Apparent source levels and active communication space of whistles of free-ranging Indo-Pacific humpback dolphins ( Sousa chinensis ) in the Pearl River Estuary and Beibu Gulf, China

作者：Zhitao Wang, Whitlow W. L. Au, Luke Rendell, Kexiong Wang, Haiping Wu, Yuping Wu, Jianchang Liu, Guo-Qin Duan, Han-Jiang Cao, Ding Wang · 发表于：PeerJ · 年份：2016 · DOI：10.7717/peerj.1695 · 被引用次数：23 · 研究领域：Marine animal studies overview、Animal Vocal Communication and Behavior、Underwater Acoustics Research

Background. Knowledge of species-specific vocalization characteristics and their associated active communication space, the effective range over which a communication signal can be detected by a conspecific, is critical for understanding the impacts of underwater acoustic pollution, as well as other threats. Methods. We used a two-dimensional cross-shaped hydrophone array system to record the whistles of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in shallow-water environments of the Pearl River Estuary (PRE) and Beibu Gulf (BG), China. Using hyperbolic position fixing, which exploits time differences of arrival of a signal between pairs of hydrophone receivers, we obtained source location estimates for whistles with good signal-to-noise ratio (SNR ≥10 dB) and not polluted by other sounds and back-calculated their apparent source levels (ASL). Combining with the masking levels (including simultaneous noise levels, masking tonal threshold, and the Sousa auditory threshold) and the custom made site-specific sound propagation models, we further estimated their active communication space (ACS). Results. Humpback dolphins produced whistles with average root-mean-square ASL of 138.5 ± 6.8 (mean ± standard deviation) and 137.2 ± 7.0 dB re 1 µPa in PRE (N = 33) and BG (N = 209), respectively. We found statistically significant differences in ASLs among different whistle contour types. The mean and maximum ACS of whistles were estimated to be 14.7 ± 2.6 (median ± qua...