Fig 1.
A) Location map of the Coral Gardens Reef study area; B) Inset map of Coral Gardens located between Ambergris Caye (San Pedro) and Caye Caulker islands. C) Pits A, B, and C were excavated in areas of non-living reef framework. T1-T5 represent transect locations across patches of living Acropora cervicornis. Images used in A and B are modified from Landsat-8 imagery courtesy of the United States Geological Survey.
Fig 2.
Sampling location and character.
A) Non-living substrate at T5 prior to excavation (Photo: Lisa Greer); B) Excavation Pit C with vertical metric scale bar. Each black or white bar on the scale represents 10 cm; maximum depth of this pit was 2 m (Photo: Lisa Greer); C) Typical area for dead coral sampling and canopy structure at T5 (Photo: Lisa Greer); D) Open coral canopy facilitated non-destructive sampling of coral rubble within living coral patches (Photo: Lisa Greer).
Table 1.
Number of samples collected, analyzed using XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), stable isotope, radiocarbon and U-Th analyses, and results of radiocarbon and U-Th dating.
Twenty- six samples were cross-dated with radiocarbon and U-Th methods.
Fig 3.
A) Acropora cervicornis rubble sample with outer surface removed prior to screening (Photo: Tanner Waggoner); B) Scanning electron microscope image of a coral surface with no visible signs of alteration (Photo: Tanner Waggoner); C) Crushed aragonite coral skeleton free from contaminants viewed from under a binocular microscope (Photo: Tanner Waggoner).
Fig 4.
All 230Th and radiocarbon dates from Pits A, B, C and the modern canopy at Coral Gardens, color-coded by sample population and with standard error plotted on the radiocarbon calibration curve from Glovers Reef, Belize [88]. Circles represent radiocarbon dates and diamonds represent 230Th ages. 230Th ages are used in place of all radiocarbon ages for cross-dated samples. Unfilled diamonds represent samples with 230Th ages that were not radiocarbon dated and therefore do not have a F14C value. The ages of these samples are indicated below the radiocarbon calibration curve for Glovers Reef [88] for ease of visualization.
Fig 5.
Continuity of Acropora cervicornis growth at Coral Gardens.
All U-Th and radiocarbon ages of samples from Pit C and from within the modern living canopy. Note the substantial chronological overlap between corals from within living coral canopy and beneath the death assemblage (boxed) during the time of Caribbean-wide demise of acroporids. Abundant living corals were observed at least annually from 2011 to 2019.
Fig 6.
Typical view of flourishing live coral at location T5 in November 2019 (Photo: Lisa Greer).
Fig 7.
Coral Gardens in relation to reef crest.
Red indicates the line of shallow reef crest off Ambergris Caye. Yellow indicates outline of Ambergris Caye (north) and Caye Caulker (south). Landsat-8 imagery is courtesy of the United States Geological Survey.