NOAA/WDS Paleoclimatology - Great Keppel Island, Great Barrier Reef Trace Metal Data from 1958-2010 CE

Extensive catchment modification since European settlement in the eastern coast of Australia results in poor coastal water quality, which poses a major threat for near shore coral communities in the iconic Great Barrier Reef (GBR). This study investigated coastal water quality over the period of 1958 to 2010 using monthly resolution Ba/Ca and Y/Ca signatures obtained from Porites sp. coral from Great Keppel Island, southern GBR, Australia. Geochemical proxy records were influenced by environmental change on a seasonal to decadal scale. Although seasonal oscillations of Ba/Ca and Y/Ca were related to rainfall and discharge from the Fitzroy River catchment, some uncorrelated anomalous peaks were evident throughout the time series. Regardless, the behaviour of these proxies was significantly consistent over the longer time scale. A long term drought-breaking flood resulted in significant increase in the targeted elemental ratios owing to higher terrigenous sediment influx to the near shore marine environment from a catchment with reduced groundcover. Following this intense flashing event, elemental ratios were reduced in subsequent wet periods as a result of less sediment being available for transport. Our geochemical proxy record highlights the impact of terrestrial runoff on inshore water quality and the coral community of the southern GBR.