Thursday, February 27, 2014

The Precious Pearl

When most people think of a pearl, they think of a piece of jewelry, whether it is a bracelet, necklace, or a pair of earrings. Pearls are one of nature's best gifts to mankind and woman feel proud to wear them and show them off. But what people don’t think about is where these beautiful pearls come from and the other potential benefits they contain.

Pinctada is a genus of saltwater clams of marine bivalve molluscs, also known as the pearl oysters. These oysters have a strong inner shell layer composed of nacre, also known as "mother of pearl," which is an organic-inorganic composite material; it is what makes up the outer coating of pearls. It is strong, resilient, and iridescent. Although it may be thought that all oysters produce pearls, this is not quite the case. Pearl oysters are not closely related to either the edible oysters of the family Ostreidae, or the freshwater pearl mussels of the families Unionidae and Margaritiferidae. The various species of Pinctada produce different sizes and colors of pearls, depending on the size of the species of the oyster as well as the natural color of the nacre inside the shell.

A natural pearl begins its life inside an oyster's shell when an intruder, such as a grain of sand or bit of floating food, slips in between one of the two shells of the oyster. In order to protect itself from irritation, the oyster will cover the invader with layers of nacre and will continue to do so, layer upon layer. Over time, the irritant will be completely encased by the silky crystalline coatings. As a result, we are able to have the lovely gem called a pearl. Check out the video below for a better look at nacre and how it works:

How something so wondrous emerges from an oyster's way of protecting itself is such an amazing ability of nature. In addition to natural pearls, cultured pearls share the same properties. Oysters form cultured pearls in a similar way, the only difference being that a person carefully implants the irritant in the oyster, rather than leaving it to chance.

Besides being a gorgeous piece of jewelry, though, pearls have been found to contain traces of several metals and minerals which are known to have major health benefits! Pearls rich in essential minerals can help treat killer diseases like cancer. Pearls have been used for their medicinal value since their earliest discovery by man. Even today, the pharmaceutical industry continues to use pearls in medicine. Pearls that are of inferior quality and cannot be used in jewelry are those that are ground into a fine powder and used to prepare high-quality pharmaceutical calcium.

Studies have also been performed on pearls to better understand where their benefits come from. In a series of experiments by Ajai Sonkar (a scientist at the Pearl Aquaculture Research Foundation), pearls produced through special culture techniques were  found to contain traces of metal and minerals such as zinc, copper, magnesium, iron, calcium, sodium and potassium. He stated that “these micro-nutrients are essential for various body functions such as metabolism, growth and immunity. Of them, zinc has been found to be playing a major role in preventing fatal diseases like cancer.”

There have actually been numerous other studies performed with similar results, such as one published recently in the British Journal of Cancer which established zinc's anti-tumor role that prevents the growth of cancer cells. Other studies have found that zinc deficiency in the body causes delayed healing of wounds. Presently, Sonkar wants to carry out a comprehensive clinical test to find out health benefits of specially cultured pearls.

In conclusion, that pair of pearl earrings you’re wearing isn’t just your average piece of jewelry. It was created by a marine organism and contains numerous benefits besides being a sight to look at.  It’s amazing to think that in almost every culture, pearls could simply be worn as jewelry, or they could be ground up and made into potions and balms used to treat a wide variety of ailments and conditions. One legend said that a pearl placed in the navel could cure stomach disorders! The possibilities pearls posses are astounding and should definitely be noted.

Radiation: The Next Round!

The aftermath of the Japanese 2011 Tōhoku earthquake and tsunami still makes the news today. The Japanese Fukushima Daiichi nuclear power plant suffered a melt down after the disasters on the March 11, 2011. Environmental and public health concerns, and even government and corruption controversies surround the whole incident. All of which have validity. For the sake of science, this post will only focus on the most recent developments from the disaster that are affecting North Americans. 

Recently this moth, Canadian and U.S. scientists have detected radio active isotopes, cesium-134 and cesium-137, on the coast of Vancouver, British Columbia. The radioactive material has yet to reach the west coast of the U.S. according to Woods Hole ocean scientists. Isotopes are atoms of the same element that have different numbers of neutrons in their nuclei. For example cesium-134 has less neutrons than cesium-137. Cesium-137 has a half-life of 30 years and remains in the environment for several decades. The problem, at least right now, is cesium-134. It only has a half life of two years, but it is more toxic and can cause more problems than cesium 137. 

