OUR FUTURE

Kangaroo Island community congregate over a pint to save our sea lions

MARINE SCIENCE: Tanya Rosewarne, Mariel Fulham and Dr Rachael Gray at the science in the pub talk about Kangaroo Island's resident Australian sea lions. Photo supplied

MARINE SCIENCE: Tanya Rosewarne, Mariel Fulham and Dr Rachael Gray at the science in the pub talk about Kangaroo Island's resident Australian sea lions. Photo supplied

Three marine scientists walk into a seaside pub...it sounds like the start of a joke, but their research is no laughing matter as they join forces over a friendly pint with local communities to spread the word about Australia's vanishing sea lions.

Leading researchers Dr Rachael Gray and Mariel Fulham from the University of Sydney, along with National Parks and Wildlife Service's Tanya Rosewarne recently presented their research findings into Kangaroo Island's resident Australian sea lion (Neophoca cinerea) population to locals at the Ozone Hotel in Kingscote on Thursday evening, Nov. 25, 2021.

Tanya Rosewarne, one of the presenters at the Science in the Pub event, said it was a full house with more than 40 locals, who were keen to hear more about the important research and the ongoing work being done to protect the health of the Seal Bay sea lions.

With a Master's degree from Macquarie University into how protected areas are an essential tool for species conservation, Tanya shared her analysis of more than 30 years of data from the Department for Environment and Water about the sea lion's breeding trends in the area.

BREEDING COLONY: Seal Bay Conservation Park on Kangaroo Island is an important breeding location and a tourism site for Australian sea lions. Photo supplied

BREEDING COLONY: Seal Bay Conservation Park on Kangaroo Island is an important breeding location and a tourism site for Australian sea lions. Photo supplied

"Seal Bay Conservation Park on Kangaroo Island is an important breeding location and a tourism site for Australian sea lions, with three refuge areas without human presence and one zone for tourists," she said.

"Analysis of population trends between 1986 and 2019 showed that the population peaks between 18-month breeding cycles were equivalent across all zones, however, distribution across the cycle for each zone varied.

"Trends showed declines in the westerly areas which include prohibited and tourist zones, and non-linear increases in the eastern prohibited area. Temperature, wind speed, tourism numbers and landscape changes were considered potential drivers of these trends.

"These population changes are the starting point of analysing the effectiveness of zones for protection."

Dr Rachael Gray from the University of Sydney said that the recent upgrading of the Australian sea lion from threatened to endangered status highlights the urgent need to investigate, and mitigate, key threats to the species' recovery.

"Upon European colonisation, Australian sea lion populations were decimated and nearly driven to extinction. While their populations have been slowly recovering, these animals are facing a new range of threats, and once again, the impacts of humans are a leading cause," Dr Gray said.

"A key threat to population recovery is the high rate of pup deaths which is caused in part by hookworm disease.

"Hookworm disease is an infection seen in 100 percent of Australian sea lion pups studied in Seal Bay, Dangerous Reef and Olive Island, and one that contributes to significant disease and death.

"Adding to this threat, Australian sea lion populations are affected by high levels of mercury which is known to cause suppression of the immune response, which could increase the susceptibility of pups to hookworm infection.

"Recent work by University of Sydney PhD student, Shannon Taylor has shown that at the time of peak hookworm infection, mercury levels are high."

Dr Gray and a team of researchers have also been investigating the use of a veterinary anti-parasitic medicine.

"During the 2019 and 2020/21 breeding seasons, treatment trials were conducted at Seal Bay using a topical application of an anti-parasitic drug called Ivermectin, which is typically found in cat and dog flea and parasite treatment tablets and has been commonly used to treat parasites in cattle and sheep," she said.

"To test the effectiveness of Ivermectin in mitigating the effects of hookworm disease in pups, the team made comparisons in health, growth, and pup survival in ivermectin-treated and untreated pups.

"Results from University of Sydney PhD student Scott Lindsay's project showed significant improvements in several blood parameters, which indicated improved health in pups that were treated.

"Importantly, treated pups had significantly greater growth in weight and length, benefits which were sustained throughout the study period.

"We also saw improvements in pup survival during the high mortality 2020-2021 summer season, which we hope will contribute to population recovery."

Researcher Mariel Fulham said that in recent years the importance of gut bacteria on human health has become increasingly apparent.

"The gut microbiota affects the health of their host and can influence physiology and behaviour and are essential for proper function and development," she said.

"Our team, in collaboration with Associate Professor Michelle Power at Macquarie University, is investigating the impact that removing hookworm could have on Australian sea lion pups."

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