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Toys, refrigerators, washing machines, socks—more and more products contain silver nanoparticles. It’s no wonder: These particles, which measure less 100 nanometers (smaller than a single HIV virus), can kill microbes on contact. But, researcher Darin Furgeson says, nanosilver can also escape into ecosystems and cause serious damage to fish embryos. Furgeson’s team published its results in the journal Small.

In one new experiment, Furgeson, a professor of pharmaceutical sciences, exposed zebrafish embryos to silver nanoparticles in a laboratory, and found that some died and others were left with dramatic mutations. “Some of the fish became extremely distorted, almost making a number nine or a comma instead of a linear fish,” he said [Scientific American]. Eyes, tails, and other body parts turned out malformed in the fish that survived.

Just how much nanosilver gets into the environment? A separate study from Environmental Science & Technology washed nine kinds of nanosilver-containing textiles, including some “anti-bacterial and anti-odor socks” that are already on the market. The researchers found that anywhere from less than 1 percent to as high as 45 percent of the silver came out in the first wash. Most of the silver was in the form of coarse particles of greater than 450 nanometers, suggesting that mechanical stress in the washing machine was responsible for most of the release [The New York Times], and that the nanoparticles might have aggregated to reach that size.

Those nanoparticles flushed out by a washing machine can end up in both fish habitats and drinking water supplies. Furgeson says his fish experiments could help show whether nanosilver is a health concern for humans, too. “Zebrafish have similar tissues and organs to us,” Furgeson said. “They don’t have lungs, but they do have a liver, kidneys and heart – though it is only two chambered – and they have a blood-brain barrier” [Scientific American].

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Image: Wiki Commons / Kristof vt

Atlantic bluefin tuna populations have declined so drastically that trade in the fish should be completely outlawed, says a new report. The population of the Atlantic tuna, a sushi staple, is now about 15 percent of the original stock size, says International Commission for the Conservation of Atlantic Tunas’ (ICCAT). The report has delighted conservation groups, who have criticized ICCAT’s regulation policies. The report was triggered by Monaco’s recent proposal to ban international trade in the Atlantic bluefin under the Convention on International Trade in Endangered Species (CITES) – a proposal that has gathered support from several other European countries [BBC News].

ICCAT has a history of setting quotas higher for the fish than scientists say is safe, while CITES seems to take a more proactive approach.Atlantic bluefin tuna are mainly caught from countries around the Mediterranean Sea, but most of the meat is consumed in Asia, particularly Japan. Japan has previously argued that commercial fish species should be controlled by bodies like ICCAT rather than CITES [BBC News]. In Japan, the fish are so highly prized that a single giant tuna can sell for more than $100,000 at the wholesale fish market. ICCAT will meet in 10 days to discuss the report.

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Image: Wikimedia Commons

Snooty wine pairing rules, such as the edict that one must only drink white wine with fish, now have a little data behind them, according to a new study. Researchers found a correlation between the high iron content of red wine and a nasty, fishy aftertaste when the reds are sipped with seafood. In the experiment, tasters ate a bit of scallop, tasted some wine and evaluated the aftertaste on a scale of 1 to 4. The diners found the unpleasant aftertaste was more intense with wines that had a higher iron content, the researchers say [Los Angeles Times]. The researchers were able to block the aftertaste by adding a compound that masks the iron.

The iron content of a wine depends on the composition of the soil in which the grapes were grown, the dust on the berry, contamination during harvesting, transportation, and crushing, and the conditions during fermentation [Telegraph]. The new research, published in Journal of Agricultural and Food Chemistry, suggests that some low-iron red wines are OK to drink with fish. While red wines tend to have more iron than whites, it varies according to the type of grape, country of origin, and vintage.

But the iron is only half the story. The researchers report that they haven’t yet isolated the compound in the scallops that reacts with the wine, but they suspect it’s an unsaturated fatty acid, which could be breaking down rapidly and releasing the decaying fish smell when exposed to iron [ScienceNOW Daily News].

