Monitoring spatial and temporal soundscape features within ecologically significant U.S. National Marine Sanctuaries

Area of Science:

• Marine ecology
• Bioacoustics
• Conservation science

Background:

• The U.S. National Marine Sanctuaries system protects diverse marine environments.
• Coordinated monitoring is challenging due to variability among sanctuaries.
• Underwater sound monitoring offers a versatile tool for marine protected area management.

Purpose of the Study:

• To assess ambient underwater soundscapes across eight sites in four U.S. National Marine Sanctuaries.
• To investigate temporal changes in sound pressure levels and identify species presence.
• To compare soundscape attributes among sites and inform management strategies.

Main Methods:

• Utilized passive acoustic monitoring with standardized equipment and analysis.
• Collected ambient underwater sound data (10-24,000 Hz).
• Derived measurements of sound pressure levels, power spectral density, and identified biotic/anthropogenic signals.

Main Results:

• Broadband sound pressure levels varied significantly (up to 24 dB re 1 µPa) across sites, sanctuaries, and seasons.
• Biotic signals (e.g., snapping shrimp, fish vocalizations) showed diel and seasonal patterns.
• Anthropogenic signals, primarily vessel traffic, varied greatly (1.6-21.8 h/d).

Conclusions:

• Baseline soundscape attributes can be effectively summarized using specific acoustic measurements.
• Passive acoustics provide valuable data for understanding habitat associations and species use.
• Integrating acoustic and non-acoustic data can enhance area-specific management in marine protected areas.