Prioritising Non-Native Crayfish Species for Management in the Rhine-Main Observatory Using the Dispersal-Origin-Status-Impact (DOSI) Scheme.

Abstract

Managing non-native species remains a critical challenge in biodiversity conservation, highlighting the need for effective prioritisation frameworks that integrate ecological, economic and policy considerations. Given that biological invasions are a population-level rather than a species-level phenomenon, more nuanced assessment schemes are needed. The Dispersal-Origin-Status-Impact (DOSI) scheme is such an example. Using the Rhine-Main-Observatory (RMO) Long-Term Ecological Research (LTER) site in Germany as a model system, we applied DOSI to rank the occurring non-native crayfish species to guide conservation actions. Our results classify the signal crayfish Pacifastacus leniusculus as the highest priority for management due to its expanding range, autonomous spread and severe ecological and economic impacts. The spiny-cheek crayfish Faxonius limosus follows as a medium-high priority species, while the red swamp crayfish Procambarus clarkii and the calico crayfish Faxonius immunis are ranked lower due to their shrinking or static populations despite their known potential impacts observed at other places. Our study highlights the utility of DOSI as a practical and scalable tool for invasion risk assessment, offering a targeted, data-driven approach to inform decision-making at the population level. By shifting the focus to population-level management, DOSI enhances conservation planning beyond traditional species-based assessments, providing a structured framework for mitigating the risks posed by invasive species in dynamic freshwater ecosystems.