[LookOutSugarLake] Pesticides effects....

[Huguette - Imagine-ere]

Thought this would be of interest

Huguette



> From: bioserve-bounces at ml.islandnet.com [mailto:bioserve- 
> bounces at ml.islandnet.com] On Behalf Of Pamela Zevit
> Sent: Sat, January 27, 2007 12:41 PM
> To: BiologistsNetBC
> Subject: [Bioserve] common pollutants impact fish "scents" abilities
>
> Some related aquatic science and land use planning items:
>
> Pathways to Resilience: Sustaining Pacific Salmon in a Changing  
> World; Oregon Sea Grant will host an interdisciplinary conference 
> —"Pathways to Resilience: Sustaining Pacific Salmon in a Changing  
> World"—in Portland, Oregon, April 3-5, 2007. The meeting is a forum  
> for exploring the concept of resilience and its application to  
> ecosystem management and salmon recovery.  Further details about  
> meeting location, registration, topics for invited and contributed  
> papers, and poster sessions are posted at the following website:  
> http://oregonstate.edu/conferences/resilience/ . Coast Range News  
> is a service of the Coast Range Association (CRA). The CRA is a  
> regional advocacy organization with a mission of building just and  
> sustainable communities that provide for people and the natural  
> world. www.coastrange.org
> Aquatic Non-Scents
>
> Repercussions of water pollutants that mute smell
>
> Janet Raloff
>
> People complain about the way that fish smell. But it's the fish  
> that should be doing the grumbling. In pristine waters, the animals  
> smell quite well, thank you. Those tiny holes near fishes' mouths  
> are, in fact, nostrils through which the animals draw in water to  
> pump over olfactory nerves. By distinguishing scents, fish find  
> food and mates and avoid predators.
>
>
> These rainbow trout and some other aquatic creatures can  
> temporarily lose their sense of smell—and ability to detect mates,  
> food, and predators—when exposed to any of several common water  
> pollutants.
> Getty Images
>
>
> Studies decades ago, for instance, showed that mechanically  
> plugging the nostrils of adult salmon prevented them from locating  
> their natal streams when they attempted to return home to spawn.  
> The fish as juveniles had recorded memories of smells as they went  
> to sea. Without detecting the olfactory signposts, the fish  
> couldn't retrace their routes, says Nathaniel L. Scholz, a  
> zoologist at the National Oceanic and Atmospheric Administration's  
> (NOAA's) Northwest Fisheries Science Center in Seattle.
>
> In a series of studies over the past 6 years, his group has  
> demonstrated that metals and pesticides—at concentrations commonly  
> found in streams—can impair a salmon's sense of smell just as  
> effectively as plugging the nostrils did. Meanwhile, other  
> scientists have shown that such pollutants block the sense of smell  
> in other organisms.
>
> "What we're finding," says Scholz, is that "even short-term  
> exposure to many of these pollutants—on the order of hours—can  
> interfere with olfaction."
>
> Researchers have reported that the impairment can disrupt the  
> animals' normal behaviors in several ways. Fish use their keen  
> sense of smell not only to navigate dark and cloudy waters but also  
> to nose out scents indicating danger, such as chemicals from a  
> predators' skin.
>
> The studies are establishing that aquatic animals exposed to  
> pollutants miss chemical cues that have life-and-death  
> consequences, says ecotoxicologist Gregory G. Pyle of Nipissing  
> University in North Bay, Ontario.
>
>
> Pesticidal nose plugs
>
> North America's most widely used herbicide blunts a fish's sense of  
> smell, according to work by Keith Tierney and his colleagues at  
> Simon Frasier University in Burnaby, British Columbia. The  
> herbicide is sold under a number of trade names, including Roundup.
>
>
> NOSE JOB. Probes in this fish's nostrils       measure neurons'  
> ability to pass a scent signal to the brain. Pollutants such as  
> copper and several pesticides shut down that signaling.
> NOAA
>
>
> A 30-minute exposure to a 1 parts per billion (ppb) concentration  
> of atrazine reduced the activity of olfactory neurons in coho  
> salmon (Oncorhynchus kisutch) by 11 percent, the researchers  
> reported last November at the annual meeting of the Society of  
> Environmental Toxicology and Chemistry (SETAC) in Montreal. The  
> animals' neural responses to alarm odors dropped by 45 percent.  
> Higher doses of the herbicide triggered greater losses in smell;  
> 100 parts per million atrazine eliminated any response to a  
> predator's scent. River concentrations up to 20 ppb can occur  
> briefly near farms that apply it, says Tierney.
>
> Pure glyphosate, the active ingredient in atrazine, caused similar  
> changes in salmon olfaction, although only at far higher doses than  
> were required of the commercial herbicide formulation. At the  
> November SETAC meeting, these researchers presented data showing  
> that atrazine was 100 times as powerful at blocking fishes' sense  
