The ocean has become a noisy place. Ships, motorboats, offshore construction projects, even aircraft can be heard from the seafloor, and the din can be deafening. Noise pollution is a problem for whales, dolphins and other marine animals that depend on sounds to communicate, hunt, find mates and navigate complex seafloor terrain.
Although underwater sound pollution is suspected to have many negative impacts on marine life, pinning them down is not so easy. To do so, we need to better understand when and why marine animals use different types of vocalizations and how they mentally process the sounds they hear. Next, we require detailed knowledge of short-term and long-term physiological effects from different types of underwater noises. In addition, well-defined measurement protocols are needed, to help researchers take better snapshots of current ambient noise levels and guide the collection of long-term noise level records.
Researchers at Spain’s Technical University of Catalonia Laboratory of Applied Bioacoustics are addressing these challenges by monitoring and analyzing live audio data from hydrophones attached to Ocean Networks Canada’s network and the ESONET network in Europe. After many months of hard work, the live analyses of acoustic recordings from our Barkley Canyon and Folger Passage locations are now available to the public via the Listening to the Deep Ocean (LIDO) website.
This amazing website lets you listen in beneath waters of the northeast Pacific, Mediterranean and North Atlantic. But it does much more than that. Clicking on a station generates a statistical breakdown of detected sounds from toothed and baleen whales, dolphins, ships and other sources. Individual hydrophone listening pages include spectrograms, source probability calculations, detection markers, location maps, noise calculations, signal detection types and server communications streams.
How it works
Acoustic monitoring of cetacean distributions was initiated in the 1970s. The technique was rapidly applied to tracking whales over large distances. Advances in electronics, computers, and numerical analysis now make Passive Acoustic Monitoring (PAM) technology more accessible. To be successful, PAM systems must effectively isolate targeted calls from the rest of the acoustic signal in which they are imbedded or mixed, especially for distant sources and low signal-to-noise ratios. This can be quite challenging, considering the large variations in natural and man-made underwater sounds found in different seasons, regions and marine environments.
The LIDO server downloads uncompressed hydrophone data from Ocean Networks Canada every 5 minutes. The LIDO software then divides the recordings into frequency bands covering the acoustic niches of most marine animal species. Each band is analyzed by a series of sophisticated detection, classification, localization and tracking algorithms. Historical data are also collected, enabling scientists to assess the short-, medium- and long-term contributions and trends of various noise sources in different acoustic settings.
The LIDO contribution to real-time assessment of noise interactions with cetaceans as well as to the long-term management of anthropogenic sound sources represents a major step toward understanding and improving the acoustic environment for marine organisms.