Sinusoidal whistle of captive indo-pacific bottlenose dolphins(Tursiops aduncus) in relation to their behavior and water environment

In order to analyze effects the water environmental elements on behaviors of captive Indo-Pacific bottlenose dolphins (Tursiops aduncus),vocalizations and emotion related behaviors,water temperature,salinity,acidity and alkalinity were observed and recorded throughout one year.The sinusoidal whistles of dolphins produced from 17:00 to 08:00 were selected by time-frequency filtering and analysis.The results which obtained by means of statistics,comparison and correlation analysis were given as follows: (1) the occurrence proportion of sinusoidal whistles was positively correlated with that of dolphins' negative emotional behavior (goodness of fit R² = 93.89%).The dolphins produced most sinusoidal whistles between August and October,at the same time the dolphins had most negative emotional behavior. (2) the occurrence proportion of sinusoidal whistles was related to the mean monthly temperature and salinity of the water environment (goodness of fit R²=68.61%).However,the occurrence proportion of sinusoidal whistles was not affected by the acidity and alkalinity. (3) The occurrence proportion of negative emotional behavior in dolphins could be less than 12% when the mean monthly temperature and salinity of water environment were within a certain range.The results of this study provide some scientific references for estimating biological behaviors and physical condition of dolphins and whether the captive environment for dolphins is comfortable or not using whistle signals in the future.