進行聽力與噪音暴露實驗對圈養海豚行為之影響

Abstract

為了瞭解噪音對鯨豚的行為影響，本研究包括兩部分：Ｉ.探討以聽覺誘發電位進行聽力測驗(Auditory evoked potential hearing measurements)對圈養瑞氏海豚(Grampus griseus)日常行為之影響（第二章）, 以及II. 播放低頻噪音暴露實驗對圈養瓶鼻海豚(Tursiops truncates)的行為影響（第三章）。第一部分是於2014 年7-8 月在花蓮遠雄海洋公園就一隻瑞氏海豚進行聽力測驗，每次測試30至40 分鐘，測驗前後5 分鐘以連續紀錄其9 項行為表現與呼吸次數，並比較瑞氏海豚在進行聽力測驗前與後的行為改變。結果發現在聽力測試前後只有「共游」這項行為有顯著差異，且行為多樣性減少。因此我認為進行聽力測驗並不會使此瑞氏海豚有太顯著性的影響。但因被調出水池測試而與同伴頻繁分離，似乎會造成社交行為頻率降低。第二部分是在同地點於2015 年5-7 月對兩隻圈養的瓶鼻海豚進行噪音暴露實驗並評估實驗中的行為表現，實驗噪音為800 Hz 低窄頻聲音，音量分為未放音（擴音器依然放置於水中）、小音量（received SPL at 1m = 133 dB re 1 μPa）及大音量（received SPL at 1m = 153 dB re 1 μPa）等三組，每次進行30 分鐘並錄影記錄，各音量重複5 次，每次實驗擷取最前與最後5 分鐘進行統計分析。結果顯示在不同音量間之比較，海豚在「檢視擴音器」的行為上有顯著差異且多發生在實驗剛開始的5 分鐘，且多發生在大音量組。此外，7 號海豚在大音量時的呼吸速率明顯高於未放音時。本研究顯示當噪音的音量133 或153 dB 的範圍時噪音暴露實驗對兩隻瓶鼻海豚的行為影響沒有顯著性的影響，僅於最初5 分鐘內可能因好奇增加「檢視擴音器」的行為的頻率，雖然在大音量下其他研究發現海豚有急性但輕微的緊迫生理反應。

Dolphins rely on sound for communication, navigation, and foraging, their sense of hearing is one of their most important senses. The hearing sensitivities of many species of cetacean have been determined through experimental studies with captive dolphins. In order to explore the potential impact of anthropogenic sounds on cetaceans, there are two major parts of this thesis: I. evaluating the auditory evoked potential (AEP) hearing measurements hearing test impacts on the behavior of 1 captive Risso’s dolphin (chapter 2); II. investigating the anthropogenic sound exposure experiments on the behavior of bottlenose dolphins in captivity in Taiwan (chapter 3). The first part evaluated the hearing test impacts on 1 captive Risso’s dolphin (Grampus griseus) at Far Glory ocean park at Hualien, Taiwan, from July 2014 to August 2014. The behavioral observations were collected by continuous and focal recording sampling method. 19 observations before the auditory evoked potential (AEP) hearing tests and after the AEP test, each session lasting 5 minutes with 9 behavioral types and breath rate recorded. Comparing the difference between the “Before” and “After” sessions, only the “Gathering” showed significant difference in the behaviors of Dolphin No.17. I conclude that the impact of hearing test on the Risso’s dolphin was not strong but reduced the social behavior in “Gathering” due to the frequently separated with companion. The second part, I introduced a speaker with either no, or sounds of 800 Hz pure-tone sound (133 dB and 153 dB) with 40 strikes/min and duration 0.05 s, were used in sound exposure experiment for 30 min to three bottlenose dolphins in the same pool with only two dolphins were observed to collect behavior data. During each observation session, continuous and focal recording sampling method was applied to record the same dolphin’s behaviors for the first and last 5-minutes periods of each sound exposure session. Each sound level experiments was conducted for five times in random sequence. Result of responses toward 3 sound exposure level shows there were significant difference on “Examing” behavior. The “Examing” behavior of dolphin No.5 and No.7 in “High SPL” sound level also showed significant difference. In addition, “Breath” behavior in “High SPL” of dolphin No.7 was significant higher than “Control” sound level. This study demonstrated there were no significant impact on the 2 bottlenose dolphins when the exposure sound was 133 dB or 153 dB. In the “High SPL” sound level, only “Examing” behavior of two dolphin in first 5-minutes periods of “High SPL” sound level increased significantly which may because of curiosity although there was another study revealed dolphins had short-term and minor stress physiological response.