> of smell as was an equal quantity of pure glyphosate.
>
> Atrazine contains a variety of ingredients added to glyphosate to  
> increase the herbicide's adhesion to leaves and to retard its  
> breakdown. Although these ingredients are listed as inert  
> components on herbicide labels, Tierney's team concludes that they  
> aren't inert as far as fish olfaction is concerned.
>
> "I'd like to find out what those inerts are," Tierney says, but he  
> notes that pesticide manufacturers regard them as part of their  
> proprietary recipes.
>
> Tierney isn't alone in his concern over supposedly inert  
> ingredients. Some "4.1 billion pounds of inert [pesticide]  
> ingredients are applied annually" to the U.S. environment,  
> Christian E. Grue of the University of Washington in Seattle and  
> his colleagues reported at the SETAC meeting.
>
> Because these compounds aren't lethal to untargeted organisms, they  
> don't require identification on labels, the Seattle researchers note 
> —even though the inerts may exert a subtle but substantial toxic  
> effect on aquatic life. Grue argues that "a new regulatory strategy  
> is needed," which would require toxicity analyses of any supposedly  
> inert ingredients.
>
> Atrazine isn't the only chemical pesticide that can suppress a  
> fish's ability to smell. Tierney's group showed that at exposures  
> of about 10 ppb, the fungicidal wood-preservative known as IPB  
> turned off olfaction in coho salmon. The researchers described that  
> finding in the August 2006 Aquatic Toxicology.
>
> They also reported in the October 2006 Environmental Toxicology and  
> Chemistry that the insecticide endosulfan and the herbicides  
> trifluralin and 2,4-D can impair a fish's sense of smell.
>
> Scholz' group, too, has made contributions to the list of  
> pesticides that affect fish olfaction. Six years ago, that team  
> showed that diazinon significantly impaired responses by Chinook  
> salmon (Oncorhynchus tshawytscha) to alarm scents and reduced their  
> success in finding their natal pools.
>
> More recently, Scholz' team has shown that low concentrations of  
> the insecticide chlorpyrifos can impair olfaction in coho salmon  
> and that the insecticide esfenvalerate can trigger abnormal neural  
> signals in response to food scents.
>
>
> Copper masks
>
> Copper runs off agricultural lands, lawns, and urban streets. It's  
> an active ingredient in many pesticides, and brake pads often shed  
> copper as they wear down. Dissolved copper diminishes a fish's  
> sense of smell, several researchers reported at the SETAC meeting.
>
>
>
> ROSY. This rosette, from inside the nostril of a coho salmon,  
> contains the odor-sensory neurons that various pollutants can impair.
> C.Stehr, NOAA Fisheries
>
>
> Scholz' team, for instance, reported that just 3 hours of exposure  
> to waterborne copper reduced responses of juvenile coho salmon to a  
> typical alarm odor, a scent that came from the skin of a wounded  
> coho. Such chemical alarms typically make young coho dive for cover.
>
> Juvenile salmon that had been kept in clean tanks reacted properly  
> to the cue. They stopped swimming, ignored food, and sought refuge.  
> Other juveniles, which had spent 3 hours in copper-tainted water,  
> swam placidly and continued feeding after researchers spiked their  
> water with an alarm scent. Scholz characterizes the copper-treated  
> fish as "totally oblivious" to this whiff of danger.
>
> The scientists went further in establishing that copper impairs the  
> sense of smell. From several fishes' nostrils, they recorded  
> electrical signals carrying information to the brain from olfactory  
> neurons. Compared with the untreated fish, copper-treated coho  
> produced much weaker—or no—responses to the alarm scents. Scholz  
> says that his group found "a very tight relationship" between the  
> fishes' behavior and olfactory neuron signals.
>
> Reehan Mirza, Pyle, and their colleagues at Nipissing University  
> have witnessed the same phenomenon in fish exposed to copper in the  
> wild. These Canadian researchers worked with yellow perch (Perca  
> flavescens) taken from Ontario lakes, some of which were  
> contaminated by runoff from a copper mine. "Fish from the clean  
> lakes responded to alarm cues," Mirza told Science News, "while  
> perch from the contaminated lakes did not."
>
> Mirza's team exposed the fish to chemicals extracted from the skin  
> of a wounded perch or the skin of a rainbow trout, a perch  
> predator. Odor sensitivity in perch from lakes with less than 2  
> parts per billion (ppb) copper was 2.5 times that in fish from  
> lakes containing at least 18 ppb copper.
>
> Dissolved copper also seems to prevent female fish from sizing up  
> prospective mates. In seeking males that are fat and healthy,  
> female fathead minnows (Pimephales promelas) assess a Romeo's  
> qualities "exclusively from chemical information," says Pyle.
>
> To test copper's effects on this aspect of smell, Pyle and his  
