Highly conserved thermal performance strategies may limit adaptive potential in corals

Area of Science:

• Marine Biology
• Climate Change Science
• Coral Reef Ecology

Background:

• Rising seawater temperatures pose significant threats to reef-building corals.
• Understanding coral demographic responses to warming is crucial for predicting community shifts under climate change.

Purpose of the Study:

• To measure coral growth rates across a temperature gradient (19°C to 31°C) to define thermal-performance curves (TPCs).
• To assess interspecific and intraspecific variation in thermal sensitivity.
• To evaluate the relationship between thermal optima and growth rates in common coral species.

Main Methods:

• Experimental exposure of coral fragments from four common species to a range of temperatures for one month.
• Calibration of thermal-performance curves (TPCs) for each species.
• Analysis of growth rates and thermal sensitivity.

Main Results:

• Thermal-performance curves showed consistent shapes within species but significant differences among species.
• Low intraspecific variation in thermal sensitivity suggests limited capacity for rapid adaptation.
• A negative correlation between maximum growth and thermal optima was observed, challenging the 'warmer-is-better' hypothesis.
• A trade-off between current and future growth performance was evident, with most species vulnerable to future warming.

Conclusions:

• Warming oceans are likely to reduce coral growth rates, impairing reef recovery.
• Interspecific differences in thermal tolerance and a lack of rapid adaptive potential within species may lead to altered coral community composition.
• Future climate change poses a substantial risk to coral reef ecosystems globally.