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Sunday, October 24, 2010
Quotes of the Day
The scientific observer of Nature is a kind of mystic seeker in the act of prayer.
(Muhammad Iqbal)
(Muhammad Iqbal)
Saturday, July 17, 2010
SPECIES OF THE DAYHuso huso (Beluga Sturgeon)
The Beluga Sturgeon, Huso huso, is listed as ‘Endangered’ on the IUCN Red List of Threatened Species™. Also known as the Giant Sturgeon, it is the largest sturgeon in the world, and the largest freshwater fish in Europe, where it occurs primarily in and around the Caspian, Black, and occasionally in the Adriatic and Mediterranean Seas.
Overfishing, habitat loss and pollution threaten the survival of the Beluga Sturgeon. Its eggs are highly prized as beluga caviar, and illegal fishing is reported to be common. Pollution, dams and silting can cause habitat destruction by damaging coastal waters and altering river courses. For example, the Volgograd Dam in Russia has effectively blocked access to almost all of the species’ spawning grounds along the Volga River.
The majority of the Beluga Sturgeon population is now supported artificially, with hatcheries thought to be the sole reason the species still survives in the Caspian Sea. The United States is the biggest importer of beluga caviar, and has now listed the species as ‘Threatened’ under the Endangered Species Act, suspending imports.
The Beluga Sturgeon, Huso huso, is listed as ‘Endangered’ on the IUCN Red List of Threatened Species™. Also known as the Giant Sturgeon, it is the largest sturgeon in the world, and the largest freshwater fish in Europe, where it occurs primarily in and around the Caspian, Black, and occasionally in the Adriatic and Mediterranean Seas.
Overfishing, habitat loss and pollution threaten the survival of the Beluga Sturgeon. Its eggs are highly prized as beluga caviar, and illegal fishing is reported to be common. Pollution, dams and silting can cause habitat destruction by damaging coastal waters and altering river courses. For example, the Volgograd Dam in Russia has effectively blocked access to almost all of the species’ spawning grounds along the Volga River.
The majority of the Beluga Sturgeon population is now supported artificially, with hatcheries thought to be the sole reason the species still survives in the Caspian Sea. The United States is the biggest importer of beluga caviar, and has now listed the species as ‘Threatened’ under the Endangered Species Act, suspending imports.
Sunday, March 21, 2010
Popular Nanoparticle Causes Toxicity in Fish, Study Shows
Tested on fathead minnows -- an organism often used to test the effects of toxicity on aquatic life -- nanosilver suspended in solution proved toxic and even lethal to the minnows. When the nanosilver was allowed to settle, the solution became several times less toxic but still caused malformations in the minnows.
"Silver nitrate is a lot more toxic than nanosilver, but when nanosilver was sonicated, or suspended, its toxicity increased tenfold," said Maria Sepúlveda, an assistant professor of forestry and natural resources whose findings were published in the journal Ecotoxicology. "There is reason to be concerned."
Sepúlveda and doctoral student Geoff Laban exposed fathead minnows to nanosilver at several stages of their development, from embryo to the point where they swim up from the bottom of their habitats to eat for the first time. Even without sonication, nanosilver caused malformations that included head hemorrhages and edema, and ultimately proved lethal.
Using electron microscopy, Sepúlveda was able to detect nanosilver particles measuring 30 nanometers or less inside the minnow embryos. Thirty nanometers is more than 3,000 times smaller than the diameter of a human hair.
"These nanosilver particles are so small they are able to cross the egg membranes and move into the fish embryos in less than a day," Sepúlveda said. "They had a potentially high dose of silver in them."
Nanosilver is growing in popularity as a component of many products. It is used to kill bacteria in goods such as odor-control clothing, countertops, cutting boards and detergents. Currently, there are few regulations for nanosilver's applications in products, but Ron Turco, professor of agronomy and the paper's co-author, said the Environmental Protection Agency is reviewing the situation.
