heavy sedation or even full anaesthesia, which can be risky for the animals.  The sea lions’ anatomy including their breath-holding ability, more compressible ribcage and vulnerable trachea add to challenges around anaesthesia.

“We used a combination of drugs that induce a light sedation, and we had members of the team on the beach and on boats ready to administer medication that reverses their effects in the case of an emergency such as a potential drowning.”

“This lighter sedation is predominantly used to free marine mammals that become caught in fishing line and discarded rope where a heavy sedation would be too dangerous.”

Dr Gardner said the way the sea lions are selected for darting is important.

“We try to target animals that are less likely to react by fleeing into the water, so sleeping sea lions are preferable to ones that are awake.”

The research team works on a sedated sea lion (Photo: Kelly Waples DBCA)

“When we dart animals that are sleeping rather than ones that are alert, they tend to respond like it’s one of their mates that’s bitten them and then they settle down and the anaesthetic takes effect.”

The islands in the Perth metropolitan region are used exclusively by male sea lions but this too posed unique challenges.

“The problem with the Australian sea lion bulls is that they were all on the water’s edge, literally, less than 25 metres away and some are less than five metres from the water.”

“Also, because of their sheer size and their fat deposits you’ve got far fewer suitable areas for a dart to be placed.”

A paper on the anaesthetic regime’s use in Australian sea lions is being written and Drs Gardner and Vitali, said there were no adverse effects observed and the satellite tags were successfully attached to the animals.

 

 

 

 

 

Huge numbers reached in survey of tiny fish larvae 

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The most comprehensive survey of fish larvae in Cockburn Sound has now uncovered more than 40,000 of the tiny creatures from at least 50 families.

Researchers started monthly surveys in September 2021 as part of the WAMSI Westport Marine Science Program.

Researcher Jake Nilsen, from Curtin University, said at least 128 unique taxa had been identified, including pink snapper, whiting, trevallies and flatheads. Sea garfish and yellowfin whiting were recorded for the first time.

Another first-time recording was larvae of the highly sought after King George whiting.

Mr Nilsen said the King George whiting (pictured) was a particularly interesting find given the species typically spawns further offshore.

DNA techniques are also being used for species that are more challenging to identify and where there is limited information on their larval stages, including species of whiting and baitfish.

Now fieldwork has been completed, researchers will focus on analysing the vast dataset to identify patterns of when and where fish use Cockburn Sound during their larval stages.

Researchers from the Department of Primary Industries and Regional Development are also working on the fish larvae project by providing research vessels and staff for the sampling.

Snapper research helping to evaluate hatchery release programs

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Researchers are working on non-lethal ways of evaluating the success of programs that release hatchery-reared snapper fingerlings into Cockburn Sound.

The WAMSI Westport Marine Science Program project, led by the Department of Primary Industries and Regional Development, involves analysing photographs of hatchery snapper to ultimately determine any physical differences with wild snapper.

DPIRD’s Dr David Fairclough, who is working on the WAMSI Westport Marine Science Program project, said the release of hatchery – reared juvenile snapper was perceived as a positive way of improving wild stocks but it was not always clear whether the fish thrived or how long they survived.

“Such information is crucial to assess how hatchery-reared fish may contribute to stocks,” Dr Fairclough said.

The project also involves research scientists from Murdoch University and Flinders University.

“For the research, photographs of the hatchery-reared snapper are imported into a computer program that allows 16 physical features on the fish to be assigned and the distances between them measured,” Murdoch University’s Dr James Tweedley said.

The same process will be conducted on juvenile snapper collected from Cockburn Sound but these fish will also be dissected and have their otoliths – a bone in their ear – removed to determine whether they were grown in the hatchery.  A non-toxic substance is used to stain the otoliths of live hatchery snapper before their release, allowing them to be identified later in biological samples.

“If significant differences end up being detected then, in future, citizen scientists or recreational fishers could become involved in monitoring released snapper by providing photos of their catches for analysis,” Dr Tweedley said.

The project is also investigating whether snapper from inside Cockburn Sound are genetically different than snapper in the open ocean outside the Sound. In addition, it will test if hatchery-reared juveniles contain the same levels of genetic diversity and are as well adapted as those found in the wild population in Cockburn Sound.

“The role of Cockburn Sound as a spawning and nursery area for snapper is well recognised. However, the level of contribution made by those fish to the population and associated fishery along the lower west coast is not fully understood,” Dr Fairclough said.

“Information from this project will help with future identification of where hatchery-reared fish move to, either in Cockburn Sound or along the west coast,” Dr Fairclough said.

Fish frames donated by fishers to DPIRD as part of their ‘Send Us Your Skeletons’ citizen science project, would give researchers an understanding of where hatchery-reared fish move by removing their otoliths to see if they are stained.

 

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.

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.”

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.”

Thousands of creatures uncovered in sediment samples

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Sediment sampling by scientists in Cockburn Sound and Owen Anchorage has uncovered thousands of tiny marine animals and more than 200 unique species.

Researchers from Edith Cowan University, Murdoch University and Western Australian Museum found the animals, known as benthic invertebrates, living in and on top of sediment in 30 sites.

Professor Glenn Hyndes, from ECU, said the sediments were collected across two seasons using a Van Veen Grab Sampler which was operated on a boat to scoop up sediment.

“Sorting and species identification is continuing but at the moment more than 17,000 individuals from eight major invertebrate groups have been found.”

“Sediments from the sites were sieved to remove fine mud which left behind coarse sediment along with the animals,” Professor Hyndes said.

“During hundreds of hours work we found animals such as adult worms, snails, crustaceans, urchins and bivalves which ranged from one to five millimetres in size,” he said.

“We used tablespoons to locate and separate often fragile animals from the sediment.

“Taxonomists at WA Museum have been working constantly to identify the species, characterising the hidden diversity of this urban seafloor habitat.”

He said invertebrates were important because they played a significant role in healthy ecosystems as food for commercially important species, burrowers of sediment and by using multiple life strategies such as parasitism on bigger animals.

“This is the first benthic survey targeting invertebrates to be carried out at this scale in the Cockburn Sound area and the sheer quantity and diversity of invertebrates has been an interesting and exciting discovery.

“The data produced from this work will tie into similar projects focused on the abundance, diversity, distribution and diets of larger animals in Cockburn Sound and the ecosystem of which they are an important part.”

Professor Hyndes is working on the project, conducted under the WAMSI Westport Marine Science Program, with Dr James Tweedley and Dr Sorcha Cronin-O’Reilly from MU, Henry Carrick and Leah Beltran from ECU, along with, Dr Peter Middelfart from WAM, Dr Lisa Kirkendale, Dr Andrew Hosie, Associate Professor Zoe Richards, Oliver Gomez and Ana Hara.

As part of the project, researchers are also investigating the settlement of species on different hard substrates and under different conditions and locations. This project forms part of the WAMSI Westport Marine Science Program and understanding how to improve the effectiveness of substrate in a concentrated area will help develop successful, large-scale initiatives.