Saving the Ocean
OCR seeks to understand the impacts of human generated noise on marine life – using our understanding to inform ocean policy and practice.
Of concern are the noises generated by underwater acoustical communication networks, military sonar, seismic airgun surveys, seafloor oil and gas processing, and shipping noise These noises can impose various impacts on marine life across al taxa – cetaceans (whales, dolphins, porpoises), pinnipeds (seals and sea lions), fish, and marine invertebrates.
The snap noise of a snapping shrimp can be as loud as a point-blank muzzle crack of a 30 caliber rifle = 220dB (re 1µPa)
Acoustical energy moves through
air at ~ 343m / second;
water at ~ 1560m / second;
ice at ~ 3,900m / second;
oak at ~ 4100m / second;
aluminum at 5240m (17,200’) per second.
Sound travels about 4.3 times faster in water than in air.
Unwanted noise causes species to communicate louder which is known as the Lombard effect.
“Decibels” (dB) are an expression of a measured amount relative to a known amount, like the scale to measure earthquakes.
Many fish grind their “pharyngeal teeth” (in their throats) to make sound which is amplified by the resonance of their air bladder.
Whales and dolphins make sounds by passing air through a twin muscle formation called “monkey lips”.
Seals use their whiskers, called “vibrissae” to sense turbulence in their environment.