Invasive alien shredders clear up invasive alien leaf litter.

Area of Science:

• Ecology
• Environmental Science
• Invasive Species Biology

Background:

• Biological invasions can profoundly alter ecosystem processes.
• Invasive riparian plants introduce leaf litter to freshwater, potentially impacting food webs.
• Invasive alien decapod crustaceans are known to consume leaf litter.

Purpose of the Study:

• To investigate the consumption and breakdown of invasive leaf litter by invasive decapod crustaceans.
• To compare the processing rates of invasive leaf litter by invasive decapods versus indigenous crayfish.
• To understand the implications of these interactions for freshwater ecosystem functioning.

Main Methods:

• Experimental setup comparing leaf litter breakdown by signal crayfish (Pacifastacus leniusculus) and Chinese mitten crabs (Eriocheir sinensis) against indigenous white-clawed crayfish.
• Quantification of leaf litter decomposition rates and analysis of secondary organic matter production.
• Assessment of changes in decapod body mass in response to consuming different leaf litter types, including invasive Rhododendron ponticum.

Main Results:

• Invasive signal crayfish and Chinese mitten crabs processed invasive leaf litter, including R. ponticum, more effectively than indigenous crayfish.
• Leaf litter species influenced secondary product generation, with more fine particulate organic matter from less palatable alien litter.
• Decapod body mass changes varied, with P. leniusculus showing less mass loss on R. ponticum, and E. sinensis losing mass on A. pseudoplatanus.

Conclusions:

• Invasive alien decapods can effectively break down invasive riparian plant litter, potentially mitigating detritus accumulation in freshwaters.
• These findings highlight complex interspecific feedbacks between invasive plants and animals.
• A nuanced consideration of both positive and negative feedbacks is crucial for understanding and managing biological invasions.