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Image: flickr / yashima

Nissan is looking to schools of fish to learn about how to help people reduce car crashes and traffic jams. The car company developed tiny robots that move in fish-like groups of up to 7 without bumping into each other. Each uses a laser range-finder to measure the distance between obstacles. The data is constantly shared between peers via radio, allowing the group to travel as a “shoal” without bumping into each other. The technique allows the cars to travel side-by-side or quickly switch direction as a group [BBC News]. The robot is dubbed Eporo, which stands for Episode O (Zero) Robot, meaning zero episodes, or accidents, and zero emissions.

This is Nissan’s second attempt at designing a crash avoidance system based on animal behavior. Their last attempt was the BR23C robot, modeled after the anti-collision behavior of bumblebees (check out a video of the bee based bot here). The Eporo, however, imitates three rules of fish movement: avoiding crashes, traveling side by side, and keeping close to other members of the school [CNET]. Nissan plans to unveil the Eporo at the Ceatec conference in Tokyo on October 6. 

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Image: Nissan

In a landmark concession that will likely lead to the largest dam-removal effort in U.S. history, an electrical utility company has agreed to destroy four dams on the Klamath River to help migrating salmon and steelhead. The dams won’t be decommissioned until 2020 and there are still regulatory hoops to jump through, but fishermen and environmentalists are delighted by the development. “We’re about to make changes to the Klamath Basin that will be observable from space,” said Craig Tucker of the Karuk tribe, which traditionally fished for salmon [Los Angeles Times].

The Klamath River, which winds through Southern Oregon and eventually reaches California’s Pacific coast, was once home to one of the most vibrant salmon runs in the West. But since the first dam was erected in 1908, the region has been host to a nasty battle over water rights, with wildlife and commercial fishers ultimately bearing the worst scars as regulators were forced to repeatedly close salmon fishing along 700 miles of the Oregon-California coast [Greenwire]. The removal of the dams’ will open 300 miles of river to the salmon.

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Image: flickr / patrickmccully

Scientists have located a biological dimmer switch in a species of electric fish that uses electricity during everything from swimming to mating. The switch comes in handy when they don’t need to be electrified; during the day, the fish turn their current down to save energy for other activities, according to a new study in PLoS Biology. That means that the South American river fish, Sternopygus macrurus, is a natural practitioner of energy efficiency. It can reshape the charged-molecule channels in its electricity-producing cells to tone down its electrical signature within a matter of minutes [Wired.com].

Scientists found the dimmer switch in the membranes of cells called electrocytes within this electric organ. The switch takes the form of sodium channels that the fish can insert and remove from the electrocyte membranes. More sodium channels mean a stronger electric impulse [LiveScience]. Because the energy is expensive to produce for the fish, they do what the rest of us do when energy gets expensive–turn it off. The fish keep sodium channels on stand-by in the electric cells so they can switch the electricity back on in a moments notice if something spooks them.

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Image: flickr / walknboston

The tiny island nation of Palau has taken a big step to protect the ocean’s endangered sharks, by designating all of its territorial waters a shark sanctuary within which all commercial shark fishing is prohibited. Palau’s president, Johnson Toriboing, announced the plan at a meeting of the UN General Assembly last Friday. Sharks are increasingly under threat as the demand for shark-fin soup—a delicacy in many Asian countries—has risen worldwide. “The need to save the ocean and save sharks far outweighs the need to enjoy bowls of soup,” Toriboing said [National Geographic News].

Palau consists of about 200 small islands in the Pacific Ocean to the east of the Philippines; its expansive marine territory spans 230,000 square miles, an area about the size of Texas. About 130 species of rare sharks either make their homes or pass through these waters, including hammerheads, leopard sharks, and reef sharks, as well as the related stingrays.

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Even European eels enjoy a trip to the Bahamas, for mating season of course. The eel travels thousands of miles to the Sargasso Sea, in the Atlantic Ocean near the Bahamas, just to get a little action. Scientists wanted to see what the little eels were up to on their trek, so they equipped a few with satellite tags and tracked their journey, which surfaced in Science this week. The tags allowed researchers to follow 22 eels for the first 1,300 kilometers of their trek from the coast of Ireland to mating grounds near the Bahamas. Understanding the details of the eels’ journey may help to protect this critically endangered species, a favorite of sushi eaters [Science News].

