Coral reefs deteriorate worldwide, but we fail to reliably evaluate their state now and to effectively guide their management because we lack appropriate references of their natural condition. We sampled coral communities from modern (likely a few years-decades old) and fossil reef sites (approximately 7,000 years old) in Almirante Bay (Caribbean Panama) and compared their ecological structure. Modern communities were dominated by Porites and Agaricia, but fossil communities were dominated by Acropora cervicornis (staghorn coral). Our evidence suggests that, at four out of the five modern reefs we studied, community structure has changed significantly since approximately 7,000 years ago; but at one reef, Punta Caracol, it remained within the range of natural conditions. This exceptional reef could either avoid human impact or recover from it–to distinguish between the two, we need to research more. This evidence is spatially limited, but until researchers develop natural references from other regions, it will remain the most reliable evidence to guide reefs' management. In contrast, the conceptual framework we used here scales up to any ecosystem worldwide from which a natural reference can be reconstructed.

Long-term monitoring

Space-time substitution

Models

Historic records

Proxies

–

Symstad & Jonas (2014)

Radiocarbon dates from in situ corals from fossil reef sites in Sweet Bocas.

Also, 9 U/Th dates from Lennond (~2km SE) ranged ~5710-7190 yrs old (Fredston et al. 2013).

Acropora prolifera (left) and Acropora palmata (right) from Sweet Bocas reef (~7,000 yrs old).

Agaricia and Porites were more abundance than Acropora cervicornis since ~1900.

STRI point: White and black horizontal line show boundary pre-post 1900 and 1960 (Cramer et al. 2013).

Agaricia and Porites dominated these reefs over the past ~2 millennia.

C ~ Casa Blanca; F ~ Airport Point 1 (Aronson et al. 2004).

Relative to fossil reef sites in Sweet Bocas (natural reference)

• Punta Caracol approximates natural conditions

• Other subrecent reefs seem in alternative state, but we need to confirm.

Trenching video

Given socio-economical and environmental conditions

(Cinner et al., 2016, Nature)

(Pauly, 1995)

• Outbreaks of Acropora and Diadema diseases,

• too many tourists, and

• overfishing.

Jackson et al. (2014). (Summary slides.)

Jackson et al. (2014). Status and trends of Caribbean coral reefs.