2. Two fully-factorial mesocosm experiments (one for each crayfish pair) were used to investigate crayfish diet, and their impact on benthic invertebrate community structure, benthic algal standing stock and leaf litter decomposition rates, in allopatric and sympatric populations, compared to a crayfish free control. We used stable isotope analysis to examine crayfish diet in the mesocosms and in allopatric populations of each species in the Thames catchment.3. Isotopic niche width did not vary significantly between allopatric and sympatric populations of crayfish pairs in the mesocosms and isotopic niche partitioning in all the wild populations suggests the invaders can coexist.4. All four species altered benthic invertebrate community structure but with differing functional effects, often mediated via trophic cascades. Red swamp crayfish predation upon snails evidently promoted benthic algal standing stock via reduction in grazing pressure. However, a trophic cascade whereby the crayfish consumed native invertebrate shredders, causing a reduction in net leaf litter decomposition, was decoupled by red swamp and signal crayfish since they consumed leaf litter directly and thus moderated the cascade to a trickle when in sympatry with Turkish or virile crayfish, respectively. 6. Our results suggest that the combined effect of multiple invasions on the ecosystem can reflect either an additive effect of their independent impacts, or an amplified effect, which is greater than the sum of their independent impacts. A lack of general pattern in their effects makes any potential management strategy more complex.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.