Freshwater impacts in the central Great Barrier Reef: 1648–2011

Lough, J.M., Lewis, S.E., and Cantin, N.E. (2015) Freshwater impacts in the central Great Barrier Reef: 1648–2011. Coral Reefs, 34 (3). pp. 739-751.

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The Australian summer monsoon is highly variable from year to year resulting in high variability in the magnitude and extent of freshwater river flood plumes affecting the Great Barrier Reef (GBR). These flood plumes transport terrestrial materials and contaminants to the reef and can have significant impacts on both water quality and ecosystem health. The occurrence and intensity of these freshwater flood plumes are reliably recorded as annual luminescent lines in inshore massive corals and occasional luminescent lines in mid-shelf corals. We use measured luminescence in a long Porites core and four recently collected short cores from Havannah Island (a nearshore reef in the central GBR) to reconstruct Burdekin River flow, 1648–2011, and five recent short cores from Britomart Reef (a mid-shelf reef, 65 km northeast of Havannah Island) to assess the frequency of flood plume events extending beyond the inshore to mid-shelf reefs. The reconstruction highlights that the frequency of high flow events has increased in the GBR from 1 in every 20 yr prior to European settlement (1748–1847) to 1 in every 6 yr reoccurrence (1948–2011). Three of the most extreme events in the past 364 yr have occurred since 1974, including 2011. The reconstruction also shows a shift to higher flows, increased variability from the latter half of the nineteenth century, and likely more frequent freshwater impacts on mid-shelf reefs. This change coincided with European settlement of northern Queensland and substantial changes in land use, which resulted in increased sediment loads exported to the GBR. The consequences of increased sediment loads to the GBR were, therefore, likely exacerbated by this climate shift. This change in Burdekin River flow characteristics appears to be associated with a shift towards greater El Niño–Southern Oscillation variability and rapid warming in the southwest Pacific, evident in independent palaeoclimatic records.

Item ID: 43397
Item Type: Article (Research - C1)
ISSN: 1432-0975
Keywords: luminescence; river flow; Great Barrier Reef; freshwater
Date Deposited: 18 Mar 2016 02:46
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050205 Environmental Management @ 35%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040605 Palaeoclimatology @ 35%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040608 Surfacewater Hydrology @ 30%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960304 Climate Variability (excl. Social Impacts) @ 100%
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