Effects of Ammonia Concentration on Sperm Vitality, Motility Rates, and Morphology in Three Marine Bivalve Species: A Comparative Study of the Noble Scallop , Chinese Pearl Oyster , and Small Rock Oyster .

Ammonium (NH) plays a crucial role in the reproductive processes of key biotic groups in aquatic ecosystems-bivalves. This study aims to elucidate the effects of three different ammonium ion concentrations on sperm vitality, swimming kinematics, and morphology of , , and . The results indicate that the sperm vitality and motility rates of and are inversely proportional to the ammonium concentration, especially in the treatment group with an ammonium concentration of 3 mmol/L, where the decrease in sperm vitality and motility is most significant. In contrast, the sperm of reacted differently to increasing ammonium concentrations. After the addition of 2 mmol/L of ammonium, the sperm vitality and motility of reached a peak, showing a significant stimulatory effect. Additionally, as the ammonium concentration increased, the curling of the sperm flagella in and increased. However, sperm flagella curling in showed no change compared to the control group. This study provides insights into the effects of ammonium concentrations on the sperm vitality and motility of three marine bivalve species and highlights the importance of sperm flagella curling as a factor affecting sperm.