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Mar Pollut Bull. 2014 Jul 15;84(1-2):191-200. doi: 10.1016/j.marpolbul.2014.05.012. Epub 2014 May 23.

The effects of river run-off on water clarity across the central Great Barrier Reef.

Author information

1
Australian Institute of Marine Science, PMB No. 3, Townsville, Queensland 4810, Australia. Electronic address: k.fabricius@aims.gov.au.
2
Australian Institute of Marine Science, PMB No. 3, Townsville, Queensland 4810, Australia.
3
Biophysical Oceanography Group, School of Geography, Planning and Environmental Management, University of Queensland, Brisbane 4072, Australia.
4
Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Queensland 4811, Australia.

Abstract

Changes in water clarity across the shallow continental shelf of the central Great Barrier Reef were investigated from ten years of daily river load, oceanographic and MODIS-Aqua data. Mean photic depth (i.e., the depth of 10% of surface irradiance) was related to river loads after statistical removal of wave and tidal effects. Across the ∼25,000 km(2) area, photic depth was strongly related to river freshwater and phosphorus loads (R(2)=0.65 and 0.51, respectively). In the six wetter years, photic depth was reduced by 19.8% and below water quality guidelines for 156 days, compared to 9 days in the drier years. After onset of the seasonal river floods, photic depth was reduced for on average 6-8 months, gradually returning to clearer baseline values. Relationships were strongest inshore and midshelf (∼12-80 km from the coast), and weaker near the chronically turbid coast. The data show that reductions in river loads would measurably improve shelf water clarity, with significant ecosystem health benefits.

KEYWORDS:

Generalized additive mixed models; Great Barrier Reef; Nutrient runoff; Photic depth; River floods; Turbidity

PMID:
24863415
DOI:
10.1016/j.marpolbul.2014.05.012
[Indexed for MEDLINE]
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