Distribution, Growth, and Competitive Impacts of the Exotic Chinese Mystery Snail (Bellamya Chinensis) in the James River, Southwest Missouri

The exotic Chinese mystery snail (Bellamya chinensis) is a large viviparid capable of inhabiting both lakes and streams. Following the 2006 discovery of a population in the Missouri Ozarks, I surveyed 28 depositional areas in the lower James River in 2008. Two of 28 sites were positive for B. chinensis, and densities were low (average 0.18 m-2). I collected nine adult B. chinensis as brood stock for laboratory cultures, removed newborn offspring, and marked 54 individuals for growth rates. The adult B. chinensis produced 10.5 offspring snail-1 month-1. Over a two month period the juveniles increased their shell length by 0.1 mm day-1. A food preference study with B. chinensis and the native pulmonate Physa gyrina indicated a broad overlap in diet, with both species preferring periphyton-encrusted rocks. A resource competition experiment between juvenile P. gyrina (four individuals per 500 mL jar) and B. chinensis used an additive design (0, 1, 2, 3, or 4 B. chinensis per jar). Decreased growth rates of P. gyrina with increasing B. chinensis densities were consistent with effects of competition. Lakes or streams with high densities of exotic B. chinensis could see a reduction in native snails through competitive exclusion