Turco also indicated there has been little work done to estimate the current level of nanosilver being released into the environment.
"Silver has been used in the past as an antimicrobial agent. It's a known toxicant to microorganisms," he said. "Nanosilver is being considered by the EPA for environmental exposure profiling, much like a pesticide."
Turco said it's unclear how nanosilver exposure might affect human health; however, he said that silver solutions have been considered by some to be a probiotic, and low dosages are sometimes consumed for intestinal health.
"The use of nanosilver could provide a number of sanitary benefits if used properly," Turco said. "However, the indiscriminate inclusion of nanosilver into products to simply allow them to say they are antimicrobial is creating a cautionary issue."
"Silver nitrate is a lot more toxic than nanosilver, but when nanosilver was sonicated, or suspended, its toxicity increased tenfold," said Maria Sepúlveda, an assistant professor of forestry and natural resources whose findings were published in the journal Ecotoxicology. "There is reason to be concerned."
Sepúlveda and doctoral student Geoff Laban exposed fathead minnows to nanosilver at several stages of their development, from embryo to the point where they swim up from the bottom of their habitats to eat for the first time. Even without sonication, nanosilver caused malformations that included head hemorrhages and edema, and ultimately proved lethal.
Using electron microscopy, Sepúlveda was able to detect nanosilver particles measuring 30 nanometers or less inside the minnow embryos. Thirty nanometers is more than 3,000 times smaller than the diameter of a human hair.
"These nanosilver particles are so small they are able to cross the egg membranes and move into the fish embryos in less than a day," Sepúlveda said. "They had a potentially high dose of silver in them."
Nanosilver is growing in popularity as a component of many products. It is used to kill bacteria in goods such as odor-control clothing, countertops, cutting boards and detergents. Currently, there are few regulations for nanosilver's applications in products, but Ron Turco, professor of agronomy and the paper's co-author, said the Environmental Protection Agency is reviewing the situation.
Turco also indicated there has been little work done to estimate the current level of nanosilver being released into the environment.
"Silver has been used in the past as an antimicrobial agent. It's a known toxicant to microorganisms," he said. "Nanosilver is being considered by the EPA for environmental exposure profiling, much like a pesticide."
Turco said it's unclear how nanosilver exposure might affect human health; however, he said that silver solutions have been considered by some to be a probiotic, and low dosages are sometimes consumed for intestinal health.
"The use of nanosilver could provide a number of sanitary benefits if used properly," Turco said. "However, the indiscriminate inclusion of nanosilver into products to simply allow them to say they are antimicrobial is creating a cautionary issue."
Sunday, February 14, 2010
Long-Distance Migration Shapes Butterfly Wings
As part of a National Science Foundation and UGA-funded study, researchers in the Warnell School of Forestry and Natural Resources and the Odum School of Ecology examined the size and shape of monarchs from migratory and non-migratory populations using sophisticated computer imaging that was able to measure precise details about the insects' wings. Warnell doctoral candidate Andy Davis and Odum Associate Professor Sonia Altizer compared migratory monarchs from the eastern and western U.S. to those in Hawaii, Costa Rica, South Florida and Puerto Rico that do not migrate. They also measured the wings of lab-grown monarchs to rule out environmental causes of differences in size and shape, and to demonstrate a genetic basis for variation in wing traits among individual monarchs. Altizer and Davis' findings were recently published in the online edition of the scientific journal Evolution.
The findings in monarchs were consistent with previous studies comparing migratory and non-migratory bird species, which indicate that the best shape for long-distance flight involves long wings with a narrow tip to help reduce drag. In addition to their findings on wing size and shape, the team also found that monarchs from the two migratory populations in the U.S. differed in body size, suggesting that each population could have adapted to the demands of migration in subtly different ways. Larger bodies might help eastern monarchs, with their much longer migration, carry fat deposits to fuel the long journey and five-month overwintering period in Mexico.
Thursday, January 21, 2010
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