Sounds Travel Farther Underwater As World's Oceans Become More Acidic

ScienceDaily (Sep. 30, 2008) —

It is common knowledge that the world's oceans and atmosphere are warming as humans release more and more carbon dioxide into the Earth's atmosphere. However, fewer people realize that the chemistry of the oceans is also changing—seawater is becoming more acidic as carbon dioxide from the atmosphere dissolves in the oceans.

According to a paper to be published this week by marine chemists at the Monterey Bay Aquarium Research Institute, these changes in ocean temperature and chemistry will have an unexpected side effect—sounds will travel farther underwater.
Conservative projections by the Intergovernmental Panel on Climate Change (IPCC) suggest that the chemistry of seawater could change by 0.3 pH units by 2050 (see below for background information on pH and ocean acidification). In the October 1, 2008 issue of Geophysical Research Letters, Keith Hester and his coauthors calculate that this change in ocean acidity would allow sounds to travel up to 70 percent farther underwater. This will increase the amount of background noise in the oceans and could affect the behavior of marine mammals.
Ocean chemists have known for decades that the absorption of sound in seawater changes with the chemistry of the water itself. As sound moves through seawater, it causes groups of atoms to vibrate, absorbing sounds at specific frequencies. This involves a variety of chemical interactions that are not completely understood. However the overall effect is strongly controlled by the acidity of the seawater. The bottom line is the more acidic the seawater, the less low- and mid-frequency sound it absorbs.
Thus, as the oceans become more acidic, sounds will travel farther underwater. According to Hester's calculations, such a change in chemistry will have the greatest effect on sounds below about 3,000 cycles per second (two and one half octaves above "middle C" on a piano).
This range of sounds includes most of the "low frequency" sounds used by marine mammals in finding food and mates. It also includes many of the underwater sounds generated by industrial and military activity, as well as by boats and ships. Such human-generated underwater noise has increased dramatically over the last 50 years, as human activities in the ocean have increased.
The MBARI researchers say that sound already may be traveling 10 percent farther in the oceans than it did a few hundred years ago. However, they predict that by 2050, under conservative projections of ocean acidification, sounds could travel as much as 70 percent farther in some ocean areas (particularly in the Atlantic Ocean). This could dramatically improve the ability of marine mammals to communicate over long distances. It could also increase the amount of background noise that they have to live with.
There are no long-term records of sound absorption over large ocean areas. However, the researchers cite a study off the coast of California that showed an increase in ocean noise between 1960 and 2000 that was not directly attributable to known factors such as ocean winds or ships.
Hester's research shows once again how human activities are affecting the Earth in far-reaching and unexpected ways. As the researchers put it in their paper, "The waters in the upper ocean are now undergoing an extraordinary transition in their fundamental chemical state at a rate not seen on Earth for millions of years, and the effects are being felt not only in biological impacts but also on basic geophysical properties, including ocean acoustics."
This research was supported by grants from the David and Lucile Packard Foundation.
Ocean acidification: background information
Over the last century, cars, power plants, and a variety of human activities have released hundreds of billions of tons of carbon dioxide (CO2) into the Earth's atmosphere. In analyzing the effects of this planet-wide chemistry experiment, scientists discovered that about half of this CO2 has been absorbed by the world's oceans. In the last five or ten years, chemical oceanographers have come to the conclusion that adding carbon dioxide to the oceans has caused them to be more acidic, just as adding carbon dioxide to water causes the resulting soda water to become more acidic.
Chemists measure acidity using pH units, with a scale that runs from 0 (the most acidic) to 14 (the least acidic, or most basic). Neutral tap water, for example, has a pH of about 7. For comparison, lemon juice has a pH of about 2 and the acid in your car battery might have a pH of 0.8. Seawater, on the other hand, is usually slightly basic, with a pH of about 8.1.
Marine chemists (including MBARI's Peter Brewer) estimate that the pH of the world's oceans has already dropped by about 0.1 pH units since the beginning of the industrial revolution, about 250 years ago. They further estimate that the pH of the ocean may drop by another 0.2 pH units (to 7.9) by the year 2050. This may not seem like much of a change, but it could have significant impacts on corals and other marine organisms whose body chemistry is adapted to millions of years of relatively constant chemical conditions.