What makes cesium-134 bad? Currently, any detectable isotopes can be traced back to Fukushima. Surprisingly, cesium-137 has already been present in the atmosphere for decades. Besides Fukushima, sources of cesium-137 can be traced back to nuclear weapons testing overseas and all the way back to the Manhattan project. 

Scientists have been on the look out for radiation along the west coast since the wake of the disaster. All of the cesium-134 was concentrated in the upper 100m of the ocean according to the most recent tests. The results from the February 2014 sampling will be ready soon.  

Despite how scary this all sounds, it is still to early to tell how this will affect certain things. Also, the levels scientists are detecting are very minimal and are not high enough to cause any harm. The infamous Chernobyl disaster released 1000s of times more radiation than what is currently being detected. Currently, scientists are monitoring the Fukushima radiation closely and diligently. Just like the Bluewater Horizon disaster, the management of the Fukushima disaster is a giant science experiment because nothing like this has ever happened before. 

Fukushima's radiation reached coastal Canada first due to the Kuroshio Current. This is a powerful current that flows from Japan across the Pacific. In time, the current and the radiation it is carrying will flow downy he coast of North American and circle back toward Hawaii. This is however, only predictions based of models of the current. To this day, radioactive materials are still leaking into the water and are being carried across the ocean to North America. 

Article Source:

Wednesday, February 26, 2014

Sharks: A Deadly Misunderstanding

Zak Palmer
Image from Woodridge, IL, USA --- Great White Shark Opening Mouth --- Image by © Denis Scott/Corbis

Every year people flock to beaches to get away from humdrum inland life and experience the tropical glory of the ocean. Most people are conscious of the creatures that inhabit these oceans, but in the case of the most sharks, it is for all the wrong reasons. People fear these magnificent creatures and do not understand the importance of their role in maintaining a healthy ocean. You can count the number of people that died from shark attacks last year on two hands. This hardly seems like something to be seriously concerned about as vastly more people die for much less feared reasons on a weekly basis.

Great white sharks are apex predators in the oceans. This means that they are the top predator responsible for controlling a variety of populations which, in turn, control other populations. If an apex predator is lost, then the entire ecosystem is thrown off. Populations that should be controlled grow wild and vastly decrease the numbers of the ones in which they feed. This causes the original population to die off as they run out of food. Health of the great white is vastly important as it has recently been discovered that they can live over 70 years which means they need longer to fully mature. The health of many oceans depends upon the great white.

The situation for the sharks is dire. Humans kill over 100 million sharks each year. Things such as bycatch, purposeful hunting, and accidents. These sharks that are purposefully killed almost never do anything to provoke their killers. It is estimated that over 90% of the predatory fish in the ocean have been eliminated by humans in the last 50-100 years. This number is alarming and contributes to unbalanced ecosystem and aids in the human destruction of oceans.

If the current trend continues, many shark species will be headed towards endangerment or extinction if they are not already there. Sharks currently represent the most threatened marine creatures on the World Conservation Union's red list. It is never a good thing when any species is lost, but it is especially detrimental when the species is of such vast importance.

All hope is not lost however. There are many things that can be done to save millions of sharks. Simple modifications to fishing gear or fishing techniques can save a huge amount of sharks lost from the fishing industry. A general knowledge of the creatures can lead to less deaths due to spiteful killings. A little extra attention when navigating the oceans can help to prevent accidents. As fascinating as sharks are it would be a shame to lose some of them for good. As humans, we need to stop trying to be the apex predators of the oceans and allow the creatures that were meant to be do their jobs. 


Sunday, February 23, 2014

Seahorses: On the Decline

Pair of pygmy seahorses.

Every year, more than 150 million seahorses are collected in the wild and dried for use as souvenirs or medicines.  The wild populations of seahorses are becoming depleted, and many species face the threat of extinction.  According to the most comprehensive inventory of the global conservation status of plants and animals, the International Union for the Conservation of Nature’s Red List (IUCN), 38 species of seahorses are on the list: one as Endangered, seven as Vulnerable, one as Least Concern, and 29 as Data Deficient.  The seahorse population has declined by 20% over the last 10 years (or three generations).    
            There are three major reasons for the decline in seahorse populations: the Traditional Medicine trade, the curio trade, and the pet trade.

