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Southern Cross aquaculture specialist exploring climate change impact

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14 September 2021
Scientist holds up beaker with green liquid

Southern Cross lecturer and researcher Dr Benjamin Mos specialises in aquaculture and human impacts in oceans and waterways. Working from the National Marine Science Centre in Coffs Harbour, Ben is a descendant of the Turrbal people, the original inhabitants of Meeanjin (Brisbane). He believes this rich heritage has helped with his career as a scientist.

"I was very fortunate that my family encouraged me to explore, observe, and connect with nature. The skills and patience I learnt poking around creeks and forests as a kid help me now to observe what's happening in experiments or when watching the way that animals behave. I'd argue careful observation is one of the most important skills you need as a scientist; to be able to observe closely and then pick out meaningful or interesting patterns," said Dr Mos.

In 2019, Dr Mos received an ARC Discovery Indigenous Grant for his research examining how climate change affects animals living in our oceans, estuaries, and rivers. More specifically, he is researching how the larvae of marine invertebrates (like sea urchins and crown-of-thorns starfish) and also animals that move between the ocean and freshwater during their lifecycle, such as freshwater shrimp, are likely to be affected by climate change as nutrients in their food are altered due to ocean acidification and other climate impacts.

"Many of the animals, like snails and shrimp that live in coastal rivers, have larvae that travel to the ocean to feed on tiny microalgae before returning to freshwater to complete their lifecycle.

"We know that climate change is changing the microalgae that live in the ocean. For example, microalgae that grow calcium carbonate skeletons appear to be outcompeted by smaller types of microalgae without shells that grow faster in warmer, more acidic conditions. What we don't yet know is what this means for the larvae which feed on the microalgae. Will they be getting the right nutrition to be able to complete their lifecycle if their usual food is no longer as plentiful?"

Animals that move between the ocean and freshwater during their lifecycle are often important links between these ecosystems. Dr Mos hypothesises that because climate change is changing the food that larvae eat, this might also affect the way that animals carry nutrients from the ocean to freshwater ecosystems and eventually to terrestrial habitats. "I'm excited to find out if my hypothesis is correct," he said.

One of the important nutrients which animals carry from the ocean to freshwater ecosystems is Omega-3 fatty acids. "We know Omega-3 fatty acids are important for human health, but few people know Omega-3s are made only in the ocean by microalgae, with the exception of a few terrestrial microbes. And just like it is for us, Omega-3 is important for the health of animals, including the birds and fish that eat freshwater snails and shrimp. A part of my research is to find out whether climate change will affect the types of fatty acids that larvae incorporate into their bodies and pass onto other animals when they are eaten."

"I'm interested in studying freshwater environments because they are arguably the most impacted ecosystems on earth," said Dr Mos. "Rivers and creeks run through our farmland, our cities, our places of work, our factories, our dumps. We alter their chemistry and flow and dump in our pollution and rubbish. Rivers and estuaries are experiencing the same kinds of climate change effects that we are seeing in the oceans, but at a faster rate. We see evidence of these big impacts with the declines in numbers of fish and other animals that are important to us. I want to know more about what is happening so I can figure out what we can do about it."

Ben grew up exploring a freshwater creek near his family's home. He was always poking around, seeing what was living there, catching fish, shrimps, and bugs with scoops and nets. In his late teens, the family got involved in silver perch aquaculture, setting up a hatchery. During that time, and into his early university years, Ben had his own 'hobby farm', breeding freshwater aquarium fish, yabbies, and shrimp.

During his Honours year, studying a Bachelor of Science with a major in Marine Science and Management, he fell into researching sea urchins.

"I think I was one of the last cohort of students to come through back when the National Marine Science Centre was co-owned by UNE and Southern Cross University. When Southern Cross University took over, I stayed on to complete my PhD and a post-doc with Southern Cross."

Dr Mos' PhD project was on sea urchin aquaculture, and he has continued working with the animals ever since. Sea urchins' gonads, called roe or 'uni' (pronounced oo-nee), are eaten as a delicacy, often in sushi. There is a large market for urchin roe in Japan, part of a global trade worth roughly $150 million annually. Other markets in Asia and Europe are also expanding. Australians are developing a taste for uni after seeing it on TV cooking shows like MasterChef Australia. 

"Interestingly, you run into some of the same problems growing sea urchins in captivity as we see when we look at the impacts of climate change on marine animals. For example, sea urchins find it difficult to grow their shells (also called tests) when the pH of the water is too low. Sea urchins breathe out carbon dioxide, which forms a weak acid and reduces the pH of the seawater in aquaculture systems. A similar chemical process happens in our oceans, linked to increasing carbon dioxide levels in the atmosphere. Working out how to solve the low pH problem for aquaculture has given our research group new ideas to test for combating climate change in the oceans."

The sea urchin research done with Professor Symon Dworjanyn, also at NMSC, has led to the development of a new aquaculture industry in Australia. "After working on growing sea urchins for so long, it's been really good to see the technology I helped to develop licensed and turning into a real industry," Dr Mos said. "I'm hopeful of seeing the industry take off. I'd be ecstatic if in the next few years, there's a number of sea urchin farms here in Australia exporting high quality sea urchin roe to the world, which was raised using sustainable diets in world-class aquaculture systems – technologies developed at Southern Cross University."

Besides crown-of-thorns starfish and sea urchins, Dr Mos also works with fish such as the Blue Tang, better known as Dory from the movies Finding Nemo and Finding Dory (Disney Pixar).

"We have an ongoing project at the National Marine Science Centre looking at breeding Blue Tangs. These fish are really popular in the aquarium trade, but at the moment, they're captured from the wild. Baby Blue Tangs are very difficult to grow because they are very small when they first hatch. Once we work out how to grow them in large numbers, the same techniques will likely be useful for other types of fish."

“I guess I’m still very much that kid who enjoyed playing in the creek. My job allows me to explore the aquatic world every day. But now, it’s even better because I get to create and share new knowledge and technologies that can help my community.”

Dr Mos teaches in first and second year undergraduate units at Southern Cross University; Science and Global Challenges (ENVR1001), Fish Ecology and Aquaculture (MRNE2008), and Invertebrate Life (MRNE2009).

Find out more about studying Marine Science at Southern Cross University.

 

Media contact: Southern Cross University Media and content team, content@scu.edu.au


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