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This paper reviews both the recent and longer-term (Holocene) ecological history of coral reefs in the South China Sea (SCS). (1) Local ecological monitoring since the 1960s shows that the coral reefs in the South China Sea have declined dramatically, reflecting the rapid decrease of living coral cover and the great loss of symbiotic zooxanthellae. Collectively, this has led to a significant decrease of annual CaCO production. Heavy anthropogenic activities and global warming are recognized as major triggers of the observed coral reef degradation. Observations show that the modern coral reefs in the SCS are a source of atmospheric CO in summer. (2) Coral reefs of the SCS have been widely used to reveal longer-term environmental variations, including Holocene high-resolution sea surface temperature (SST) and abrupt climate events, millennial-scale El Niño variations, millennial- and centennial-scale sea level oscillations, strong and cyclic storm activities, East Asian monsoon intensities, variation in seawater pH, and recent seawater pollution. (3) Coral reefs of the southern SCS have experienced repeated episodes of bleaching over the last 200 years due to high SST and intense El Niño events; coral reefs of the northern SCS suffered high levels of mortality during several abrupt winter cold-water bleaching events during the middle Holocene warm period. On average, recovery after the middle Holocene cold-bleaching took 20-30 years; recovery following other middle Holocene environmental stresses took approximately 10-20 years. Such findings have significantly contributed to the understanding of the present ecological pressures faced by the coral reefs in the SCS, the histories of Holocene climate/environment changes, and the long-term models of coral reef responses to various past environmental changes. [ABSTRACT FROM AUTHOR]

Numerous studies have been conducted on the evolutionary history of the Kuroshio Current (KC) and other extensions. However, the history of the KC intrusion into the South China Sea (SCS) through the Luzon Strait has been little studied. Here we trace the Holocene developmental history of the KC intrusion and its impact on environmental transformation in the northern SCS. This study involved a comprehensive analysis of planktonic foraminifera, clay minerals and geochemical elements of core 05E306 sediments from the northeastern SCS. AMS 14C dates indicated that the sedimentation rate at the core site was most rapid (>1000 cm/ka) before ~6.0 ka, relatively rapid (~65 cm/ka) between 6.0 and 4.6 ka and slow (~24 cm/ka) since 4.6 ka. The Pulleniatina minimum event (PME) occurred between 4.6 and 2.7 ka, together with high percentages of Neogloboquadrina dutertrei and Globorotalia menardii. Planktonic foraminifera indicated that the KC intrusion experienced three significant changes at 6.0, 4.6 and 2.7 ka in turn. Depositional environments, including input of terrigenous materials and development of biogenic materials, similarly underwent three important transformations at 6.0, 4.1 and 3.0 ka, respectively. Abrupt changes in sedimentary records at the study core are contemporary with records from the tropical Pacific during the Holocene. This indicates that development of the KC intrusion and its impact on depositional environments in the SCS can be correlated with tropical factors from the low-latitude oceans. [ABSTRACT FROM AUTHOR]

High-resolution Sr/Ca ratios of two Porites corals from Leizhou Peninsula were measured using inductively coupled plasma atomic spectrometry (ICP-AES). TIMS U-Th dating reveals that the life-spans of the two corals are 489–500 AD and 539–530 BC, respectively. Monthly sea surface temperatures (SSTs) during these two periods can be reconstructed from their skeletal St/Ca ratios. The results reveal that SSTs during 539–530 BC were roughly the same as those during 1990–2000 AD in this area, indicating a relative warm climate period. However, the period of 489–500 AD was significantly cooler, with annual mean SST, the 10-a average of minimum monthly winter SSTs and the 10-a average of maximum monthly summer SSTs being about 2, 2.9 and 1°C lower than that in the 1990s, respectively. Such climate patterns agree well with the phenological results recorded in the historic documents in other areas of China. [ABSTRACT FROM AUTHOR]

We present evidence of elevated Holocene sea levels on the north coast of Vietnam, comprising radiocarbon dating of raised coastal geomorphological and palaeobiological features at localities on the margins of the Bac Bo (Red River) Plain. This evidence indicates that by ca. 5500 cal yr B.P. mid-tide lay approximately 5.4 m above national datum, that is 3.25 m above present local mid-tide. By c. 3500 cal yr B.P., sea level was lowering and, by ca. 2000 cal yr B.P., mid-tide lay at or above 1.5 m above present local mid-tide. It is not yet possible to infer patterns of sea-level fluctuation other than an overall lowering of elevation, although the separation of the raised and modern erosion notches does suggest two dominant mid to late Holocene periods of erosion — probably periods of sea-level still-stand or relatively slow sea-level change. The intervening period of relatively rapid sea-level change and associated reduced erosion probably dates to after ca. 2000 cal yr B.P.. [ABSTRACT FROM AUTHOR]