Differential vulnerability of native and non-native mollusks to predation by juvenile black carp

Black carp (Mylopharyngodon piceus), a large molluscivorous cyprinid native to eastern Asia, has become established in the Mississippi River basin in North America. The vulnerability of most North American snails and bivalves to black carp predation remains unknown, especially as it relates to juvenile black carp transitioning to mollusk prey. We conducted feeding experiments to assess the relative vulnerability of different mollusks to predation by age-0 and age-1 black carp. Age-0 black carp were tested with the North American native unionid Hamiota perovalis, a native pleurocerid snail Elimia livescens, and a native physid snail in the genus Physella. Age-1 black carp were tested with Elimia livescens, the North American native unionids Lampsilis cardium and Lampsilis cariosa, a native sphaeriid clam in the genus Musculium, and the non-native cyrenid clam Corbicula fluminea. Juvenile black carp readily attacked and consumed mollusks, but differences in vulnerability were evident among prey taxa exposed to age-0 and age-1 black carp. Age-0 black carp were able to consume Physella approaching the extent of their mouth gape. Age-1 black carp displayed greater feeding capabilities than age-0 black carp and easily consumed Elimia, Lampsilis, and Musculium. The only prey taxon that age-1 black carp struggled to consume was Corbicula, which had the thickest and widest shells relative to predator gape of all prey tested. Our results suggest that a wide range of small or juvenile mollusks are susceptible to predation by juvenile black carp but highlight that prey-specific characteristics, such as shell strength and shell size, may drive differential predation pressure on mollusk populations as the invaded range of black carp expands.