Thousands of dried seahorses.
            Hundreds of thousands of captured wild seahorses are used in the Curio trade.  Seahorses are sold as key chains, earrings, paperweights, and novelties in shops for the tourist trade.  Many people don’t realize that they are buying dried animals that were once living in the wild.  
            Approximately 95% of the wild seahorses that are collected are used in Traditional Medicine, especially in Asia and Asian communities.  Seahorses are sold whole and dried or ground for use in tonics and prescription medications.  Seahorses are used to treat asthma, respiratory disorders, sexual dysfunctions, broken bones, and heart ailments.  
Seahorses also fall victim to aquarium hobbyists in the pet trade.  Up to one million seahorses are collected for the aquarium trade every year.  The process of catching the seahorse, packaging it, shipping it, and selling it can take weeks.  By the time the seahorse arrives to a home aquarium, the animal is starved and stressed, which usually results in its demise.         
            Seahorses need to be preserved for ecological, biological, economic, and medical reasons.  Seahorses are important predators, and removing them may disrupt ecosystems.  Their reproductive ecology is important and provides us with a unique opportunity to expand our understanding of reproductive biology: only the male becomes pregnant and most pairs are monogamous.  Seahorses also provide some fisheries with a substantial amount of income in addition to being used to treat a wide range of medical conditions and ailments. 
Project Seahorse, an organization led by biologist Dr. Amanda Vincent, works worldwide to monitor trades, establish protected marine areas, and continue research on seahorses to determine what conservation measures are needed to protect seahorses.
Seahorses are a flagship species for a variety of marine conservation issues.  Seahorses are charismatic symbols of the sea grasses, mangroves, coral reefs, and estuaries.  Protecting seahorses means protecting all of the diverse habitats within our oceans and saving our seas.   


Clownfish: Twisted and Confused

"Clownfish and Anemone"

One of America’s most famous and adored marine fish, the Clownfish, may be even goofier than their name suggests.  These cute orange and white fish that we have grown to love, thanks to the Disney movie “Finding Nemo”, actually live a very twisted sexual life.  You see, the clownfish is hermaphroditic, meaning that they can play the role of both male and female fish.  Although this seems very strange to us humans, it is actually a fairly common practice in the aquatic world. There are said to be as many as 21 families of fish that behave in this kinky manner (Stephens). I don’t know about you but that makes me think twice about the cleanliness of the ocean we swim in.

The clownfish specifically is known as a protandrous sequential hermaphrodite, not to be confused with the protogynous sequential hermaphrodites.  To break this down, sequential hermaphrodites are those which “develop as one gender before changing to the other gender” later in life (Cooney).  Of the sequential hermaphrodites there are the two types.  The protandrous start out as males and can later switch to females, while the protogynous develop as females first and then switch to males.  So let’s tie this all together in terms of the clownfish. 

Imagine you are a clownfish that just hatched from its egg.  You start off life as an undifferentiated male with just your mom and dad around.  Sadly, something happens to the mother and she’s gone which just leaves you and your dad living in this small hypothetical population.  In the name of procreation your dad changes into a female to allow for spawning.  As if it isn’t weird enough, you now must breed with your female father to start a new generation.  This happens and a new generation of undifferentiated males is hatched.  Tragically, after the spawning season is over a shark swam in and ate the father! Being the oldest male you take a long look around and find that there aren’t any clownfish ladies swimming around and thus it becomes your turn to become a female.  This is the reproductive behaviors of the clown fish and in general for any sequential hermaphrodite (Cooney). 
Image from Cooney

Although this seems very strange to us humans who don’t naturally change genders, it is both commonplace and beneficial for these fish.   For a small clownfish, it is a truly a “fish-eat-fish” ocean out there.  Living this type of hermaphroditic lifestyle ensures that there are always both male and females around to safeguard the population density.  

If you are still baffled by how these fish reproduce (don't worry its so foreign to us that it is not an easy concept to grasp) then check out the short video below. It does a great job at displaying how the clownfish changes sex and reproduce. 

BeckmanInstitute. “Sex-Changing Clownfish.” Online video clip. YouTube. YouTube, 27 September 2012. Web. 23 February 2014.

