Researchers in Sydney are on a mission to save the endangered White's Seahorse, combining science and community efforts to protect the iconic species.
On a sunny winter morning, Mitchell Brennan stands at the edge of Chowder Bay, his wetsuit slick with seawater. Behind him, in the nearby Sydney Institute of Marine Science (SIMS) facility, tanks teem with tiny, curled figures - the future of an endangered species. “It's a big day for those little guys,” Brennan says, his eyes bright with anticipation. “They're about to meet their new home.”
As the Sydney Seahorse Project manager and a UTS PhD candidate, Brennan is at the forefront of an ambitious conservation effort to save the White's Seahorse, also known as the Sydney Seahorse. This collaborative initiative, involving UTS, SIMS, and the New South Wales Department of Primary Industries, aims to protect and restore this unique species.
Today, Brennan and his team are releasing 380 juvenile seahorses into the bay, each one a testament to human ingenuity and nature's resilience. What makes this project particularly fascinating is the unusual reproductive biology of seahorses: unlike most animals, it's the male seahorses that carry and give birth to the young. Female seahorses deposit their eggs into the male's brood pouch, where they are fertilized and incubated until birth. This natural oddity has made seahorses a subject of both scientific interest and conservation concern.
From endangered to ‘super’
The White's Seahorse, native to Australia's eastern coast, has faced a steep decline in recent years. Habitat loss and pollution have ravaged their populations, leading to their classification as an endangered species in 2020.
But in the SIMS labs, a revolution has been brewing. Scientists weren't just breeding seahorses; they were creating ‘super seahorses’.
The project began with researchers collecting three pregnant male seahorses from Chowder Bay. In a controlled environment at SIMS, these males gave birth to fry, allowing scientists to refine husbandry techniques crucial for optimising survival rates.
“Mitchell and his team have really worked on determining the optimal temperature, growth, and food required,” explains UTS Professor of Marine Ecology David Booth. “The result? Seahorses that have grown bigger and stronger than any released before.”
The breakthrough came through meticulous experimentation as Brennan and his team refined their husbandry techniques, pushing the boundaries of what was possible in seahorse breeding.
This meticulous approach is essential for increasing the chances of survival as these juvenile seahorses transition into the wild.
A home away from home
As Brennan enters the water, he's not just releasing seahorses; he's introducing them to a carefully crafted habitat. ‘Seahorse hotels’, as they're affectionately called, dot the seafloor of Chowder Bay.
These artificial structures are more than just a clever name. They're a lifeline for a species that has lost much of its natural habitat. “The hotels counteract the loss of seagrass meadows and soft corals,” Professor Booth says. “They're crucial shelters for the seahorses.”
But the innovation doesn't stop there. Each tiny seahorse bears a mark - a visual implant elastomer tag. While visible to the naked eye, these tags also fluoresce under UV light, enhancing their visibility for researchers. This high-tech solution allows researchers to track the survival, growth and reproductive success of each individual.
0%
The estimated natural survival rate of White's Seahorse in the wild.
Citizen scientists to the rescue
As the last seahorse swims off into its new home, Brennan's work is far from over. But he's not alone in his mission. The project has enlisted a crew of underwater observers: local divers.
“We can't be in the water every day,” Brennan explains. “But in Chowder Bay, there are divers in the water daily, so we've launched a citizen science portal where they can submit seahorse photos.”
The project encourages local divers to capture photographs of any seahorses they encounter in Chowder Bay and submit them via iNaturalist, an online platform. This collaborative approach turns every dive into a potential data point, creating a comprehensive picture of the seahorses' progress.
One key outcome of the citizen science component was the first recorded instance of a seahorse moving from the release point on the Chowder Bay swimming nets to the hotels – an observation submitted by a citizen scientist. This valuable data helps researchers understand how the seahorses are adapting to their new environment.
Local divers are also contributing meaningfully in other ways. Many are actively engaged in keeping the bay clean, conducting underwater beach cleans and removing fishing debris from the seahorse hotels. Their efforts highlight the importance of community engagement in conservation work.
A ripple effect
The impact of this project extends beyond the seahorses themselves. A related SIMS project also involving UTS researchers aims to restore Posidonia australis, an endangered seagrass species vital to the seahorses' ecosystem.
As the sun begins to set over Chowder Bay, Brennan acknowledges the challenge ahead. “It's not just about saving one species,” he says. “It's about restoring balance in our marine ecosystems.”
The Sydney Seahorse Project continues to grow. In 2024, over 450 seahorses were released into four locations, and the team has continued to focus on implementing experimental procedures to improve the conservation outcomes. Looking ahead, Brennan and the team aim to breed and release even more seahorses, with the goal of having significant positive impacts on wild populations.
The super seahorses of Sydney may be small, but their impact on marine conservation could be far-reaching. As they curl their tails around their new homes, they offer a powerful reminder: with innovation, dedication, and a little help from nature, even the tiniest creatures can make a big splash in conservation.
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