Effects of intrapopulation phenotypic traits of invasive crayfish on leaf litter processing

Abstract

The impact of invasive alien species (IAS) on an ecosystem is primarily studied at the species level, whereas the functional impacts of their genetic and phenotypic traits are poorly investigated. We used two laboratory based experiments to assess how intrapopulation phenotypic traits (size, sex, and number of claws) of the invasive red swamp crayfish Procambarus clarkii affect invertebrate shredders and leaf processing. Leaf consumption was significantly affected by the size and number of claws but not by the sex of the crayfish. Bigger animals presented a higher overall consumption but, in contrast, the mass of leaves consumed per unit crayfish body mass decreased with size. Indeed, the production of particulate organic matter followed the same trend, suggesting that the higher metabolic needs of smaller animals are responsible for their higher feeding activity on leaf litter. Claw loss in P. clarkii also led to increased leaf consumption and may be related to increased energy requirements for claw regeneration. Our results highlight the importance of also considering the phenotypic traits within populations for better understanding the impacts of IAS on ecosystem processes.