Chow, Samuel. Clownfish and Anemone. 7 October 2010. Ask Nature. Web. 23 February 2014.

Cooney, Patrick. “Finding Nemo Lied…” The Fisheries Blog.” The Fisheries Web. 18 February 2014.

Stephens, Christina. “List of Hermaphrodite Animals.” Animals. Demand Media. Web. 18 February 2014.

Wednesday, February 19, 2014

The Mantis Shrimp

photo from

Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Subclass: Hoplocarida
Order: Stomatopoda

The Mantis Shrimp- very beautiful to look at, but a complete terror in the marine world.

The Mantis Shrimp can be found in shallow waters off the shores of Palos Verdes and Catalina Island in southern California (Cabrillo Marine Aquarium). They are carnivores, and a deadly predator to other marine animals; they hunt for prey by means of stalking and sneak attacks as well as burrowing and waiting motionless for their prey before they snatch them. The Mantis Shrimp's diet includes small crustaceans, snails, clams, and fish.

Mantis Shrimp are not shrimp at all- they're crustaceans. They get their name only because they look like both a praying mantis and a shrimp. Their average size is about 12 inches in length. Reproduction varies among Mantis Shrimp. Some are monogamous, but most are polygamous. All Mantis Shrimp reproduce by sexual reproduction. This is initiated when a male Mantis Shrimp does a courtship fane to let a female know his intentions. ( When they come together, the male will transfer sperm to the female. The female can then choose to retain the fertilized eggs, immediately lay the eggs in her burrow, or keep them on her forelimbs.

There are two characteristics of the Mantis Shrimp that I really want to get down to, though- their eyes and eyesight, and their incredible strength behind their punch and attacks.

First their eyes and sight. As you may know, humans have three types of color receptive "cones". These cones are green, blue, and red; the red cone allows us to see red and colors derived from red- like orange when yellow is added to red, or purple when blue is added to red. (The Oatmeal) Knowing this, imagine having TWELVE to TWENTY-ONE photoreceptors! ALL OF THE COLORS! According to an article by Sebastiaan Mathôt, he says that the upper and lower parts of the eye are like the typical compound eye, but it's the Mantis Shrimp's midband that gives the crustacean their incredible ability to see so many colors. However, even though Mantis Shrimp have the ability to see many different colors, they are TERRIBLE at distinguishing color differences. In the article written by Mathôt, he goes on to explain that scientists have done color discrimination tests on Mantis Shrimp to test their vision. This included using two optical cables in an aquarium that produced color; the crustaceans were trained so that they picked the cable with the specific color (and then they were rewarded with food!). The experiment showed that when the colors were very different, their task proved easy; when they were very close in color, the task proved hard. So it was concluded that Mantis Shrimp can only differentiate between colors that are about 12nm apart... humans can distinguish color differences as small as 1nm. (Awkward...) What a wasted talent! ...Maybe they're just overwhelmed with how many colors they can see. In all seriousness, there are many possible reasons for this, so I would definitely check out Mathôt's article, here, to read more on why the Mantis Shrimp have such trouble using their crazy color sight ability.

photo from UCMP Berkeley

Now onto their terrifying boxing gloves of appendages they have. You should ALWAYS take these little dudes seriously. Mantis Shrimp have what's called raptorial appendages on the front of their bodies; you can think of these like arms, if that helps. They can move these appendages extremely fast- two milliseconds, to be exact. (UCMP Berkeley) To put that into perspective, a blink is 100 milliseconds... but I wouldn't suggest blinking if you know one of these guys is stalking you. The other part of this appendage is what they call a "smasher", and they're freakishly powerful. (HULK SMASH!) Mantis Shrimp use this club-like part of their appendage to completely annihilate any animal with a hard shell. In fact, they can smash so hard, hard shells snap like butter being split by a knife. (Scared yet?) Get this: if their smasher was the size of a human fist, the force of its punch would be equivalent to a twenty-two caliber rifle (UCMP Berkeley); so, in other words... you're dead. If that's not a good comparison for you: a Mantis Shrimp can strike prey with 1,500 Newtons of force; if humans could throw at only ONE-TENTH that speed, we would be able to throw a baseball into orbit! (The Oatmeal)

There's more about their color vision and power punch in a great comic strip on The Oatmeal website. Check it out here:

Sure, the Mantis Shrimp may be beautiful, but these guys are insane. Have fun trying to sleep tonight.

