National Issue

photo of whale tail
How do you record the ocean soundtrack? With a hydrophone! Postdoctoral researcher Dr. Jenni Stanley has been deploying hydrophones at several national marine sanctuaries in order to characterize their soundscapes. Learn more in our video!

Many marine organisms, including marine mammals, turtles, fish and invertebrates, rely on sound and hearing for their survival. In general, sound can be perceived over greater distances than sight or smell underwater, and sound is the primary way that many marine species gather and understand information from other organisms and their environment in the ocean. NOAA and the Office of National Marine Sanctuaries' approach to managing ocean noise aims to reduce negative physical and behavioral impacts to species, as well as conserve the acoustic quality of their habitats.

Increasing human activity within our oceans over the last 100 years has also meant increasing levels of noise. Sources of underwater noise include merchant shipping traffic such as container ships and tankers, smaller recreational and commercial vessels, sonar and explosions used in military defense operations, pile drivers and dredging used in marine construction, airguns and other seismic sources used in energy exploration, active acoustic sources used in research activities, explosions used for platform removals, and introduction of noise from air and land sources such as roads and overflights. The increasing amount of noise from anthropogenic sources is a rising concern due to its potential to negatively impact marine ecosystems and organisms in several ways.

diagram showing examples of noise in the ocean and instruments that measure noise levels
A mooring containing a hydrophone was deployed in Cordell Bank National Marine Sanctuary in October 2015. Watch this video to see its deployment and to learn more about the importance of monitoring noise in our oceans!

Scientific research suggests that anthropogenic noise can reduce opportunities for animals to hear sounds used for navigation, finding food, finding mates, and avoiding predators. Additionally, increased background noise can impact communication, such as the type of communication between mothers and offspring, or communication used in group dynamics. Noise can also alter behavior and result in lower chances of survival and reproduction for marine organisms. Lastly, noise from acute sound sources can cause physical injury in the form of temporary or permanent hearing loss or tissue damage.

ONMS is working to understand long term changes in noise levels (both anthropogenic and natural noise) within the National Marine Sanctuary System. We are currently developing a program to build a network of noise monitoring stations that collect multiyear, continuous and comparable data to detect changes and establish baselines across the sanctuary system.