| Underwater noise pollution has emerged as a critical environmental issue affecting fish behavior and ecosystem stability. Current behavioral studies on noise stimulation predominantly focus on behavioral alterations in fish before and after noise exposure, primarily examining ecological aspects such as swimming velocity, activity range, and group dynamics. However, these investigations often lack integrated analysis combining fish auditory sensitivity with noise signal characteristics, thereby limiting comprehensive understanding of the intrinsic mechanisms underlying behavioral responses. Building upon conventional ethological observation, this study employs quantitative significance testing with swimming speed as a behavioral metric to investigate stress-related behavioral characteristics of goldfish (Carassius auratus) under abrupt noise stimulation. We systematically compare behavioral differences elicited by continuous single-frequency noise versus sinusoidal pulse-modulated noise, while further elucidating the operational mechanisms through auditory characteristics, noise properties, and behavioral regulation frameworks. This work provides novel perspectives for understanding behavioral adaptation mechanisms in aquatic organisms under noise-disturbed environments. Innovatively, this research proposes phenotypic behavioral parameters (e.g., swimming velocity) as indirect indicators of fish auditory sensitivity, with experimental validation. Results demonstrate that noise stimulation significantly increased both median swimming speed and velocity variation range compared to control groups. Pulse noise, characterized by intermittency, high instantaneous sound pressure levels, and complex spectral structures, induced stronger stress responses than continuous noise, exhibiting maximum differences of 96.5% in velocity increment ratio and 8.68 cm/s in velocity variation range. At 500 Hz (the frequency of peak auditory sensitivity), both continuous and pulse noise elicited most pronounced behavioral responses, with velocity increments reaching 153.79% and 169.61% respectively. Furthermore, negative correlations were identified between swimming speed variations and auditory thresholds: lower auditory thresholds corresponded to higher median swimming speeds and greater velocity increments. These findings suggest that noise-induced swimming speed alterations could serve as surrogate indicators for conventional audiometric measurements in assessing fish auditory sensitivity. |