I'm kidding. I will, though, leave you with this video from "True Facts". I would definitely watch this if you want to see their power punch in action (plus, the video is pretty funny).

Tuesday, February 18, 2014

Invasive Sea Anemones Threaten the Health of Coral Reefs Due to Sunken Ships

Healthy coral reef- Picture by Kydd Pollock
Iron leached out from sunken ship with surrounding invasive sea anemone- Picture by Jim Maragos, USFWS 
In 2008, scientists began to notice the declining health of the Palmyra Atoll coral reef in the central Pacific due to several shipwrecks in the surrounding area.  Warming seas and ocean acidification were already affecting the health of the reef, but excessive growth of Rhodactis howesii due to leached iron from sunken ships further reduced the quality of the coral reef.  Iron is an essential element for many marine organisms, but in excess, invasive species like R. howesii can thrive.

R. howesii is a type of sea anemone that is very aggressive.  When excess nutrients like iron are available with no predators to keep populations in check, the anemones thrive.  R. howesii also preys upon coral, which further degrades the health of the coral reef. 

In September 2007, USGS researcher Dr. Thierry Work, Dr. Greta Aeby from the Hawaii Institute of Marine Biology, and Dr. James Maragos from U.S. Fish and Wildlife Service studied a shipwreck from 1991 on Palmyra Atoll in the Pacific Ocean.  The researchers discovered that R. howesii was growing in high densities surrounding the ship, and densities steadily decreased with distance from the wreck.  Since the atoll is isolated, runoff from agricultural or industrial activities is unlikely, so the shipwrecks are the only logical source of excess nutrients. 

With the sea anemone growing rapidly, it causes a change in the dominant life form of the reef and is referred to as ‘phase shift’.  Even though phase shifts can have long-term negative effects, eliminating organisms like R. howesii are an impossible feat, especially over a large area.  Rapid removal of shipwrecks to prevent reefs from being overgrown by invasive species like R. howesii is crucial to reef health. 

Remediation projects are currently being implemented to evaluate the resiliency of coral reefs after shipwrecks removal. On January 29th 2014, the Fish and Wildlife Service completed a $5.5 million conservation project to remove three wrecked ships, weighing a total of one million pounds, from protected wildlife areas in the Pacific Remote Islands National Wildlife Refuge. The shipwrecks caused miles of damage to the Palmyra Atoll and Kingman Reef.  With the reefs being home to 176 species of coral and 418 types of reef fish, protecting the damaged reef from further destruction was vital.  A team of 16 people cut and removed the wreckage from the coral reefs without causing further damage, bringing the salvage to California to be recycled. 

A representative of the remediation project stated, "We know Palmyra Atoll is resilient; it's one of the last remaining healthy coral reefs.  We've done some experiments with removal, and within three weeks we saw new species coming back to the area—mainly microscopic coral recruits.  These resilient areas can heal themselves when they get back on track."

Using Palmyra Atoll and Kingman Reef as controls, scientists can begin to understand how coral reefs heal.  It is possible that these examples can teach scientists in other parts of the world how to restore coral reef health.

Sunday, February 16, 2014

Mapping by satellite pinpoints danger zones for turtles

photograph by Michael Patrick O'neill/Alamy

Many  migratory species in the ocean face a constant battle with fisherman.  However, satellite and fisheries data can help prevent some of these battles.  Some of the animals that are most affected by bycatch include seabirds, turtles, dolphins and cetaceans.  Recently, fisheries and satellites have been tracking leatherback turtles (Dermochelys coriacea) in the Atlantic Ocean and trying to prevent these unintended captures. 

The Atlantic Ocean is home to the last large populations of leatherback turtles.  Because these turtles have a migratory nature and are considered to be the world’s largest turtle, they are very vulnerable to unintended capture by fisherman.  In the past, understanding how to protect these turtles has been difficult because much of the bycatch is not reported by fisherman and the turtles cover very wide paths in the Atlantic.  The satellites have tracked leatherback turtles from 1995 to 2010 to find out many of the zones that the turtles regularly occupy, and to identify some areas where they may clash with fisherman.