The tags recorded location, speed, depth and direction of the eels for 6 months, before popping off and floating to the ocean’s surface to beam their data back to the laboratory. The researchers found the eels swim too slowly to get to the Sargasso Sea by the April spawning period. The researchers suggest this means the eels may gain speed and travel efficiency by entering the ocean currents that begin west of Africa and continue as part of the subtropical gyre system that flows to the Caribbean [BBC News]. The data also show that the eels swim in shallow, warm water at night and dive to depths of 3,200 feet during the day swims. Since the eels do not feed on their trip, scientists think swimming in warm water boosts metabolism, while the cold water helps slow sexual development until they reach the Sargasso Sea.

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Image: flickr / wwarby

Long gone are the days when a “robotic movement” meant something jerky, awkward, and stiff: The new robo-fish that have just been unveiled by engineers at the Massachusetts Institute of Technology swim through the water with sinuous grace. The flexible fish move naturally, as the motor in the middle initiates a wave that moves along the body and propels it forward. Real fish move in a similar fashion by contracting muscles on either side of their bodies [CNET]. The robo-fish are the descendants of Charlie the Robotuna, a large robot created at MIT in the 1990s that consisted of almost 3,000 parts. The new fish measure less than a foot long and use only 10 parts; researchers say the simple, durable fish are cheap to produce and hard to damage. To manufacture each robot, a single motor is placed in a fish-shaped mold before a liquid polymer is poured in and allowed to solidify. The continuous polymer casing prevents water from seeping in and damaging the motor, says Pablo Alvarado, an engineer who helped design the fish. “These materials are very resilient,” he said. “Water can’t do much to them and they can survive very high temperatures. Unless another fish eats them, they could go on and on” [Wired.com].

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A study that set out to determine the how many of the fish in our nation’s streams are contaminated with mercury came back with an ominous answer: quite possibly, all of them. Researchers from the U.S. Geological Survey sampled 34 species of fish at 291 stream sites across the country, and found mercury in every single fish they tested. “This study shows just how widespread mercury pollution has become in our air, watersheds, and many of our fish in freshwater streams,” U.S. Interior Secretary Ken Salazar said [Los Angeles Times].

A quarter of the fish had mercury levels that are considered unsafe for people who eat fish regularly, according to the Interior Department. The main source of mercury to most of the streams tested, according to the researchers, is emissions from coal-fired power plants. The mercury released from smokestacks rains down into waterways, where natural processes convert it into methylmercury — a form that allows the toxin to wind its way up the food chain into fish [AP]. But fish with high mercury levels were also found in Western areas that have been mined for gold or mercury.

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Image: flickr / kasperbs

The world’s fisheries may be seriously depleted, but a comprehensive new study shows that all is not lost–and suggests that when humans really put the effort into turning the tide, fish stocks can be returned to good health. The researchers found that efforts introduced to halt overfishing in five of the 10 large marine ecosystems they examined were showing signs of success. A combination of measures – such as catch quotas, no-take zones, and selective fishing gear – had helped fish stocks recover [BBC News].

The new study sprang from another report from marine ecologist Boris Worm in 2006, in which he made an alarming prediction: if current trends continue, by 2048 overfishing will have destroyed most commercially important populations of saltwater fish. Ecologists applauded the work. But among fisheries management scientists, reactions ranged from skepticism to fury over what many called an alarmist report [The New York Times]. Eventually the two groups agreed to collaborate on a study that would bring both their perspectives to the table, and which would determine the best ways to revive and manage the ocean’s fish stocks.

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Many animals depend on stealth to catch prey, but a small tentacled water snake resorts to downright trickery. That’s what a Vanderbilt University scientist found when he analyzed the way the snake captures fish, according to a study published in the Proceedings of the National Academy of Sciences.