Journal reference:
K. C. Hester, E. T. Peltzer, W. J. Kirkwood, and P. G. Brewer. Unanticipated consequences of ocean acidification: A noisier ocean at lower pH. Geophysical Research Letters, Vol. 35, No. 31 (October 1, 2008)
Adapted from materials provided by Monterey Bay Aquarium Research Institute.


Considering that we were talking about carbon dioxide and green house emissions in our oceans, i thought this article was excellent, and it touched on the subject. Ocean acidification is becoming more known which is a good thing.... but it's becoming well known for negative reasons, and that is because it is becoming more common. I think it is important that we try to educate ourselves on this topic and try to understand it as much as possible.

Cuba and the Greater Antilles

For two decades, WWF-Canada has been helping to conserve the coral reefs, mangrove swamps, and other key habitats that support Cuba's exuberant diversity of life.
We have gone from pilot projects to full-scale, regional initiatives that are greening Cuban tourism, promoting sustainable fishing practices, and building a network of marine protected areas. In the process, we have earned the respect of the federal government and local communities alike.
And while our conservation expertise is making an impact in Cuba, Canada has much to learn in return. Cuba is currently the only country on the globe to meet WWF's criteria for sustainable development, minimizing its ecological footprint while preserving a healthy standard of living.


After attending the talk the other day that we had in class i thought this little article was very relevant ! i thought it was wonderful how cuba was trying to improve the sustainability of their country as well as finding more eco freindly ways of doing things, such as the increase of solar panals to power their homes, and compression cookers. i was so excited to see this little article on WWF canada's site. It is nice to know that cubas efforts are not going un noticed, and that hopefully other countries will try to follow in cubas foot steps and try to improve the way they consume and use energy and come up with new innovative ways to decrease their eco foot print!

NAFO Decisions Undermine Cod Recovery: But Progress Made on Protecting Vulnerable Habitats – WWF-Canada

(Toronto: September 26, 2008)
The Northwest Atlantic Fisheries Organization (NAFO) made decisions that will undermine cod recovery during their annual meeting in Vigo Spain this week. The status of cod on the southern Grand Banks remains severely depleted despite 14 years under fishing moratorium. The outcomes from the meeting demonstrated that there still lacks a sense of urgency to halt levels of bycatch that threaten the recovery of this stock.Last year NAFO adopted a southern Grand Banks cod recovery strategy to reduce bycatch of cod by 40 per cent. This year NAFO made decisions that will lead to increases in cod bycatch in 2009 without knowing whether this target was met. Of most concern were decisions to increase the yellowtail flounder catch limit, and maintain the thorny skate limit well above scientific recommendations. These decisions have the potential to directly impact cod in 2009.NAFO did take some important steps towards the protection of vulnerable habitats, such as coldwater coral forests. For example, measures were adopted to limit the impacts of bottom fishing in new fishing areas and provide for the protection of corals when encountered. New measures were also put in place to protect the Fogo Seamounts (undersea mountains located southwest of the Grand Banks). These efforts were strengthened by commitments to conduct new sea floor mapping and research. “The decisions affecting cod bycatch are not consistent with NAFO’s commitments to the precautionary and ecosystem management,” said Dr. Robert Rangeley, Vice President Atlantic, WWF-Canada. “The only hope we can see for this situation is for NAFO and member countries to immediately implement more stringent measures to reduce cod bycatch in their fleets. Continuing with the status quo will surely wipe out the promising 2005 year class and the best opportunity for the recovery of this stock.”The recovery of the southern Grand Banks cod population will depend on the survival and reproduction of pulses of young cod in the population, such as occurred this year. Increases in bycatch in 2009 will jeopardize the survival of these young fish.


--30--For further information: Stacey McCarthyCommunications Specialist WWF-Canada, Atlantic RegionTel: 902.482.1105 x 41Cell: 902.209.6457Email: smccarthy@wwfcanada.org

Robert RangeleyVice President, AtlanticWWF-CanadaTel: 902.482.1105 x 23Cell: 902.401.1569Email: rrangeley@wwfcanada.org

This is an article that i found on WWF canada, which i found was very relevant to some of the topics that we discuss in class. I think that it is really good that the NAFO is trying to take steps closer to protect natural habitats along the grand banks.