Effects of sustained predation by fast‐growing transgenic common carp (Cyprinus carpio Linnaeus, 1758) on gastropods in artificial environments

The present study addressed the effects of growth hormone‐transgenic and non‐transgenic common carp (Cyprinus carpio L.) predation on the community and populations of four gastropod species cultured in artificial environments. After a 110‐day population‐based predation experiment (three replicate pools [16 m²] for each genotype with one fish [total length 45.0~51.4 cm] and 150 Bellamya aeruginosa (Reeve 1863) per pool), there were no significant effects of predation by either transgenic or non‐transgenic carp on the biomass, number, or size selectivity of the population. Following a 10‐day community‐based predation experiment (three replicate pools [16 m²] for each genotype with one fish [total length 45.0~50.5 cm] and 150 Alocinma longicornis (Benson 1842), 100 Parafossarulus sinensis (Neunayr 1883), 55 B. aeruginosa, and 33 Radix auricularia L. per pool), the consumption rate and the number of gastropods predated by transgenic carp were 2.60 times and 2.85 times higher, respectively, than those of non‐transgenic carp. Furthermore, the biomass of A. longicornis, P. sinensis and B. aeruginosa consumed by transgenic carp was significantly (p < .05) higher than that by non‐transgenic carp. There was a significant difference in the type selection of the four gastropods by the transgenic and non‐transgenic carp, but both predators preferred R. auricularia and avoided B. aeruginosa. Compared with the non‐transgenic carp, predation by transgenic carp resulted in a significant decrease in A. longicornis (p < .05) and an increase in B. aeruginosa (p < .05). These results indicate that the effects of predation by both transgenic and non‐transgenic carp on the B. aeruginosa population tend to be similar, but their effects on the community composed of the four gastropods were significant different. This information may be useful for assessing the environmental risk of transgenic carp.