Dolphins adjust species-specific frequency parameters to compensate for increasing background noise

Area of Science:

• Marine Biology
• Bioacoustics
• Animal Communication

Background:

• Rising ocean noise levels pose a threat to marine mammal acoustic communication.
• Dolphin whistles are crucial for their social interactions and survival.

Purpose of the Study:

• To investigate the impact of anthropogenic and natural ocean noise on dolphin whistle acoustic properties.
• To analyze how noise affects frequency parameters and variability in dolphin communication signals.

Main Methods:

• Recorded whistles and background noise from short-beaked common, Atlantic spotted, and striped dolphins in the Canary Islands.
• Utilized a towed array with four elements for data collection.
• Measured four whistle frequency parameters and background Sound Pressure Levels (SPL) across seven one-third octave bands (5-20 kHz).

Main Results:

• Dolphins exhibited reduced variability in whistle frequency parameters when exposed to anthropogenic noise.
• Increased end frequencies in whistles were observed in response to rising natural noise levels.
• The study provides the first evidence of SPL synergy influencing whistle structure across three dolphin species.

Conclusions:

• Dolphin whistle structure is adaptively shaped by both natural and anthropogenic ocean noise.
• These findings highlight the complex interplay between noise and marine mammal acoustic behavior.
• Understanding these adaptations is crucial for marine conservation efforts in noisy environments.