The Global Fool

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Farmed Salmon Develop Ear Deformities All Around the World
May31

Farmed Salmon Develop Ear Deformities All Around the World

By Roberta Attanasio Salmon farming is the fastest growing food production system in the world—accounting for 70 percent (2.4 million metric tons) of the market. Increasing demand is leading to the gradual development of responsible practices to minimize its negative impacts on the environment. Indeed, salmon farming is known to pollute the oceans, use toxic pesticides to control the spread of sea lice, foster diseases caused by viruses and bacteria, allow escapees, and deplete the stocks of forage fish—depending on the production region, 1.5 – 8 kilograms of wild fish are needed to produce one kilogram of farmed salmon. However, despite the development of the open and transparent production practices encouraged by the WWF in 2004, and currently managed by the Aquaculture Stewardship Council (ASC), salmon farming is plagued by numerous problems. A deadly algal bloom is killing millions of farmed fish salmon in Chile, causing a drop of 35% to 45% in exports this year. In addition, the recent research finding that farmed Atlantic salmon from Norway, Australia, Scotland, Canada and Chile are going deaf is both surprising and alarming, raising questions about animal welfare and conservation efforts. Farmed salmon have deformed otoliths (or fish earbones) and, as a result, poorer hearing. Otoliths are located behind a fish’s brain and are essential for hearing and balance, much like the inner ears of humans and other mammals. The typical structure of healthy otoliths is made up of calcium carbonate. However, in most farmed Atlantic salmon, the calcium carbonate is present in the otoliths in a different crystal form, leading to larger, lighter and more brittle structures. This deformity is very uncommon in wild fish. The researchers point out that the deformed earbones could be responsible for the low efficiency of conservation programs, thus explaining the origins of what, in the field, is considered a long-standing mystery. Every year, billions of captive-bred juvenile salmon are released into rivers worldwide to boost wild populations, but their survival is 10-20 times lower than that of wild salmon. The new finding may help explain this low survival rate. Hearing loss could prevent fish from detecting predators, and restrict their ability to navigate back to their home stream to breed. Researchers do not know what the triggering factor for earbone deformity is—they speculate it could be something in the fish’s diet, or a genetic component unique to the salmon selected to be farmed, or it could be related to their abnormally rapid growth rate. Salmon farming is a work in progress. Knowledge and experience, along with commitment to sustainable practices, are necessary for successful production. The unexpected finding of hearing loss in farmed salmon...

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Small Predator Diversity Plays a Significant Role in the Spread of Infectious Diseases
Mar23

Small Predator Diversity Plays a Significant Role in the Spread of Infectious Diseases

By Roberta Attanasio Biodiversity is a term coined to describe the diversity of all living things, from human beings to microorganisms. A New York Times editorial published almost two decades ago aptly describes the importance of the biodiversity concept: “Biodiversity is a hugely important concept that stresses the coherence and interdependence of all forms of life on earth and a new willingness to appraise the meaning of that interdependence, not just for humans but for every one of life’s component parts.” The editorial goes on to illustrate the alarming effects of biodiversity loss: “Biodiversity is a way of talking about what scientists have long understood and a way of reminding the rest of us of a cardinal fact: that we are standing in the midst of the earth’s sixth great extinction of diverse species, that this extinction is driven by us and that we are not now and will never be immune to its effects.” One of these effects is the worldwide spike in infectious diseases, as suggested by a study recently published in the journal Proceedings of the National Academy of Sciences. The study (Predator diversity, intraguild predation, and indirect effects drive parasite transmission) explores how the diversity of small predators shapes the transmission of parasites in wetlands. Lead author Jason Rohr said in a press release by Penn State: “In the last century, there has been an unprecedented global increase in infectious diseases and a concomitant decline in and homogenization of biodiversity. The controversial ‘dilution effect hypothesis’ suggests that the two phenomena might be linked, or that biodiversity often decreases disease risk.” The study, which included a series of laboratory experiments, field surveys and mathematical modeling, shows that — in presence of various species of dragonfly larvae — there is a reduction of frog infections caused by trematodes, which are parasitic flatworms also known as flukes. The dragonfly larvae are small predators that eat trematodes. Val Beasley, senior author of the study, said in the press release that various species of trematodes penetrate tadpoles. The trematodes sometimes kill the tadpoles. In other instances, the trematodes weaken them by causing tissue damage, kidney failure, or severe limb deformities while the tadpoles develop into frogs. He added that other vertebrate species commonly catch trematode infections from bodies of water. These vertebrate species include wildlife, domestic animals and humans — mostly children — who are commonly affected by schistosomiasis in tropical parts of the world. Schistosomiasis is a parasitic disease carried by freshwater snails infected with one of the five varieties of the parasite Schistosoma, a type of trematode. Although the worms that cause schistosomiasis are not found in the...

