News Finding: The authors of the dolphin study raised similar concerns.
Paper Finding: The dolphin whistles had a less complex contour shape during increased ambient noise in the 2.5 and 20 kHz TOLs.
News Context: The team suggests that more research would help determine if these sounds increased the stress levels of the affected humpbacks. The authors of the dolphin study raised similar concerns. "These whistles are really important," Bailey said in the statement.
Paper Context: Over the entire deployment period, relatively high ambient noise levels were mainly caused by vessel noise and were above 120 dB re 1 mPa 11% of the time (electronic supplementary material, figures S4 and S5). The dolphin whistles had a less complex contour shape during increased ambient noise in the 2.5 and 20 kHz TOLs. Since these frequencies are outside the mean range of the whistles, this suggests that the signaller responded by modifying the call as opposed to the received call losing components through masking.