Flexible prey handling, preference and a novel capture technique in invasive, sub-adult Chinese mitten crabs

Abstract

Eriocheir sinensis (Crustacea: Brachyura: Varunidae) is one of only two crabs on the world's list of 100 most invasive aquatic invertebrates. This crab has successfully invaded NE Europe as well as the United States, eastern Canada, southern Iraq and Tokyo Bay, Japan. In England, the River Thames population of E. sinensis continues to increase in numbers and disperse westward upstream, although little is known about foraging. The present study undertook a preference and prey handling study of sub-adult mitten crabs collected from the Thames. A digital camcorder, capable of detecting infrared light, was used in the laboratory overnight to identify crab food preference, document prey handling times and record behaviour. The test prey species, namely the amphipod Gammarus zaddachi, and two species of gastropod molluscs, Theodoxus fluviatilis and Radix peregra, were collected in the same habitat as the crabs, and all were consumed under laboratory conditions. Eriocheir were able to capture mobile G. zaddachi using a novel prey capture technique not previously described in brachyurans and use different skills for handling each prey species. This flexibility in prey handling may be an important contributory factor in their freshwater invasive capacity. Results indicated that the crabs had a preference for G. zaddachi which were consumed most frequently and preferentially over both mollusc species. Prey choice may be based on maximising net energy gain as consuming G. zaddachi was shown to provide the highest rate of potential energy consumption by the crab due, in part, to a much shorter handling time than for both species of snails.

Predatory impacts of alien decapod Crustacea are predicted by functional responses and explained by differences in metabolic rate

“…obs. ; Mills et al 2016). In the field, strong predation pressure from E. sinensis whether prey are abundant (small h) or rare (large a) could lead to prey population decline or extinction.…”

To invade or not to invade? Exploring the niche-based processes underlying the failure of a biological invasion using the invasive Chinese mitten crab

“…Outside its native range, E. sinensis is considered an invasive species that has successfully established breeding populations in Europe and North America (Brockerhoff and McLay, 2011;Dittel and Epifanio, 2009;Herborg et al, 2003). Previous studies have demonstrated the negative impacts of this invasive species in introduced regions, including predation on native species (Mills et al, 2016;Rosewarne et al, 2016;Rudnick and Resh, 2005;Webster et al, 2015;Wójcik et al, 2015), competition with native organisms (Gilbey et al, 2008;Zhang et al, 2019b), pathogen transmission (Schrimpf et al, 2014), and riverbank erosion (Dittel and Epifanio, 2009). Multiple introduction vectors are blamed for the transportation of E. sinensis into new habitats, including ballast water discharge, the live crab trade, and religious animal release practices (Cohen and Carlton, 1997;Dittel and Epifanio, 2009;Low et al, 2013).…”

Experimental predatory behavior of the stone crab Eriphia verrucosa (Forskål, 1775) (Decapoda, Brachyura, Eriphiidae)

“…When they feed on these hard-shelled preys, many crabs are capable of extracting the meat by peeling the shell aperture and thus avoid spending more time and energy in shell crushing (Rossi and Parisi, 1973). Besides this specialization, there are also reports of more generalized behavior in crab feeding, such as a widespread preference for feeding on small-size preys: these are presumably easier to manipulate and crush and hence offer higher net energy gains ( Juanes, 1992;Mills et al, 2016). It is therefore important to know the individual prey preference of crab predators in order to better understand their ecological effects on their prey populations and, as a result, on the assemblage composition of intertidal inhabitants.…”