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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.

Sediment samples at the core of a model project

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Dozens of core samples, taken from sediment around Cockburn Sound, will play a crucial role in the creation of a model of the area’s ecosystem to help inform environmental assessment of the proposed port.

The work, being done as part of the WAMSI Westport Marine Science Program, involved divers collecting three sediment cores from 12 sites and scientists analysing them at a specially created laboratory nearby.

The project is being run by Professor Bradley Eyre from Southern Cross University and Professor Matthew Hipsey, from The University of Western Australia.

Professor Eyre said the tubes of sediment and water were set up in a laboratory, in the garage of a beachside home, where conditions simulated in situ temperature and changing light conditions between night and day, at the sediment surface.

“Some analysis is best done when we have fresh samples, so we wanted to avoid any delays,” Professor Eyre said.

“Other samples will be sent back to the Southern Cross University campus near Byron Bay, which has the only instrumentation in Australia for some of the analyses.”

The 12 locations in the Sound, represent different types of shallow and deep sediments including muds, seagrass meadows, and sandy areas.

“In the laboratory, we were measuring the flux of oxygen and nutrients in and out of sediment including nutrients such as ammonia and phosphate,” Professor Eyre said

“Some of the tubes contained sediment with seagrass growing in it.

“We are also measuring a critical process in the sediments called denitrification.

“Denitrification is a natural process by which ecosystems such as Cockburn Sound can remove nitrogen.”

“It is a really important cleansing process but if the carbon load gets too high the process can be reduced.”

The researchers said data from the sediment testing would underpin new water quality modelling of the Cockburn Sound ecosystem.

“The data complements other key experimental data being collected as part of the WAMSI Westport Marine Science Program on the chemical and biological conditions, allowing the development of Cockburn Sound Integrated Ecosystem Model platform to help manage the system,” Professor Hipsey said

“What we are measuring will reflect what is happening currently in the Sound and when used alongside the modelling we will be able to predict what will happen under future scenarios.”

High tech equipment collecting data beneath the waves

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Wave, current, sonar and camera equipment has been deployed underwater to allow researchers to track sediment flow in and around Cockburn Sound as part of a project which is expected to improve sand nourishment.

Research Fellow Dr Michael Cuttler, from The University of Western Australia’s Oceans Institute, said the research team had set up the high-tech instrument suites during dive trips to three sites.

“At each site, we have the same instrument packages which are designed to measure sediment transport,” Dr Cuttler said.

“They include acoustic instruments to measure waves and currents, and a three-dimensional scanning sonar and custom camera system to map and track seabed morphology.

“The instruments take measurements throughout the day and have already captured significant storm events this winter.”

The equipment is mounted on frames that are attached to steel poles which are fixed to the sea floor.

Dr Cuttler said the systems work to track how and where the sediment moves.

“A lot of our coastal processes work is focused on understanding the beach dynamics – are they accreting or eroding and under what conditions,” Dr Cuttler said.

Dr Cuttler said one of the key knowledge gaps researchers had been trying to fill was sediment transport from the offshore source to the beach.

“Some of the applications for this work is understanding the potential beneficial reuse of dredge material,” Dr Cuttler said.

“So, if they have excess material and want to use it for beach nourishment, where would be the best place to put it and then how long could we expect for that material to move onshore to act as sediment nourishment for the beach.

“One thought is that if you can understand the sediment transport pathways, you can optimise that nourishment, so it continually feeds the beach using natural processes.”

The Coastal Processes project, led by UWA’s Dr Jeff Hansen, is part of the WAMSI Westport Marine Science Program.

The equipment has been deployed three times since the start of the year during different seasons and a final deployment is planned for early 2024.

 

 

 

 

Coral reefs vital for ocean life

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A quarter of all marine species depends on coral reefs but these vital parts of the oceans’ ecosystem are at risk from acidification, pollution, over-fishing and rising water temperatures.

The University of Western Australia’s PhD candidate Josh Bonesso spoke to high school students recently about the significance of coral reefs, as part of the Western Australian Marine Science Institution’s Thinking Blue outreach program. Josh was a finalist in the Student Scientist of the Year category in this year’s Premier’s Science Awards for his innovative research on coral reef islands. He’s also a keen science communicator.

“Coral reefs are nursery grounds for fish, they’re important too for megafauna and the building of coral reef islands that provide nesting areas for many species of seabirds and turtles,” Josh said.

“So, while coral reefs aren’t a large component of the ocean, about 25 percent of marine species rely on them directly and indirectly.”

Josh explained to the Year 12 students how coral reefs formed over thousands of years but that higher-than-normal temperatures and storm events caused by climate change threatened the survival of many coral varieties, particularly fragile branching corals. Mound corals were generally more resilient, but Josh said it was important for reefs not to become homogenous.

“At 34 degrees a species of branching coral, Acropora aspera, exerts a stress response and experiences bleaching.

“We know less about how these corals cope with stress at temperatures below bleaching, at around 32 degrees, and how this impacts their recovery from injury following storm events.”

“But experiments have been done in tanks at that lower temperature where the tops of coral branches are snipped off, to replicate storm damage, and they haven’t grown back,” Josh said.

Thinking Blue is WAMSI’s education outreach program which is designed to educate students about marine science and inspire them to do further studies in the field.

Josh is a PhD candidate at UWA’s Oceans Institute. He did his undergraduate science degree at La Trobe University and initially studied alpine and conservation ecology. But he told the students after a field trip to the Heron Island Research Station on the Great Barrier Reef, he ‘fell in love with coral reefs’.

You can watch Josh’s lecture 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.