Sea surface temperatures governed the development and longevity of the Great Barrier Reef

Abstract

The Great Barrier Reef (GBR) is by far the largest reef system in the modern ocean. Recently, it has been severely affected by coral bleaching due to human-induced warming. To date, however, the influence of temperature on the origin and long-term evolution of the GBR remains enigmatic. The only available sea surface temperature (SST) proxy data set extending beyond the origin of the GBR shows little variability. It has therefore been argued that other environmental factors must have been responsible for the development of the GBR. Here, we present a TEX86H-derived temperature proxy record from ODP Site 820. It demonstrates for the first time that the onset of reef growth on the outer shelf was preceded by a sharp rise in temperature from ~ 26°C before Marine Isotope Stage (MIS) 17 to ~ 28°C starting at MIS 17. After that, reconstructed temperatures remained relatively high (26 to 29°C). This period culminated in the development of a barrier reef system at MIS 13, suggesting that relatively stable SSTs were critical to its evolution. The glacial MIS 12 showed a renewed cooling to temperatures of ~ 25°C. From MIS 11 to the present, the glacial to interglacial temperature fluctuations approximate 3 to 4°C, with MIS 11 and 5 as particularly warm interglacials. The relatively warm temperatures after MIS 18 likely promoted extensive reef growth even during the glacials. These glacial reefs likely contributed to the persistence of the GBR over several glacial-interglacial cycles since the Middle Pleistocene. The evolution of the GBR, therefore, appears to be closely linked to seawater temperature. Our data suggest that sustained periods of optimal temperatures are a prerequisite for the development and maintenance of the GBR.