On the underappreciated role of scavengers in freshwater ecosystems

Abstract

The role of scavengers is well understood in terrestrial and marine systems but less so in freshwater ecosystems. We synthesized existing knowledge of scavenger ecology in freshwater, particularly within the context of the Anthropocene, including the patchy distribution of carrion, consumer responses, competition, and transfer of energy, nutrients, and diseases. We also explored ecosystem services provided by freshwater scavengers, such as direct material benefits and improvements in water quality. In addition, we examined how human activities-such as climate change, disturbance, exploitation, and fragmentation-are affecting scavenger behavior and abundance. To mitigate these anthropogenic impacts, we identified management options for environmental practitioners and decision-makers, emphasizing the importance of integrating freshwater scavenger roles into management plans and providing adequate policy protections. Finally, we highlighted key knowledge gaps, particularly regarding how changes in scavenger populations and their food sources may alter ecosystem structure and function.

Keywords: aquatic ecosystems; aquatic subsidy; carrion ecology; scavenging.

Figure 1.

Freshwater scavengers are a diverse group across many taxa and habitat types: (a) Common yabby (Cherax destructor) feed on carrion in swamps, streams, and rivers within Australia. (b) Corydoras catfish (Corydoras melanotaenia) occur in lotic habitats throughout South America, (c) herring gull (Larus  smithsonianus) inhibit many aquatic habitats throughout North America, (d) snapping turtles (Chelydra serpentina) are located throughout North America in slow moving waters including wetlands and ponds, and (e) European mink (Mustela lutreola) are found in lotic and lentic habitats.