Managing wetlands as off-river storages: impacts on zooplankton communities
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The competing demands of the environment and agriculture has challenged managers of waterways and prompted the development of new and novel ways of providing water for consumptive use without compromising the aquatic ecosystem. One partial remedy that has been proposed involves using wetlands as intermediary off-river storages to achieve consumptive benefits whilst maintaining ecological values. This study assessed the suitability of such a strategy by examining the impact of artificial drawdown on wetland zooplankton communities. An experiment was undertaken in outdoor mesocosms in which two treatments were compared over a 109-day duration: (1) partial artificial drawdown—where approximately half of the water was siphoned out after 42 days; and (2) natural drawdown—where the water was left to drawdown naturally via evaporation. Artificial drawdown only caused a small acceleration (<4 weeks) in the decline of abundance and density associated with natural population fluctuations, and temporarily changed the community structure. Furthermore, it had no effect on taxon richness, community composition and the initiation of dormancy. This suggests that wetlands could potentially be used for supporting consumptive demands whilst still maintaining abundant and diverse zooplankton communities, and hence a suitable food supply for higher order consumers such as fish and waterfowl.
KeywordsRiver regulation Water sharing Dormancy Drawdown
The authors wish to thank Catherine McInerney, Rochelle Petrie, Matthew Vogel, Danielle Smith and Simon Maffei for assistance with setting up the mesocosms, sampling and sample processing. We also thank The University of Melbourne, Dookie Campus, for their support in obtaining the sediment used in the mesocosms, and Wonga Wetlands, Albury, for the use of their facilities during the mesocosm experiment. This project was part of the larger Farms, Rivers and Markets Project, which is an initiative of Uniwater and funded by the National Water Commission, the Victorian Water Trust, The Dookie Farms 2000 Trust (Tallis Trust) and The University of Melbourne. The Farms, Rivers and Markets Project is supported by the Departments of Sustainability and Environment and Primary Industry, the Goulburn Broken Catchment Management Authority and Goulburn-Murray Water.
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