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.

人类正在通过退化淡水生态系统来增加鱼类死亡的频率。与此同时，像淡水龟这样的食腐动物在全球范围内正在减少，包括澳大利亚墨累-达令盆地。减少清除可能会导致影响生态系统和人类的水质问题。我们使用野外和中观实验来测试海龟的食腐是否在模拟鱼类死亡期间调节水质。在野外，我们发现海龟是鱼腐肉的重要清道夫。在中层世界中，海龟迅速消耗腐肉，并且与没有海龟的对照相比，有海龟的中层世界中的水质更快地恢复到鱼被杀死前的水平。我们的实验具有重要的生态意义，因为它们表明海龟是调节淡水生态系统水质的重要清道夫。