Greenhouse gases make oceans noisier: UN, wildlife groups

Yahoo News 3 Dec 08;

ROME (AFP) – Greenhouse gases worsen ocean noise by raising acidity levels and causing sound to travel farther, making it ever harder for marine mammals to communicate, UN and wildlife experts said Wednesday.

"Acidity is a new, strange and unwanted development... for a whole range of marine animals," Mark Simmonds of the Whale and Dolphin Conservation Society told a news conference.

Simmonds, the society's scientific director, was speaking as the UN Convention on the Conservation of Migratory Species (CMS) began three days of debate on a resolution aimed at combatting ocean noise, which is caused primarily by shipping, oil and gas exploration and military sonars.

"Noisy activities are producing an acoustic fog that prevents whales from maintaining social groups, finding each other for breeding purposes, and so forth," Simmonds said.

The Monterey Bay Aquarium Research Institute in California, which is studying the rising acidity of seawater, says on its website: "As the oceans become more acidic, sounds will travel farther," notably low-frequency sounds "used by marine mammals to find food and mates."

Legal expert Veronica Frank of the International Fund for Animal Welfare said ocean noise has doubled each decade for the past 40 years and is expected to keep increasing.

"Blue whales' capacity to communicate has been reduced by 90 percent," she said.

The proposed resolution would urge the 110 parties to the CMS to mitigate the impact of ocean noise on vulnerable species, assess the environmental impact of sound-producing activities and avoid the use of high-intensity naval sonars that could pose risks for marine mammals.

The issue of ocean noise is an "international hot potato" because of the commercial and military interests involved, Simmonds said.

One study found that sounds from seismic surveys using powerful airguns travelled more than 3,000 kilometers (1,800 miles) from the source, the UN Environment Programme said in a communique.

Sound naturally travels farther in water than air because water has more mass.

Man-Made Noise In World's Seas Threatens Wildlife
Silvia Aloisi, PlanetArk 4 Dec 08;

ROME - Man-made noise in the world's seas and oceans is becoming an increasing threat to whales, dolphins and turtles who use sound to communicate, forage for food and find mates, wildlife experts said on Wednesday.

Rumbling ship engines, seismic surveys by oil and gas companies, and intrusive military sonars are triggering an "acoustic fog and cacophony of sounds" underwater, scaring marine animals and affecting their behavior.

"There is now evidence linking loud underwater noises with some major strandings of marine mammals, especially deep diving beaked whales," Mark Simmonds, Science Director of the Whale and Dolphin Conservation Society, told a news conference in Rome.

Simmonds, who was speaking on the sidelines of a December 1-5 United Nations Environment Program's Convention on Migratory Species conference, said there are also growing indications that certain tissue damage in cetaceans is linked to noise.

Experts suspect that startled animals may tend to dive erratically and suffer something similar to human divers getting the "bends" -- illness symptoms experienced when divers do not carry out proper decompression stops after a long or deep dive.

According to "Ocean Noise: Turn It Down," a new report by the International Fund for Animal Welfare, the distance over which blue whales can communicate has been cut by 90 percent as a result of higher noise levels.

Over the past 50 years, low frequency underwater noise has doubled every 10 years over the previous decade, while the number of ships has tripled, the report also said.

It added that sound produced by air guns used for seismic surveys in oil exploration can travel more than 3,000 km (1,864 miles) from their source.

The rising number of vessels, and their increasing speed, has led to more ships striking marine animals already threatened by hunting and climate change.

Experts say there are also concerns that rising levels of carbon dioxide are pushing water acidity levels up and contributing to noisier oceans, because when acidity rises, water absorbs less noise.

"If there is a lot of background noise, the animals can't hear the boat coming," said Simmonds. "It's the cocktail party effect."

Marine conservationists at the Rome conference are urging governments and industry to adopt quieter ship engines, tighter rules on seismic surveys and less disrupting sonar technologies by navies.

The European Union has submitted a draft resolution to the convention calling on members to consider a wide range of measures to reduce underwater noise.

But Simmonds said conservationists were concerned that pressures from the military and energy industry as well as the need for more research into marine noise pollution may lead to the resolution being substantially weakened.

"We simply don't know at this stage how many animals are affected by noise pollution, but the lack of full scientific evidence should not be a reason to delay action, said Simmonds."