Abstract: The morphological change of bivalve mollusk is believed to be an adaptation to environmental change, but the adaptation mechanism under different environmental conditions may differ. Corbicula fluminea (Müller, 1774) is a benthic bivalve native to South and East Asia and a dominant invasive species in many aquatic environments globally. In this paper, specimens of  C. fluminea  were collected  along a transect crossing the major watersheds of China, including the Yellow, Huaihe, Hanshui, Yangtze, and Xijiang Rivers, with the morphometry studied, aimed to understand the regional change of  C.fluminea shell morphology and its affecting factors. In the upstream tributaries of the Yangtze and Xijiang Rivers, which were located in the mountainous regions of western China, the C. fluminea shell was relatively long, low, and thin; while in the lower reaches of Yellow river, upstream tributaries of Huai River and Hanshui River, and middle and lower reaches of Xijiang River, which were located in the hilly areas or plains in the south and east China, the shell was relatively short, high, and thick. These changes revealed the adaptation of the clam to the changes of water current rate. The large contrast of topography created high flow rate in mountainous regions, where the clam evolved to become longer, lower, and thinner so as to resist the involuntary displacement by high flow rate water current; while the slow flow rate in the plains or low mountain areas encouraged the shell morphology to become relatively short and round. The changes of water temperature and water chemistry (mainly Ca²⁺ and K⁺ concentrations) had little effects on the shell morphometry. These results not only provided insight into the adaptation mechanism of clams to environmental change, but also helped guiding the cultural practices of C. fluminea in China.

Key words: Arbuscular mycorrhiza (AM), Biotechnology, Agriculture, Ecology