Table 1. Diverse reef responses to natural acidification in the Palau Rock Islands, PNG CO2 vents, Mexico ojos, and eastern tropical Pacific (ETP) upwelling regions.
For each site, response variables are reported as the ratio of each variable in low/high pH sites. + indicates a significant increase in the response variable from high to low pH, and − indicates a significant decrease. n.d., no data available.
| Palau* | PNG† | Mexico‡ | ETP§ | |
| Hard coral cover | 1.9 | 1.1 | 0.5 (−) | 0.0 (−) |
| Macroalgae cover | 0.7 | 2.1 (+) | n.d. | n.d. |
| Coralline algae cover | 1.1 | 0.2 (−) | n.d. | n.d. |
| Hard coral richness | 1.6 | 0.6 (−) | 0.3 (−) | 0.2 (−) |
| Porites cover | 16.0 (+) | 2.3 (+) | 0.8 | n.d. |
| Porites extension | 1.0 | 1.1 | 1.0 | 0.6 |
| Porites density | 0.8 | 1.0 | 0.8 (−) | 0.8 (−) |
| Porites calcification | 0.8 | 1.1 | 0.7 (−) | 0.5 (−) |
| Bioerosion¶ | 11.3 (+) | 1.9 (+) | 1.8 (+) | 1.9 (+) |
*For Palau, ratios are calculated for the two lowest and the two highest Ωar reefs, and the indicated significance is for the trend across all sites (Ωar = 3.7 to 2.3).
†For PNG, ratios and trends are reported for Ωar = 3.5 to 2.9 (13).
‡Community data for Mexico are reported for Ωar > 2.5 to Ωar < 2.5 (37), and skeletal growth parameters are reported for Ωar > 2 to Ωar < 2 (14).
§For the ETP, hard coral cover, hard coral richness, and Porites extension, density, and calcification data are reported for four reef sites within the Galapagos (Ωar = 3.3 to 2.4) (39). Porites macrobioerosion rates are compared across the Galapagos, the Gulf of Panama, and Gulf of Chiriquí (Ωar = 3.5 to 2.5) (38).
¶Trends in bioerosion are estimated by the percent volume of macrobioerosion of Porites skeletal cores (Palau and Mexico), Porites bioeroder density (PNG), or bioerosion rate (ETP).