The snake, which is native to Southeast Asia, takes advantage of a well-known reflex that fish possess. The mechanism occurs when a fish’s ear senses changes in water pressure due to movement nearby, which is all it takes to initiate the fish’s escape response, called the C-start — one of the most well studied neural circuits in vertebrates. Two large nerve cells, known as Mauthner cells, run along either side of the fish’s body and detect water disturbances. The cell closest to the signal will fire action potentials that stimulate trunk muscles on the opposite side of the body while simultaneously inhibiting the muscles on the near side. As a result, the fish turns away from the disturbance and flees. This whole process takes less than a tenth of a second [The Scientist]. The reflex causes the fish’s body to form a “C” as it turns away from the source of the underwater vibration—but in this case, that leads the fish right into the snake’s jaws.

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Human beings are increasingly making their homes on the coasts of continents, but this demographic shift is taking a toll on a sensitive coastal ecosystem that is often overlooked: seagrass meadows. A new analysis of seagrass abundance around the world found that 27 percent of these meadows have disappeared since 1879, and the rate of loss is accelerating. The study’s authors write: “Seagrass loss rates are comparable to those reported for mangroves, coral reefs and tropical rainforests, and place seagrass meadows among the most threatened ecosystems on earth….. Our report of mounting seagrass losses reveals a major global environmental crisis in coastal ecosystems, for which seagrasses are sentinels of change” [Nature News].

Endangered species expert Susanne Livingstone notes that despite these losses seagrass rarely makes it into the public consciousness. “It’s probably because they’re not as sexy [as corals], they’re not as attractive,” she says. “They’re just as ecologically important if not more so” [Nature News]. Seagrass meadows provide grazing for a variety of marine animals, including the green turtle and the manatee-like dugong. The coastal areas also serve as nurseries for fish; both coral reefs and commercial fisheries would feel the impact if seagrass meadows vanish.

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A tiny fish common in European streams may learn in a more sophisticated way than has ever been recorded among animals and which mimics human learning. In a study published in the journal Behavioral Ecology, scientists found that the nine-spined stickleback fish used the success and failures of their peers to gauge where they should seek food.

The fish were shown to display a type of learning known as “hill-climbing,” in which an entity continually looks for a better solution to a problem; in this case, one fish copied others that were more successful in finding food. Researchers caught 270 nine-spined sticklebacks in Leicester, England. The fish were organized into experimental groups. These fish groups then took turns as either free swimmers in a tank with worm-yielding feeders at the end, or as “learners” in a transparent, partitioned-off area of the specially designed tank. One of the two feeders released more worms than the other [Discovery News].

The first group of free-swimming fish quickly learned which feeder was full of worms, and were then put into the observers’ chamber. Next, researchers switched which feeder held the worms, and the fish in the observation tank watched the next fish group identify the new worm-filled feeder. After switching the two groups of fish again, the original group made a beeline for the feeder full of worms that their peers had fed from.

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From pandas to polar bears, animals have served as icons for wildlife conservation. Now a new documentary called The End of the Line has helped the bluefin tuna, an endangered species, swim into the limelight by highlighting the overfishing common in fisheries today. Based on a book by journalist Charles Clover, the film has spurred some retailers to remove bluefin from their menus and stores and even moved some celebrities to pose naked with the fish to advocate conserving them.

A growing demand for bluefin tuna, commonly found in sushi and now as endangered as the giant panda, has not only decreased the fish’s population, but also increased the number of undersized fish that are harvested, preventing the fish from reaching maturity. “Bluefin tuna has become the poster boy for the overfishing campaign. It’s on the buffers – it’s really on the slide down now,” Clover says.  “There are no large tuna anymore. There were bluefins of 250lb in Japanese fish markets when I went there four years ago – there are none now. A third of the catch is undersize” [BBC News].

The solution, experts say, doesn’t necessarily have to entail eschewing tuna altogether. Instead, consumers should stick to skipjack tuna, a more common variety, that has been caught using a method called pole-and-line, which avoids accidentally netting bluefish tuna and other sea life. Most commercial fishing operations that target skipjack use nets, Clover says, but “the skipjack run with all these other tuna species, like bigeye and bluefin. The skipjack are close to the surface and the bluefins swim further down, so there is often bluefin bycatch” [BBC News].

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