New insights into the food web of an Australian tropical river to inform water resource management

Leah S. Beesley, Bradley J. Pusey, Michael M. Douglas, Daniel C. Gwinn, Caroline A. Canham, Chris S. Keogh, Oliver P. Pratt, Mark J. Kennard, Samantha A. Setterfield

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    Abstract

    Rivers around the world are threatened by altered flow due to water resource development. Altered flow can change food webs and impact riverine energetics. The Fitzroy River, in northern Australia, is targeted for development but uncertainty remains about the sources of carbon supporting the food web, particularly in the lowlands—the region most likely to be impacted by water extraction. This study used stable isotopes to investigate if algal biofilm is the main carbon source sustaining fish in lowland habitats. We also sought evidence that large-bodied migratory fish were transporting remote carbon around the system. Our results revealed that local algal biofilm carbon was the dominant source of energy sustaining fish in wet season floodplain habitats, but that fish in main-channel pools during the dry season were increasingly dependent on other carbon sources, such as leaf litter or phytoplankton. We found no evidence that large-bodied fish were transporting remote carbon from the floodplain or estuary into the lower main-channel of the river. We recommend that water planners take a precautionary approach to policy until sufficient food web evidence is amassed.

    Original languageEnglish
    Article number14294
    Pages (from-to)1-12
    Number of pages12
    JournalScientific Reports
    Volume10
    Issue number1
    DOIs
    Publication statusPublished - 1 Dec 2020

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    Beesley, L. S., Pusey, B. J., Douglas, M. M., Gwinn, D. C., Canham, C. A., Keogh, C. S., Pratt, O. P., Kennard, M. J., & Setterfield, S. A. (2020). New insights into the food web of an Australian tropical river to inform water resource management. Scientific Reports, 10(1), 1-12. [14294]. https://doi.org/10.1038/s41598-020-71331-0