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Environmental News Service (ENS)

Noisy, Acid Oceans Increasingly Harmful to Whales


The largest animals on Earth, blue whales are vulnerable to noise and ship strikes. This blue whale died in September 2007 in the waters off Santa Barbara, California. (Photo courtesy Santa Barbara Museum of Natural History)

ROME, Italy - Oceans and seas are
becoming noisier with more vessels, increased seismic surveys for oil
and gas, off-shore construction and recreation, and a new generation of
military sonars, an alliance of wildlife groups said today. They warn
that the cacophony is intensifying threats to marine mammals that use
sound to communicate, forage for food and find mates.

The groups, attending the United Nations Environment
Programme's Convention on Migratory Species conference in Rome, are
urging governments and industry to adopt quieter engines for ships,
tighter rules on the use of seismic surveys, and new, less intrusive
sonar technologies by navies.

At the conference, the International Fund for Animal Welfare
issued a report, "Ocean Noise: Turn it Down," showing that the distance
over which blue whales can communicate is down by 90 percent as a
result of intensified noise levels.

Ship noise in the Pacific Ocean has doubled every decade over the past
40 years and the global shipping fleet is expected to double in size by
2025, after doubling between 1965 and 2003, the report calculates.

Airguns used in seismic surveys generate "colossal" sounds
peaking at up to 259 decibels and can be repeated every 10 seconds for
months. These sounds travelled more than 3,000 km from the source.
There are 90 seismic survey ships in the world, the report states, and
a quarter of them are in use on any given day.

In addition, there are an estimated 300 naval sonar systems
worldwide able to generate pressure sound waves of more than 235
decibels. Pings this loud are over one billion times more intense than
the 145 decibel upper limit deemed safe for humans.

Veronica Frank, an attorney with the wildlife group, said, "We
are calling for wide-ranging action, including a requirement that
builders and owners of all vessels, from super-tankers down, working
with the competent international body, factor noise reduction measures
into vessels' design and operation at the outset."

The news of noisier oceans is emerging alongside new concerns that
rising levels of the greenhouse gas carbon dioxide may be aggravating
underwater noise levels.

Researchers at the Monterey Bay Aquarium Research Institute in
the United States published a study in October showing that rising
ocean acidity can make the marine environment noisier.

Conservative projections by the Intergovernmental
Panel on Climate Change suggest that by 2050 the chemistry of seawater
could increase in acidity by 0.3 pH units.

In the October 1, 2008 issue of "Geophysical Research Letters,"
Monterey Bay's Keith Hester and his co-authors calculate that by 2050
this change in ocean acidity would allow sounds to travel up to 70
percent farther underwater.

The more acidic the seawater, the less low-frequency and mid-frequency
sound it absorbs, said Hester and his team. The changing chemistry of
seawater may mean that currently it is 10 percent less absorbent of low
frequency sound than it was prior to the Industrial Revolution.

Unless greenhouse gases emissions are cut - the key issue this
week in Poznan, Poland at the annual UN climate conference - the rising
ocean acid level will increase the amount of background noise in the
oceans and could affect the behavior of marine mammals, said Hester.

Mark Simmonds, science director of the Whale and Dolphin
Conservation Society, who is attending the Convention on Migratory
Species meeting in Rome, said, "Underwater, man-made noise, is already
triggering a kind of acoustic fog and a cacophony of sound in many
parts of the world seas and oceans."

There is now evidence linking loud underwater noises with some
major strandings of marine mammals, especially deep diving beaked
whales, Simmonds said.

When cetaceans are startled by loud noise, they exhibit unusual diving
behavior and suffer something similar to a human diver getting the
bends, he said.

"Now we are confronted with cutting-edge evidence that fossil fuel
burning and the buildup of C02 may pose a new and even louder threat
unless urgent action is taken to cut emissions over the coming years
and decades," said Simmonds. "There clearly needs to be a comprehensive
and joined-up response to noise pollution in the underwater world."

Robert Hepworth, executive secretary of the UNEP-Convention on
Migratory Species, said climate change is set to make parts of the
ocean that were once relatively tranquil and inaccessible, much

"The retreat of the ice in the Arctic is leading to a scramble
for drilling and oil and gas exploration which is likely to increase
underwater noise exposure for species such as the beluga whale and the
bowhead whale," warned Hepworth. "This increase does not include the
rise in noise as passages around the Arctic open up to ship traffic."

The European Union and its 27 member states submitted a draft
resolution to the governments attending the Convention on Migratory
Species this week, which urges consideration of a wide range of
measures to quiet underwater noise.

Suggestions include noise protection areas in enclosed seas and
sea basins, greater monitoring of noise levels, noise databases that
list where man-made sounds originate, and a set of guidelines on better
managing noise sources.

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