McCulloch et al., 2003: 

"The effect of European settlement on water quality in the Great Barrier Reef of Australia is a long-standing and controversial issue^1–6. Erosion and sediment transport in river catchments in this region have increased substantially since European settlement^6–10, but the magnitude of these changes remains uncertain^1–10. Here we report analyses of Ba/Ca ratios in longlived Porites coral from Havannah Reef—a site on the inner Great Barrier Reef that is influenced by flood plumes from the Burdekin river—to establish a record of sediment fluxes from about 1750 to 1998. We find that, in the early part of the record, suspended sediment from river floods reached the inner reef area only occasionally, whereas after about 1870—following the beginning of European settlement—a five- to tenfold increase in the delivery of sediments is recorded with the highest fluxes occurring during the drought-breaking floods. We conclude that, since European settlement, land-use practices such as clearing and overstocking have led to major degradation of the semi-arid river catchments, resulting in substantially increased sediment loads entering the inner Great Barrier Reef."

"Figure 2 The coral Ba/Ca record of suspended sediment into the GBR by the Burdekin river over approximately the past 250 years. Barium provides a proxy for suspended sediments as it is desorbed from flood plume sediments²¹ and quantitatively partitioned into the corals, calcium carbonate skeleton²². a, Coral record from Havannah Reef (green line) for the period from 1760 to 1998 with Ba/Ca peaks proportional to the sediment flux delivered by Burdekin flood plume events. The frequency and intensity of flood events is indicated by luminescent bands in the coral skeleton ^19,20,28, represented here as major (black bar), average (blue bar) and small (grey bar) discharge events. The record of discharge for the Burdekin river, available from 1921, is also shown (black line). b, Coral record for the period from 1840 to 1990 showing the large increase in Ba/Ca that commences in 1870, the first major flood following European settlement. c, Coral records from Havannah (green line) and Pandora reefs (red line) for the period 1965 to 1985 show excellent agreement and a good correlation with the Burdekin river weekly discharge (black line)."

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Citation and/or URL

McCulloch, M., Fallon, S., Wyndham, T., Hendy, E., Lough J. and Barnes, D., 2003, Coral record of increased sediment flux to the inner Great Barrier Reef since European settlement, Nature 421: 727-730.

Spatial Coverage

 Central Great Barrier Reef

Temporal Coverage

 Pre-European to present

Update Frequency

 Not applicable 

Other Information

 None