EMERGING CONCERNS - Marine Pollution: What Everyone Needs to Know - page 133

impulses of compressed air into the water about once every 10
to 12 seconds. Seismic surveys produce sounds with pressures
higher than those of other man-made sources besides explo-
sives. In seismic airgun testing, a ship tows a seismic airgun
that shoots extremely loud blasts of compressed air through
the ocean and miles under the seafloor to locate oil and gas
deposits. These airguns must be incredibly powerful in order
to penetrate the water and the earth's crust and then bounce
back up to the surface. In fact, this sound is 100,000 times more
intense than a jet engine. Tests would last 24 hours for 33 days
and would kill or injure marine mammals (some of them
endangered species), including whales, dolphins, porpoises,
seals, and otters. This powerful disturbance drives whales,
dolphins, sea turtles, and fish away from feeding or fishing
grounds, disrupts important behaviors like mating or caring
for their young, and could cause permanent hearing loss or
death. A deaf marine mammal cannot survive as they rely
on hearing to communicate, navigate, and find food. There is
no way of knowing if an impact kills an animal outright or
whether it dies later from hearing loss or environment impact.
Seabirds and other species, such as endangered sea turtles,
could be affected as well. Fishermen are concerned about det-
rimental effects on their livelihoods.
What effects are produced by noise pollution?
Noise pollution can cause both lethal and sublethal effects, as
reviewed by Weingart. Most animals are alarmed by the loud
sounds, which may damage internal organs (especially ears),
and cause panic. Normal communication between marine
animals can be disrupted by noise. Scientists are investigat-
ing which frequenc 1ies and at what levels noise negatively
affects marine life. Sea mammals have excellent hearing to
take advantage of sound and to compensate for poor visibil-
ity—the heads of whales and dolphins are full of resonant
chambers that give them extraordinary hearing. Naval sonar