Disturbances with hiatuses in high-latitude coral reef growth during the Holocene: Correlation with millennial-scale global climate change

Recent studies have reported Holocene millennial-scale climate instability at a global scale. However, the relationship between this climate variability and coral reef growth is still unclear. Field observations and high-precision, in situ coral radiocarbon dating of the excavated trench walls of an uplifted middle-to-late Holocene coral reef on Kodakara Island, located in the pathway of the Kuroshio Current in the northwestern Pacific, show evidence of the existence of disturbances with hiatuses in coral reef growth and coral composition differences before and after the disturbances. We found three disconformities in the reef, and the dating results indicate that disturbances with hiatuses in reef growth occurred at approximately 5.9 to 5.8, 4.4 to 4.0, and 3.3 to 3.2 cal yr B.P. The results also indicate that the second and third events were associated with sea-level oscillation. The timing of the disturbances corresponds well with the periods when the Kuroshio Current was relatively weak and was associated with a relatively cold sea surface temperature, which may have enhanced the cold winter Asian monsoons, and with Holocene North Atlantic ice-rafting cold events. The coral composition clearly changed before and after the disturbances, with gradually reduced diversity resulting in a reef dominated by acroporiid coral. These data led to the hypothesis that coral reef growth was interrupted by suborbital millennial-scale global climate change induced by persistent solar activity during the Holocene in high-latitude coral reefs, such as those in the Northwest Pacific, leading to low diversity in the reefs that experienced each disturbance. Our results may provide new insights into theories of past and future coral reef formation worldwide.