A Heatwave’s Silent Casualties: The Disappearance of Nemo and Its Anemone Home

Sooty Tern

25-10-2025

“But conservation is a concern,” Zhuangzi says. “The people count fish, protect fish, forbid fish from being overfished.”
Kingfisher flutters his wings. “Conservation without Dao is like a river without fish. The fish are not numbers. They are rhythms. I do not disturb the rhythm. I join it.”

In Kingfisherish Wandering [1]

© Bennett-Smith et al. [4]

The 2023 marine heatwave in the Red Sea has left an ecological void once filled with the vibrant partnership of anemonefish and their host sea anemones [2,3]. A recent study by Bennett-Smith et al. [4] published in npj Biodiversity reports the near-complete local extinction of the endemic anemonefish Amphiprion bicinctus and its host Radianthus magnifica following record-breaking ocean temperatures that reached a Degree Heating Weeks (DHW) value of around 22 °C-weeks.

Across three reefs off the central Saudi Arabian coast, the researchers documented a chain reaction of collapse: 100 % bleaching of sea anemones, 94.3-100 % mortality among anemonefish, and up to 94.1 % loss of anemones themselves. Even after partial color recovery, most surviving anemones appeared deflated, shrunken, and unhealthy. Compared with other Indo-Pacific reefs that endured similar heat stress, the Red Sea event produced unparalleled mortality levels. The findings challenge the long-held assumption that this region serves as a “thermal refuge” for coral and cnidarian species, revealing that even heat-adapted ecosystems have limits [5].

The study also reveals how mutualistic relationships—like that between the clownfish and its anemone—can unravel under extreme environmental stress. When the anemone bleaches and loses its symbiotic algae, it can no longer provide nutrients or shelter effectively; the fish, deprived of protection, either perish or abandon their host. Without the fish, anemones lose oxygenation and nutrient input, accelerating their own decline. This breakdown of reciprocity illustrates how climate change can dismantle not just species, but the intricate web of cooperation that sustains ecosystems.

The fading of such iconic species symbolizes more than biological loss; it signals a weakening of ecological resilience. Recognizing that even the most resilient systems can reach a tipping point reminds us of the importance of living in harmony with environmental limits. Cultivating NQ encourages mindful coexistence with other forms of life and collective responsibility for planetary stewardship [6,7]. The disappearance of Nemo’s real-world counterpart is not only a warning—it is a call to rebuild our emotional and ethical connection with the living world [8].

References

[1] Nguyen MH. (2025). Kingfisherish Wandering. https://www.amazon.com/dp/B0FVLLLXNW/

[2] Tietbohl MD, et al. (2025). Extreme marine heatwave linked to mass fish kill in the Red Sea. Science of The Total Environment, 975, 179073. https://doi.org/10.1016/j.scitotenv.2025.179073

[3] Scott A, Hoey AS. (2017). Severe consequences for anemonefishes and their host sea anemones during the 2016 bleaching event at Lizard Island, Great Barrier Reef. Coral Reefs, 36, 873-873. https://doi.org/10.1007/s00338-017-1577-6

[4] Bennett-Smith MF, et al. (2025). Near complete local extinction of iconic anemonefish and their anemone hosts following a heat stress event. npj Biodiversity, 4, 35. https://doi.org/10.1038/s44185-025-00107-4

[5] Osman EO, et al. (2018). Thermal refugia against coral bleaching throughout the northern Red Sea. Global Change Biology, 24, e474-e484. https://doi.org/10.1111/gcb.13895

[6] Vuong QH, Nguyen MH. (2025). On Nature Quotient. Pacific Conservation Biology, 31, PC25028. https://doi.org/10.1071/PC25028

[7] Nguyen MH, Ho MT, La VP. (2025). On “An” (安): Inner peace through uncertainty, nature quotient, and harmony with Dao. http://books.google.com/books/about?id=NIKMEQAAQBAJ

[8] Tran TT. (2025). Flying beyond didacticism: The creative environmental vision of ‘Wild Wise Weird’. Young Voices of Science. https://youngvoicesofscience.org/?p=1963