These iconic corals are nearly extinct due to heatwaves: can they be saved?
Summary
Two of Florida’s primary reef‑building corals, the elkhorn (Acropora palmata) and staghorn (Acropora cervicornis), have been declared “functionally extinct” across much of the state’s southern reef after an unprecedented 2023 marine heatwave. A Science study reports mortality of 98–100% for these species across large stretches of the 560 km reef, although survival rates were higher (around 60%+) further north and near Miami.
The 2023 event produced sustained temperatures above 31 °C for nearly 41 days and heat exposures 2–4 times higher than previous records. Conservation work that focused on rearing and outplanting Acropora for two decades has been largely wiped out, prompting a strategic shift: practitioners are now prioritising more heat‑resilient corals, preserving genetic diversity of surviving Acropora individuals and exploring breeding approaches that could improve thermal tolerance.
Key Points
- The 2023 Florida heatwave caused extreme bleaching and near-total mortality of elkhorn and staghorn corals across much of the reef (98–100% in many areas).
- Ocean temperatures remained above 31 °C for almost 41 days, producing heat exposures far beyond previous records.
- Researchers now consider elkhorn and staghorn “functionally extinct” as reef builders in southern Florida — the ecosystem has been fundamentally transformed.
- Conservation strategies are shifting from large‑scale outplanting of Acropora to protecting resilient species (e.g. brain and star corals) and preserving genetic stock of surviving Acropora.
- Breeding and selecting heat‑tolerant individuals shows promise, but such efforts have not yet been implemented at the scale required to restore former reef function.
- Survival was not uniform: some northern and Miami‑adjacent reefs fared better, offering sources for genetic rescue and research.
- The finding highlights how single extreme events can erase decades of conservation progress and force a rethink of restoration goals.
Context and relevance
This article is important because it documents a clear instance where climate‑driven extremes have removed keystone habitat builders — a warning that many reefs globally could face an accelerating collapse in structure and function. For conservationists, policy makers and coastal managers the piece signals a pivot point: restoration can no longer assume historical baselines will return, and strategies must incorporate heat resilience, genetic preservation and triage of priorities.
It also ties into broader trends: more frequent and intense marine heatwaves under climate change, the limits of current restoration methods, and the need for integrated approaches that combine mitigation, adaptation and targeted assisted evolution research.
Author style
Punchy: this is not just bad news — it’s a wake‑up call. The article makes clear that the reef has changed in ways that demand new, bolder conservation planning. If you care about ecosystems, coastal communities or climate impacts, the detail matters.
Why should I read this?
Short answer: because this shows how a single extreme heatwave can wipe out species that built whole reefs for millennia — and why the usual fix (grow them in labs and plant them back) might no longer be enough. If you want to know what successful coral conservation could look like next, read on.