Simple Summary
The clam Meretrix meretrix (Linnaeus, 1758) is an important commercial seafood species along the coast of China. This study investigated how clams from three geographic populations spanning a latitudinal gradient—Liaoning Dandong (north), Jiangsu Rudong (center), and Guangxi Qinzhou (south)—differ in their shell morphology and key physiological functions. We found clear differences in shell shape and in processes such as feeding, metabolism, and burrowing behavior. Clams from the warmer southern region (Guangxi) performed better at a higher temperature (20 °C), showing higher feeding and metabolic rates. In contrast, clams from the cooler northern region (Liaoning) were more active at a lower temperature (18 °C). The Jiangsu population showed intermediate characteristics. These results demonstrate that the clams have developed population-specific adaptations to their local thermal environments. Our findings provide a scientific basis for selecting suitable clams for aquaculture in different regions and for conserving their genetic resources.
Abstract
The clam Meretrix meretrix (Linnaeus, 1758) is a commercially significant bivalve species widely distributed along China’s coast. To investigate the differences among geoducks from different geographic populations, this study investigated the geographical variations in morphology and key physiological traits among three populations spanning a latitudinal gradient: Liaoning Dandong (north), Jiangsu Rudong (center), and Guangxi Qinzhou (south). We analyzed nine morphological traits and measured physiological indicators—including filtration rate, feeding rate, oxygen consumption, ammonia excretion, and burrowing behavior—at two temperatures (18 °C and 20 °C). The results revealed significant morphological differentiation among the populations. Physiologically, the Guangxi population demonstrated superior adaptation to warmer conditions, exhibiting the highest feeding and metabolic rates at 20 °C. In contrast, the Liaoning population performed better at the lower temperature of 18 °C, while the Jiangsu population showed intermediate characteristics. Furthermore, burrowing capacity varied significantly, with the southern population having the highest burrowing rate. These findings demonstrate clear population-specific adaptations to local thermal environments, likely driven by long-term acclimatization. This study provides a crucial scientific basis for the conservation of genetic resources and informs regionalized aquaculture strategies for M. meretrix, emphasizing the importance of selecting locally adapted populations for cultivation.