A conservation scientist named Brendan Godley explained that the largest obstacle to protecting the turtles has been knowing where, when, and in what fisheries the bycatch is taking place.   He has published research that pinpoints four sites in the north Atlantic and five sites in the south Atlantic that are high-risk areas for leatherback turtles.  These high-risk sites include the economic zones shared by 12 different countries including the US and UK.  In these economic zones, many of which overlap with high-risk turtle zones,  longlines are cast regularly for tuna and other commercial fishing occurs here.

Action is being taken to protect the populations of these leatherbacks in the Atlantic, because the populations in the Pacific Ocean have nearly been wiped out and are considered critically endangered by the International Union for the Conservation of Nature.  Another scientist named Matthew Witt said that reversing the trend in the Pacific is almost impossible, but with his research they are trying to prevent this from happening in the Atlantic. 

His team was able to provide satellite data from over 100 turtles, showing their standardized tracks and also including longline-fisheries data to identify areas of low, medium and high interaction between turtles and humans.  The team then made a map that covers the Atlantic in a grid with squares that are 5 degrees latitude by 5 degrees longitude. 

Then, Rebecca Lewison, a conservation ecologist, backed up Witt’s team research by stating that his analysis makes it harder for governments to ignore the danger that bycatch poses to migratory species, including the leatherback turtles.  She also pointed out that ocean-wide scales like this one have to be taken into consideration if people are serious about preventing the extinctions of pelagic species. 

In summary, these scientists are all working together to prevent the bycatch of migratory species.  If they know where the turtles and other species are regularly found, fisherman can reduce bycatch by making better decisions on where to fish.  Maps like the one created in this study from satellite data can be used as a tool to prevent fisherman bycatch.  Longlines and other coastal fishing gear such as trawls pose the greatest risk to turtles, and future research can be done to incorporate these dangers into the maps as well. 

Friday, February 14, 2014

A quieting ocean: Unintended consequences of fluctuating economy.

            Climate change, conservation, energy, overpopulation, and pollution may be the most talked about environmental issues today. Public leaders have even down played some and voters saying, “it is junk science” or “it can be improved all the time.” Well, out all of the ones I have mentioned, I think it would be hard for anybody to down play pollution. What do you think of when you hear the word pollution? For me it is the Cuyahoga River. It caught on fire not once, but twice! It made Cleveland infamous though and it carries on today. It did spark a progression for change though. The Clean Water Act established better standards for our waterways. However, there is a different kind of pollution that does not get as much attention as say air or water. Do you ever think how noisy our environment is? How do you handle noise? Do you find noise disrupting at all?

            Lets delve a little deeper. What do you think about ocean noise? Have you ever thought about it? Mind you, we are terrestrial organisms, but marine organisms suffer the same implications from noise pollution as we do. In a 2012 publication, scientists looked at ocean noise and found correlations between ship noise, economic trends, and regulations on the shipping industry.

            Increased ocean noise poses a potential threat to marine animals that depend on sound for a myriad of ecological functions. This study was trying to better understand and reduce noise in marine habitats. The researchers used statistical correlations between regional commercial ships (ships that stayed close to California) and measured low-frequency sounds they emitted. They first looked at these ships when the economy sank (no pun intended) and then when regulations from the California legislator enacted new rules on the shipping industry. They were able to evaluate the trade-offs (and the economic costs) in noise pollution reduction with economic drivers to make additional efforts in reducing noise in the ocean.

            In the end, the statistical analysis the scientist did revealed small reductions in noise frequency with the changing economy and commerce regulations. Specifically, when one ship a day did not sail, one decibel was decreased in the area in in question. During the economic slump, noise levels were significantly reduced by about 40 hertz. They did not notice any significant change in noise levels when new regulations were impose. They did notice the great costs regulations impose on shipping (roughly $19 billion). The scientist point out that legislation needs to be focused on how ships are built and not on regulating how they run.

            In summary, the researchers focus on low-intensity, chronic noise, rather than high-intensity, short duration noise. Determining the ecological and organismal impact of these noises is difficult to document damages. This is due in large part to a very large habitat (the ocean) and organisms do not stay in one place for long. Physiological impacts are also a concern. However, as research on ocean noise continues, we will be better to evaluate it and find solutions that reduce them significantly to the point were oceanic impacts will be minimal (hopefully nothing).

Source: McKenna et. Al,: A quieting ocean. J. Acoust. Soc. Am. 132, September 2012.