Florida Keys heat wave reveals nearly fourfold death risk for diseased coral

The University of Georgia study published in Coral Reefs reveals that a recent Florida Keys heat wave nearly quadrupled the death risk for diseased coral. Prior research shows that heat stress can cause disease and kill coral, but this new paper demonstrates that corals already susceptible to disease are particularly vulnerable.

Coral health depends heavily on water quality, with poor-quality water frequently hosting more severe disease among corals. Local water quality improvements could boost coral survival, as researchers found. The study also highlights that conservationists should prioritize restoration efforts on the edges of reefs, as these areas are more likely to survive warmer temperatures.

During the extreme 2023 heat wave in the Florida Keys, every square foot of coral colonies experienced record-breaking high temperatures averaging above 87 degrees Fahrenheit for 41 consecutive days. This prolonged heat stress caused severe coral bleaching, which leaves the coral skeleton exposed and makes corals more susceptible to disease and starvation.

Elkhorn coral, once the most common coral in the Caribbean, suffered catastrophic losses during the 2023 heat wave, similar to the death of oak trees across the eastern United States. Edge-located corals benefitted from faster-moving water, which helps remove metabolic wastes and enhances feeding opportunities, resulting in higher survival rates compared to corals further inland.

Reducing coastal pollution, protecting water quality, and focusing restoration efforts on reef edges can improve coral resilience and survival in the face of increasing heat waves.