> colleagues raised males for a month on either a low- or a high- 
> calorie diet. The results were emaciated, sickly looking males and  
> specimens of minnow machismo.
>
> A male from each category was then placed at the end of each branch  
> of a Y-shaped maze. Egg-swollen females placed at the start of the  
> maze couldn't see their potential mates but could pick up the  
> males' scents. In nearly every case where the female had come from  
> a clean lake, she headed toward the larger male. Females from  
> copper-tainted lakes, by contrast, showed no preference between the  
> candidates.
>
> The researchers then built a glass cage in which the females could  
> see but not smell potential mates. In this case, females from both  
> the clean and copper-tainted lakes showed no preference for robust  
> males. Pyle concludes that females can't compensate visually for  
> their lack of smell.
>
> "This can have implications on the subsequent gene pool," he told  
> Science News. "If you're not picking the optimal mate, there's an  
> increasing probability that that next generation won't be as  
> successful in their environment."
>
>
> Beyond fish
>
> Pyle and his colleagues have also shown effects of copper-mine  
> runoff on leeches and water fleas. The team began investigating the  
> metal's impact on leeches after hearing reports from anglers who  
> observed that leeches, aquatic relatives of the earthworm, appeared  
> to inhabit only the lakes around Sudbury, Ontario, that weren't  
> polluted by copper-mine wastes.
>
> Pyle explains that the local leech, Nephelopsis obscura, is  
> "effectively blind—and therefore relies almost exclusively on  
> chemical information [scents] to locate food."
>
> The researchers collected leeches from clean lakes and then put  
> some in water with copper at concentrations of either 10 or 20 ppb.  
> After 2 to 16 days of such exposure, each leech was placed in a  
> clean-water tank containing a Y-shaped maze. One arm of the maze  
> was baited with beef liver.
>
> Copper-exposed leeches had trouble identifying the path to the  
> food, and the longer they had been exposed to the metal the less  
> likely they were to succeed. Leeches unexposed to copper invariably  
> found the meal unless the researchers laced the maze water with  
> copper. Then, Pyle notes, these leeches, too, swam "randomly, no  
> longer able to discriminate food scents."
>
> Even more telling, Pyle says, were tests in which his group placed  
> a leech in a fishbowl of clean water along with a dead minnow. If  
> the leech had been living in clean water, it immediately swam to  
> the fish and began feeding. However, leeches that had spent a week  
> in water with at least 5 ppb copper had trouble locating the minnow.
>
> Pyle says that some Sudbury-area lakes have up to 30 ppb copper  
> concentrations—and no leeches. Unable to smell their next meal, the  
> animals there may have all starved, he concludes.
>
> His team has also studied copper's effect on a tiny water flea  
> (Daphnia pulex)—a crustacean about 2.5 millimeters long—that serves  
> as the bottom rung on many lake-animal food ladders. Larvae of an  
> insect known as the phantom midge (Chaoborus americanus) are among  
> Daphnia's predators. The larvae release an odor when they feed on  
> the water fleas. Young Daphnia that pick up the scent respond, over  
> several days, by developing neck spines that make the tiny animals  
> too big for a larval midge's mouth.
>
> In lab tests, however, Daphnia housed in water containing as little  
> as 5 ppb copper developed few if any protective neck spines in  
> response to the midge scent.
>
>
> Growing concerns
>
> Pesticides typically reach streams via runoff when rains hit a  
> recently treated farm, forest, or lawn. Roadways, storm drains, and  
> paved and plowed land facilitate quick pollutant runoff into  
> surface waters, Scholz says. His NOAA team now simulates such  
> intermittent pollutant exposures.
>
> In these circumstances, a pollutant-induced shutdown of fishes'  
> sense of smell may last only a few hours. However, in some regions,  
> pulses of polluted storm water "may come through so frequently that  
> fish never effectively recover," Scholz says. Increasing runoff in  
> areas of growing urban and rural development may explain why salmon  
> are disappearing from streams throughout the West, he proposes.
>
> Pyle notes that pesticides and copper at concentrations similar to  
> those in the environment knock out olfactory communications in  
> every species tested to date—whether water fleas, leeches, or fish.  
> He told Science News, "The apparent ubiquity of this phenomenon is,  
> well, quite disturbing."
>
>
> If you have a comment on this article that you would like  
> considered for publication in Science News, send it to  
> editors at sciencenews.org. Please include your name and location.
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Huguette
250-547-0272
www.imagine-ere.ca



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