Question - What are the activities and sources responsible for increasing the noise in the ocean? Do we have any idea of how much ocean noise has increased in the last few decades?

Answer - Sometimes Global Climate Change can be something which has altered unseen environments over the past hundred years.  The underwater “soundscape” or ambient noise of the oceans has been increasing for decades due to the human presence in the seas.  The ever increasing industrialization of our oceans has introduced underwater sound sources such as military sonars, seismic air guns used for oil and gas exploration, pile driving, shipping, and recreational boating.  Over the past few decades the contribution of commercial shipping in particular to ambient noise has increased by as much as 12dB a significant increase above the natural background noise in some locations. Anthropological noise associated with these activities and industrialization has increased across the underwater sound spectrum, but especially in the low frequency range (< 500Hz) which, in the ocean, can propagate for hundreds of kilometers.

Q - What do we know about noise in the ocean? Why is a noisy ocean a problem? What evidence exists to show this problem?

A - We are just beginning to understand the wide variety of sounds in the ocean and the role of sound in the life and behavior of marine animals. Many marine animals rely on acoustics for sensing their environment and for communication and foraging.  Low frequency sounds are very important for many marine species and this is the range experiencing the most increase by humans. 

Animal responses to changes in background sounds, or even local noise sources can be difficult for scientists to observe.  Animal strandings linked to military sonar exercises are the most easily observed evidence of a behavioral response to sound stress.  In addition, there is suspicion of a similar syndrome of decreased capacity to perform normal life functions in a wide range of marine fauna.  For example, several whale species have been found to “raise their voices” or change their calls in order to communicate or will stop vocalizing all together in the presence of high level background noise. 

Q - How would the quiet ocean experiment address the issue?  Who would participate in the experiment? What are the main objectives? 

A - Our knowledge of the way most marine organisms sense and respond behaviorally to sound stimuli is very limited.  We need to illuminate the types of responses by individual organisms elicited by different noises, likely focusing mostly on keystone, indicator, and species already identified as endangered. The “quiet ocean” idea of the experiment is to compare behavioral changes when background sound levels changes, by either directly manipulating the background noise, or conducting studies in “before and after” mode in locations where the oceanic noise changes, such as before and during marine construction projects or when marine traffic may be re-routed from one area to another. 

The IQOE is coordinated by the Scientific Committee on Oceanic Research (SCOR) and the Partnership for Observation of the Global Oceans (POGO).  The IOC, through the Global Ocean Observing System, is involved to evaluate the possibility of global systematic observations of the ocean “soundscape”.  The IQOE aims to collaboratively engage the global oceanographic community by combining the expertise of physical oceanographers, acousticians, behavioral biologists, ecosystem modelers, and population biologists. 

The objectives are to quantify the ocean soundscape on global scales, determine behavioral change thresholds of various species, and examine the functional relationship between sound and the viability of key marine organisms, at an individual scale, a species scale and the ecosystem level.

Q - What would be the IOC’s role to solve the problem? And what is the aim of the August 30 meeting?

A - The purpose of the meeting is to develop a Science Plan for an International Quiet Ocean Experiment.  This open forum will allow us to identify information gaps and to gather broad community input on the important research, observations, and modeling activities that should be included in the decade-long, international, research experiment.  Ideally the IOC will facilitate international and, if needed, intergovernmental cooperation to address this issue at global scales, and integrate continuous, sustainable acoustic measurements into our understanding of global climate change.