© 2020, The Author(s). Humans are increasing the frequency of fish kills by degrading freshwater ecosystems. Simultaneously, scavengers like freshwater turtles are declining globally, including in the Australian Murray–Darling Basin. Reduced scavenging may cause water quality problems impacting both ecosystems and humans. We used field and mesocosm experiments to test whether scavenging by turtles regulates water quality during simulated fish kills. In the field, we found that turtles were important scavengers of fish carrion. In mesocosms, turtles rapidly consumed carrion, and water quality in mesocosms with turtles returned to pre-fish kill levels faster than in turtle-free controls. Our experiments have important ecological implications, as they suggest that turtles are critical scavengers that regulate water quality in freshwater ecosystems. Recovery of turtle populations may be necessary to avoid the worsening of ecosystem health, particularly after fish kills, which would have devastating consequences for many freshwater species.
We thank Paiwalla and Riverglades Communities in South Australia, and the owners of Hawkesview in New South Wales, for their support. We thank Murray Bridge NRM and S. O'Sullivan at the University of South Australia for lending traps and equipment, as well as R. Shine and Z. M. Grootendorst for helpful comments on the manuscript. We thank the Nature Foundation South Australia for supporting our field project. We also thank ARC Linkage grant LP140100011 partners: Department of Environment and Primary Industries, Foundation for National Parks and Wildlife, Yorta Yorta Nation Aboriginal Corporation, North Central Catchment Management Authority, Save Lake Bonney Group Inc. and Winton Wetlands Committee of Management Inc.
Paiwalla Community in South Australia
Riverglades Community in South Australia
ARC Linkage grant: Department of Environment and Primary Industries | LP140100011
ARC Linkage grant: Foundation for National Parks and Wildlife | LP140100011
ARC Linkage grant: Yorta Yorta Nation Aboriginal Corporation | LP140100011
ARC Linkage grant: North Central Catchment Management Authority | LP140100011
ARC Linkage grant: Save Lake Bonney Group Inc. | LP140100011
ARC Linkage grant: Winton Wetlands Committee of Management Inc. | LP140100011
Nature Foundation South Australia
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