History of Indo-Pacific coral reef systems since the last glaciation: Development patterns and controlling factors

Changes in atmospheric CO2 levels remained within the tolerance thresholds for reef calcification. The three main reef growth episodes coincide roughly with rapid increases in atmospheric pCO2. Dust input and variations in sea surface salinities seem to have had a very limited control on reef growth. The LGM was characterized by salinities comparable with those of the present, but by higher dust fluxes. By contrast, nutrient levels, hydrodynamic energy, and to a lesser, extent coral recruitment in relation to substrate availability and ocean circulation, have played major roles in determining reef accretion patterns at both local and regional scales. Two periods of increased upwelling in the western Indian Ocean, at 15.3 and 11.5-10.8 ka BP, coincided with the demise of RGI and RGII. During deglaciation, high-frequency storm events probably led to a scarcity of typical growth framework reefs and favoured the formation of structures composed of reworked and recemented coral framework. Storm control may have been particularly important in the mid-Holocene when water depths over incipient reefs were greater than 5 m. From the LGM to the early Holocene, coral settlement has probably declined due to a lack of suitable nurseries, until the modern patterns of ocean circulation were established and thus favoured larval dispersal from refuges. It is highly desirable to improve analysis of the core database and to increase the number of core-transects, including forereef sites, to enhance our knowledge of Recent reef development.