Laboratory based feeding behaviour of the Chinese mitten crab, Eriocheir sinensis, (Crustacea: Decapoda, Brachyura, Varunidae): fish egg consumption

摘要

Dispersal of Eriocheir sinensis from its native habitat is a worldwide concern. As one of the most invasive species known, this crab causessignificant disruption to foreign ecosystems. In particular, populations in the United Kingdom (UK) are increasing in number and E. sinensishas been reported from many river catchments. The ecological implications of this invasion are not fully understood. One aspect of concernlies in the potential for mitten crabs to predate fish eggs which, if realistic, could contribute to the decline of riverine populations. In thisstudy, 100 mitten crabs from the River Thames were used in experimental feeding trials to 1) investigate foraging ability on a variety of fisheggs and 2) establish whether crab size affected foraging potential. Eggs ranged from 1–6 millimetres (mm) in diameter from one of fourspecies of marine and freshwater fish; zebrafish, lumpfish, Pacific salmon and trout. Predation by crabs varied with egg type; crabs werecapable of foraging 1mm zebrafish eggs, but the majority consumed eggs 2–6mm in diameter. The most attractive eggs were apparentlylumpfish, where the median proportion consumed was 100%. Crab size did not appear to govern foraging potential, though variation wasobserved in the size range of juvenile crabs consuming the different eggs with the largest, salmon, being consumed by crabs of the broadestsize range. E. sinensis does have the potential to predate on a range of fish eggs, and the results are used to infer the risk presented to specificgroups of UK fish stocks.Key words: invasive brachyuran, foraging, carapace size, fish eggs