‘Shrinking Nemo’: Study finds clownfish can shrink to survive higher sea temperatures

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🗞️ Driving the news: Clownfish have been found to physically shrink in response to marine heatwaves, a novel survival strategy revealed in a new study published in Science Advances
• Researchers tracked 134 clownfish during a 2023 heatwave in Papua New Guinea and discovered that 100 of them shrank in size, boosting their chances of survival by up to 78%

🔭 The context: This is the first known instance of a coral reef fish shrinking in response to environmental stress, highlighting what scientists term “growth plasticity”
• Similar behaviors have only been seen in a few other species, such as marine iguanas
• The discovery comes as marine heatwaves become more frequent and severe due to climate change, posing existential risks to coral reef ecosystems

🌍 Why it matters for the planet: While shrinking helps clownfish survive thermal stress, it reduces reproductive output, potentially affecting population dynamics over time
• These findings deepen our understanding of how marine species adapt to climate stress and may offer insight into broader trends of size reduction in fish, often linked to ocean warming
• It also underscores the fragility of species with limited mobility and dependence on specific habitats

⏭️ What's next: The Newcastle University team plans to investigate the physiological mechanisms enabling clownfish to alter their size and explore whether similar adaptive responses occur in other fish species
• These insights could contribute to better forecasting of species resilience and guide conservation strategies in increasingly unstable marine environments

💬 One quote: “That could be a very positive thing, that they have that capacity and can adapt to their circumstances in that way,” — Theresa Rueger, senior author and marine ecologist at Newcastle University.

📈 One stat: 78% – the increased survival rate for clownfish that shrank during the 2023 marine heatwave.

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