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Tasmanian Devils: Contagious Cancer Drives the Risk of Extinction
Dec05

Tasmanian Devils: Contagious Cancer Drives the Risk of Extinction

By Roberta Attanasio In November 2013, a team of biologists scattered 15 plastic cylinders in the fields of Maria Island, three miles off the east coast of the Australian island state of Tasmania. Each cylinder contained a healthy Tasmanian devil, a marsupial  species that until then lived only in Tasmania. Soon, the 15 devils emerged from the containers, becoming the first ever to inhabit Maria Island. The biologists were planning to take more devils to the island. Why? To establish a healthy colony, needed for the survival of the entire species. The Tasmanian devil is on the brink of extinction because of an unusual disease — a contagious cancer that is spreading very quickly. In some areas, more than 90% of the population has been wiped out. The disease is called Devil Facial Tumor Disease, or DFTD for short, and is characterized by malignant tumors — around the mouth and head — that behave as parasites and have caused an epidemic of cancer. The tumors are directly transmitted when the devils bite each other faces during fights — sometimes they bite off little pieces of tumor. When this happens, the cells reach the attacker’s bloodstream and, from there, its face. Once in the face, they start growing, producing a new tumor. Because the growth of tumors is not controlled by the devils’ immune system, the disease causes 100% mortality among infected devils. Tasmanian devils (Sarcophilus harrisii) are dog-sized carnivorous marsupials known for their black color, spine-chilling screeches and bad temper — they look and sound fierce. Today, the devil is a Tasmanian icon set to disappear. However, if the devils become extinct in Tasmania, the disease will disappear with them, as they are the only animals affected by this type of contagious cancer. At that point, the healthy devils from Maria Island could be introduced back in the wild.  Carl Zimmer wrote that when the tumor disease was first discovered in 1996, many scientists assumed it was caused by a rapidly spreading virus. Instead, in 2006, Anne-Maree Pearse and Kate Swift (Department of Primary Industries, Water and Environment in Tasmania), discovered something strange about the tumor cells. The chromosomes looked less like those in the animal’s normal cells and more like those in the tumors growing in other Tasmanian devils. Pearse and Swift proposed that the disease is transmitted when an infectious cell line is passed directly between the animals through bites they inflict on one another. They thought that the low genetic diversity and high degree of kinship among devils might help to reduce their immune response to cancer cells implanted during biting. In 2007, Katherine Belov and her collaborators published a study showing that the tumor DNA was similar in different animals,...

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Ivory Poaching Drives the Global Decline of African Elephants
Aug22

