The Ocean. The deep sea. A world where sound and hearing are vital. Many marine animals orientate and communicate acoustically. However, this also means that noise can become a deadly danger.
Imagine: Explosions every 10 seconds, generating sound of more than 230 decibel (dB), for weeks or even months. This noise is emitted by so-called airguns, dragged by exploration ships searching for hydrocarbon resources in the seabed. You may wonder how to imagine 230 dB. In fact, this is hardly possible. First you have to consider that the decibel scale is logarithmic, not linear. This means that 20 dB are not double the sound energy of 10 dB, but tenfold! The human threshold of noise pain is about 130 dB. Now recall that noise travels five times faster in water than in air. And under water, there are no barriers to noise. Thus, marine wildlife cannot find shelter from noise even in protected areas.
Intensive underwater noise is also being caused by active sonar systems used by navies, who use low- and mid-frequency sonar to scan vast ocean regions for submarines. And by pointing to national security, armed forces regularly elude environmental protection regulations. Transparent access to information is hardly ever granted.
In many regions, an ever growing noise level by ship traffic adds to all this.
We know about the consequences
Marine animals get enwrapped in an acoustic veil. Avoiding or fleeing from habitats, temporary and long-term hearing damage, and even death are among the consequences caused by noise. Recent studies show that intensive noise harms not only marine mammals, but the marine habitat as a whole, included increasing mortality among krill. This also means that we have to consider noise when we talk about conserving commercial fish stocks for nutrition security.
SHIFTING VALUES is working with and for the teams of OceanCare and Natural Resources Defense Council (NRDC) to obtain measures against intensive noise sources, focusing on the Mediterranean Sea.