Defining variation in pre-human ecosystems can guide conservation: An example from a Caribbean coral reef

Area of Science:

• Paleontology
• Marine Biology
• Ecology

Background:

• Caribbean coral reefs are degraded, with natural states often estimated.
• Human impacts have shifted reefs from Acropora dominance to stress-tolerant species.
• Understanding pre-human reef structure is crucial for conservation.

Purpose of the Study:

• Define the historical range of variation (HRV) in Caribbean coral communities.
• Provide context for modern reef states using fossil data.
• Identify resilient reefs and understand long-term stability.

Main Methods:

• Analyzed fossilized mid-Holocene reefs (7.2-5.6 ka) in Panama.
• Collected bulk samples from fossil reefs and modern reefs.
• Compared fossil coral community structure to modern reef communities.

Main Results:

• Most modern Caribbean reefs fall outside the historical range of variation (HRV).
• Modern reefs exhibit a transition from Acropora dominance to Porites and Agaricia.
• One modern reef remains within the HRV, showing stability for over 800 years.

Conclusions:

• Fossil data define natural variation, highlighting widespread novel ecosystems.
• A stable modern reef, previously overlooked, demonstrates long-term resistance.
• Using fossil records improves understanding of reef degradation and guides conservation efforts.