Ivory Poaching Drives the Global Decline of African Elephants

By Roberta Attanasio Poaching — the illegal killing of wild animals — is responsible for the death of tens of thousands of African elephants a year.  Poachers kill elephants to hack off the tusks, which are then sold to make valuable ivory trinkets, mostly for Asian markets.  In 2012, Jeffrey Gettleman wrote in the New York Times that Africa is in the midst of an epic elephant slaughter. How many African elephants, then, are slaughtered every year for their ivory? Results of a new study (Illegal killing for ivory drives global decline in African elephants) published a few days ago in the journal Proceedings of the National Academy of Sciences show that, between 2010 and 2012, an estimated 100,000 elephants have been killed in Africa by poachers. These killings result in population declines of wild African elephants on the order of 2 percent to 3 percent a year — a decline that is unsustainable and could lead to their extinction in 100 years or even less. Chris Thouless of the World Wildlife Fund in Windhoek, who wasn’t involved in the study, told the journal Science: “Some of the assumptions in the paper are quite conservative, and it is possible that the real situation is worse than indicated.” Indeed, the authors of the study believe that the impact of poaching could be higher than estimated — poachers target the largest adults, whose deaths decrease birth rates and disrupt social networks. Lead author George Wittemyer, from Colorado State University, told the BBC: “We are shredding the fabric of elephant society and exterminating populations across the continent.” The killing of the oldest and biggest elephants, explains Wittemyer,  “means removal of the primary breeding males and removal of family matriarchs and mothers. This leaves behind orphaned juveniles and broken elephant societies.” Let’s not forget that the highly endangered Asian elephants are also subjected to poaching. However, it is the extensive decline of African elephant populations that currently has a major influence on the global elephant decline. Elephants display levels of intelligence observed only in humans, chimpanzees, dolphins and other animals capable of higher forms of thinking. Unknown to many, elephants are forest gardeners — they are essential to seed dispersal and to maintaining tree diversity.  “Witnessing the killing of known elephants, some that we have followed since they were born, has been terrible,” said Wittemyer in a press release, “Our data has become the most sensitive barometer of change during this poaching epidemic. We needed to quantify the scale of killing and figure out how to derive rigorous interpretation of poaching rates.” The authors of the study conclude that solutions to this crisis require global action — we all...

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Minute 319: The Delta of the Colorado River Gets a New Life
Mar19

Minute 319: The Delta of the Colorado River Gets a New Life

By Roberta Attanasio For six million years, the Colorado River ran from the Rocky Mountains to the Gulf of California—through 1,450 miles of mountains, deserts, canyons, and the lush delta in Mexico. Now, it no longer reaches the sea. The once vast and fertile delta of the river is dry—a parched wasteland. In 1931, the United States Bureau of Reclamation built the first of a series of large dams along the lower Colorado River, which now provides water to two states in Mexico and 30 million people in seven U.S. states. Until the 1950s, the delta was still a network of freshwater and marine wetlands with meandering river channels—an opulent habitat for a very diverse and thriving wildlife. Then, things changed fast—the water slowed to a trickle. Peter McBride, author of The Colorado River: Flowing Through Conflict, said in 2010 “I spent two weeks walking the most parched, barren earth you can imagine. It’s sad to see the mighty Colorado River come to a dribble and end some 50 miles north of the sea.” There are good news, though—we may be getting back some of the lost opulence. Minute 319—an amendment to the 1944 Water Treaty between Mexico and the United States—calls for a pulse flow (a large one-time release of water) that will improve surface water and groundwater conditions as well as natural vegetation and wildlife. On March 23, the pulse flow will be released from Lake Mead, the largest reservoir in the United States, and will continue for nearly 2 months, sending water down the lowermost Colorado River. Although the pulse represents just 0.7% of the 18.5 billion cubic meters that once reached the gulf each year, research teams from United States and Mexico universities, agencies and environmental groups expect a quick response, as the newly released water creates new habitats for seedlings, while flushing salts from the soil.  After the pulse ends on May 18, researchers will measure seed germination and seedling survival at different time points. Later, they will rely on aerial photographs or satellite images to monitor tree growth. However, Minute 319 is expected to accomplish much more, as “It establishes new rules in sharing Colorado River water while providing immediate plans to address current challenges along the river during the next five years. Equally important, the pact sets the stage for how the two nations might work in the future to establish a long-term management policy for the Colorado River.” The amendment comes after years of negotiations and meetings. Now, the United States and Mexico, for the first time, have set criteria to share both water surpluses and water shortages. For example, Mexico has limited water storage capacity—thus, it will store...

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