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.

Combined per‐capita and abundance effects of an invasive species on native invertebrate diversity and a key ecosystem process

“…The presence and increasing abundance of the invasive crayfish P. leniusculus had a strong negative effect on native invertebrate abundance. Similar results have been described (Twardochleb et al, 2013), but the effects appear to vary between populations at different streams (Evangelista et al, 2019;Klose & Cooper, 2012) or within populations among different traits (Carvalho et al, 2018). Invertebrate abundance was lower at high crayfish abundance sites in cages without the crayfish indicating higher predation impacts on invertebrate diversity in highly invaded areas.…”

“…The impacts of IAS may vary spatially and temporally depending on important factors, such as population density (Benkwitt, 2015;Pintor et al, 2009), phenotypic diversity (Carvalho et al, 2018), propagule pressure (Barney et al, 2016;Warren et al, 2012), functional distinctiveness (Ehrenfeld, 2010;Sousa et al, 2011) and environmental characteristics of the invaded area (Strayer et al, 2006).…”

“…The impacts of IAS may vary spatially and temporally depending on important factors, such as population density (Benkwitt, 2015; Pintor et al., 2009), phenotypic diversity (Carvalho et al., 2018), propagule pressure (Barney et al., 2016; Warren et al., 2012), functional distinctiveness (Ehrenfeld, 2010; Sousa et al., 2011) and environmental characteristics of the invaded area (Strayer et al., 2006). However, the invasion process (e.g., establishment, population growth, dispersion or niche occupation) may be context‐dependent and perhaps change through time as a consequence of evolutionary responses by native species, increasing the unpredictability of IAS impacts (Buckley, 2017; Mooney & Cleland, 2001).…”

Non-native freshwater fauna in Portugal: A review

“…This represents more than one million euros of damage per year at the national scale. Studies addressing impacts of the red swamp crayfish also encompassed examples demonstrating negative effects on plants and algae (Anastácio et al, 2000;Barradas et al, 2006), aquatic macroinvertebrates (Banha and Anastácio, 2011;Correia and Anastácio, 2007;Correia et al, 2005), amphibians (Cruz and Rebelo, 2005;Cruz et al, 2006;Cruz et al, 2008;Nunes et al, 2010;Nunes et al, 2013), decomposition processes (Carvalho et al, 2016(Carvalho et al, , 2018) and water quality (Anastácio et al, 2005b). Despite this, the species became an abundant food source for several native predators (Correia, 2001) and is also captured for commercial purposes, being mostly exported to processing units in southern Spain (Gutiérrez-Yurrita et al, 1999;Souty-Grosset et al, 2016).…”

Substrate mediated predator–prey interactions between invasive crayfish and indigenous and non-native amphipods

“…Crayfish represent one of the most widely translocated groups of freshwater organisms globally (Gallardo et al, 2016), and where populations have successfully become established, they may have detrimental effects on all trophic levels associated with their polytrophic and omnivorous feeding habits (Dorn and Wojdak, 2004;Carvalho et al, 2018). Crayfish are keystone species and can dominate benthic biomass where they occur in both lentic and lotic ecosystems (Momot, 1995;Crandall and Buhay, 2008).…”