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Type: Journal article
Title: Impact of a drought on nutrient concentrations in the Lower Lakes (Murray Darling Basin, Australia)
Author: Aldridge, K.
Lamontagne, S.
Deegan, B.
Brookes, J.
Citation: Inland Waters, 2011; 1(3):159-176
Publisher: Freshwater Biological Association
Issue Date: 2011
ISSN: 2044-2041
Statement of
Kane Thomas Aldridge, Sébastien Lamontagne, Brian Martin Deegan and Justin Dean Brook
Abstract: Nutrient concentrations increased in 2 lakes (Lake Alexandrina and Lake Albert) located at the downstream end of the Murray Darling Basin, Australia, as a result of water level drawdown and salinisation associated with a severe drought. Between January 2007 and March 2008 the salinity difference between the inlet and outlets (5 barrages) increased from 0.9 to 21.0 g L-1, resulting primarily from seawater leakage through the barrages. Subsequently, in relatively sheltered areas upstream of the barrages, permanent salinity-derived density stratification developed, leading to the development of an anoxic hypolimnion. This seemingly favoured the regeneration of dissolved nutrients from the sediments, with standing stocks of ammonium and filterable reactive phosphorus increasing by 250 and 142%, respectively. However, the source of leakage water through the barrages also contributed to the increase. While dissolved organic carbon concentrations also increased, this was a result of evapoconcentration because calculated standing stocks changed little during the study period. In the open water areas, vertical density stratification was not evident, but sediment resuspension seemed to increase during the drawdown. Total organic nitrogen and total phosphorus concentrations were closely related to light attenuation, suggesting increased resuspension of particulate nutrients during the water level drawdown or increased assimilation of dissolved nutrients by phytoplankton. Overall, sediment resuspension seemed to have had a greater impact on nutrient concentrations in open water areas of Lake Alexandrina and Lake Albert, while saline intrusions were more significant in relatively sheltered areas located close to the lake outlets.
Rights: © All content copyright FBA & SIL 2011
RMID: 0020116712
DOI: 10.5268/IW-1.3.409
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Appears in Collections:Earth and Environmental Sciences publications
Environment Institute publications
Environment Institute Leaders publications

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