Recognition of specific amino acids in migratory rivers and daily rhythmic behavior of naked carp (Gymnocypris przewalskii)

Abstract

Abstract Gymnocypris przewalskii is an endemic migratory fish in the high-altitude, saline-alkaline Lake Qinghai. This study investigated whether L-serine (Ser) acts as a chemical cue guiding its migration. Water analysis revealed significantly higher concentrations of Ser in migratory rivers than in the lake, where phenylalanine (Phe) dominated. In behavioral experiments, G. przewalskii exhibited a significant preference for Ser-enriched water during the daytime (10:00, 15:00, 18:00), spending 63% to 74% of the time in the Ser chamber, while their preference for Ser diminished at night (21:00), where the time spent in the Ser chamber was only 34%. Additionally, G. przewalskii showed significantly lower instantaneous swimming speeds and reduced turning frequencies in the Ser-enriched water compared to the control group, indicating a more stable behavioral pattern. Furthermore, continuous monitoring revealed that the migration frequency of G. przewalskii during the daytime was significantly higher than at night, suggesting that light conditions may interact with chemical cues to regulate their migratory behavior. This study provides evidence of significant differences in the amino acid composition between the lake water and the migratory rivers of Lake Qinghai, as well as G. przewalskii ’s preference for Ser in the migratory rivers. It also highlights the distinct diel rhythmicity in their migratory behavior, offering valuable scientific insights for understanding the adaptive mechanisms of saline-alkaline fish species. These findings also have important implications for the conservation of the Lake Qinghai ecosystem.