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Retention time as a primary determinant of colour and light attenuation in two tropical Australian reservoirs

Townsend, Simon A., Luong-Van, Jim T. and Boland, Kevin (1996). Retention time as a primary determinant of colour and light attenuation in two tropical Australian reservoirs. Freshwater Biology,36(1):57-69.

Document type: Journal Article
Citation counts: Scopus Citation Count Cited 19 times in Scopus Article | Citations

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Title Retention time as a primary determinant of colour and light attenuation in two tropical Australian reservoirs
Author Townsend, Simon A.
Luong-Van, Jim T.
Boland, Kevin
Journal Name Freshwater Biology
Publication Date 1996
Volume Number 36
Issue Number 1
ISSN 0046-5070   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-0030304850
Start Page 57
End Page 69
Total Pages 13
Place of Publication United Kingdom
Publisher Wiley-Blackwell Publishing Ltd.
Field of Research BIOLOGICAL SCIENCES
Abstract 1. The light climates of Darwin River Reservoir (DRR) and Manton River Reservoir (MRR), in northern Australia, are compared for an 8-year period. The reservoirs are subject to the same wet/dry tropical climate and have similar catchment characteristics, but differ in their basin morphology, retention time and trophic status.

2. Median euphotic depths in DRR and MRR were 9.7 and 4.4 m, respectively. Seasonal variation in each reservoir’s euphotic depth was best explained by colour, based on a stepwise linear regression. Turbidity was excluded from the two regressions, while chlorophyll a concentration was significant only for the MRR regression.

3. Both reservoirs showed the same seasonal pattern for colour. Wet season inflow increased reservoir colour, and was followed by a reduction in colour due to photodegradation and microbial decomposition of humic material, reaching a minimum before the next wet seasons inflow.

4. Although the colour of catchment run-off into both reservoirs was similar, MRR colour was two to three times greater than that measured in DRR. The higher colour and greater light attenuation of MRR is attributed primarily to its shorter retention time, and therefore shorter time for colour removal. Annual retention time accounted for 97% of the variability of average annual colour (measured as absorption at 440 nm), based on a linear regression of log10 transformed data for both reservoirs.

5. Long retention times favour reduced colour, increasing water transparency, particularly in water bodies of low trophic state and inorganic turbidity.
DOI http://dx.doi.org/10.1046/j.1365-2427.1996.00072.x   (check subscription with CDU E-Gateway service for CDU Staff and Students  check subscription with CDU E-Gateway in new window)
 
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Created: Fri, 29 Aug 2014, 20:17:14 CST by Anthony Hornby