Relating sediment impacts on coral reefs to watershed sources, processes and management: a review

Bartley, Rebecca, Bainbridge, Zoe T., Lewis, Stephen E., Kroon, Frederieke J., Wilkinson, Scott N., Brodie, Jon E., and Silburn, D. Mark (2014) Relating sediment impacts on coral reefs to watershed sources, processes and management: a review. Science of the Total Environment, 468-469. pp. 1138-1153.

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Abstract

Modification of terrestrial sediment fluxes can result in increased sedimentation and turbidity in receiving waters, with detrimental impacts on coral reef ecosystems. Preventing anthropogenic sediment reaching coral reefs requires a better understanding of the specific characteristics, sources and processes generating the anthropogenic sediment, so that effective watershed management strategies can be implemented. Here, we review and synthesise research on measured runoff, sediment erosion and sediment delivery from watersheds to near-shore marine areas, with a strong focus on the Burdekin watershed in the Great Barrier Reef region, Australia. We first investigate the characteristics of sediment that pose the greatest risk to coral reef ecosystems. Next we track this sediment back from the marine system into the watershed to determine the storage zones, source areas and processes responsible for sediment generation and run-off.

The review determined that only a small proportion of the sediment that has been eroded from the watershed makes it to the mid and outer reefs. The sediment transported > 1 km offshore is generally the clay to fine silt (< 4–16 μm) fraction, yet there is considerable potential for other terrestrially derived sediment fractions (< 63 μm) to be stored in the near-shore zone and remobilised during wind and tide driven re-suspension. The specific source of the fine clay sediments is still under investigation; however, the Bowen, Upper Burdekin and Lower Burdekin sub-watersheds appear to be the dominant source of the clay and fine silt fractions. Sub-surface erosion is the dominant process responsible for the fine sediment exported from these watersheds in recent times, although further work on the particle size of this material is required. Maintaining average minimum ground cover > 75% will likely be required to reduce runoff and prevent sub-soil erosion; however, it is not known whether ground cover management alone will reduce sediment supply to ecologically acceptable levels.

Item ID: 32093
Item Type: Article (Research - C1)
ISSN: 1879-1026
Keywords: Burdekin, Great Barrier Reef, land management, soil erosion, water quality
Funders: Queensland Department of Environment and Resource Management (Reef Policy Unit), CSIRO Water for a Healthy Country Flagship Program
Date Deposited: 19 Jun 2014 01:35
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050204 Environmental Impact Assessment @ 50%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050209 Natural Resource Management @ 50%
SEO Codes: 96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960504 Ecosystem Assessment and Management of Farmland, Arable Cropland and Permanent Cropland Environments @ 50%
96 ENVIRONMENT > 9605 Ecosystem Assessment and Management > 960507 Ecosystem Assessment and Management of Marine Environments @ 50%
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