ScienceDaily (Oct. 8, 2011) — Spanish researchers have discovered a rare mollusc in Antarctic waters that looks the same as limpets but is bigger in size than the species known to date. The specimen appeared in waters much further away from where this type of species is normally found.
A new species of mollusc that shares the same morphology as the limpet (Fissurellidae) and is 14 millimetres in length has been found in Antarctic waters. This discovery by a research team from the Ecology and Zoology Department of the University of Vigo, Spain has been published in The Nautilus and provides more information on the members of the Zeidora genus and their geographic distribution.
Cristian Aldea, co-author of the study, explains that "this genus belongs to a group which we know very little about. This group is made up of 14 species of which very few specimens have found."
Named Zeidora Antarctica, this 14 millimetre long specimen is much bigger than members of the same genus, who are not normally longer than 5 millimetres.
It was discovered at a depth of more than 600 metres in the Bellingshausen Sea in Antarctica -- a habitat with very different characteristics to that of other Zeidora species. Previously found specimens of this group live in tropical and warm waters. Out of all of them, eight species have been discovered in the Northern Hemisphere in the Caribbean, Japan, Panama and the Red Sea. Furthermore, six have been found in the Southern Hemisphere in places like the Galapagos Islands, Easter Island, Australia and New Zealand.
The specimen was found during the BENTART expedition of the Spanish National Antarctic Programme on board the Hespérides. Aldea recognises that he was not expecting "to find such a species on the trip since those that have already been discovered are known to be distributed from low (tropical) to medium latitudes with the closest becoming a species found in New Zealand."
Aldea states that "we carried out the description of the species based on the shell, given that no soft tissue could be found in the only caught specimen." These studies have allowed us to show, for instance, the number and size of ribs that the mollusc has. However, the morphology of its soft tissue was not revealed but "all of the characteristics taken from the shell indicate that it is a living species as opposed to a fossil species," according to the expert.
The discovered specimen is on display at the Madrid's National Natural History Museum (MNCN) and has been compared with other Zeidora naufraga Watson, Zeidora maoria Powell and Zeidora reticulata species that are on display at the London's Natural History Museum.
http://www.sciencedaily.com/releases/2011/10/111006084232.htm
Showing posts with label molluscs. Show all posts
Showing posts with label molluscs. Show all posts
Sunday, October 9, 2011
Sunday, June 5, 2011
Mass extinction victim survives! Snail long thought extinct, isn't
 |
| A view of Choccolocco Creek, Talledega County, Alabama, where a surviving population of the wicker ancylid limpet Rhodacmea filosa (insert, not to scale), was recently rediscovered. Credit: Paul Johnson, Alabama Aquatic Biodiversity Center |
ANN ARBOR, Mich.—Think "mass extinction" and you probably envision dinosaurs dropping dead in the long-ago past or exotic tropical creatures being wiped out when their rainforest habitats are decimated. But a major mass extinction took place right here in North America in the first half of the 20th century, when 47 species of mollusk disappeared after the watershed in which they lived was dammed.
Now, a population of one of those species—a freshwater limpet last seen more than 60 years ago and presumed extinct—has been found in a tributary of the heavily dammed Coosa River in Alabama's Mobile River Basin. Researchers from the University of Michigan, the Alabama Aquatic Biodiversity Center and the Kentucky State Nature Preserves Commission reported the rediscovery May 31 in the online, open-access journal PLoS One.
The story of Rhodacmea filosa's disappearance and reappearance is both a conservation success story and a cautionary tale for other parts of the world where rivers are being dammed, said Diarmaid Ó Foighil, professor of ecology and evolutionary biology and a curator at the U-M Museum of Zoology. It's also an example of how museum specimens collected generations ago can inform scientists of today.
Limpets are snails with shells shaped like caps rather than coils. They make their homes in the riffles and shoals of fast-flowing rivers and streams, where they graze on microscopic algae. When rivers are dammed, shoals and riffles are replaced with reservoirs, and the swiftly-moving water the limpets require is stilled.
The Mobile River Basin, a "global hotspot of temperate freshwater biodiversity," was extensively industrialized throughout the 20th century, and 36 major dams and locks were built. At the time, few thought much about preserving biodiversity. The prevailing attitude was, "What's not to like about getting electricity from a natural source—especially in impoverished, rural areas—and using that to drive industrialization?" Ó Foighil said. "The dams were seen as signs of progress."
But progress came at the expense of mollusks that were found only in that area and nowhere else in the world.
"Their habitat was destroyed in huge chunks," Ó Foighil said. The result: 47 of 139 endemic mollusk species were lost, representing a full one-third of all known freshwater mollusk extinctions worldwide.
Then, about 20 years ago, thanks to increased interest in and funding for conservation projects, biologists began searching patches of the drainage that weren't affected by damming, trying to find remnants of the original, rich fauna and save whatever still could be saved. At the Alabama Aquatic Biodiversity Center (AABC), a former catfish experimental research station has been converted into a captive breeding facility, with the aim of breeding survivors of the mass extinction and reintroducing them into unaffected parts of the watershed.
It was through those efforts that AABC director Paul Johnson discovered the surviving population of what he thought might be Rhodacmea filosa. But how does one definitively identify a species that hasn't been seen in decades? There are no other living members of the group with which to compare specimens.
That's where the U-M Museum of Zoology collection comes in. It just so happens that 100 years ago, biologists collected multitudes of mollusks from the Mobile River Basin—never envisioning the habitat destruction and resulting extinctions that were to come—and those specimens ended up in the U-M collection. Coincidentally, the mollusk portion of that collection was largely established by Bryant Walker, an early authority on—you guessed it—the limpet genus Rhodacmea. Furthermore, the last person to study Rhodacmea was a U-M graduate student, some 50 years ago.
Using century-old reference specimens, Ó Foighil, professor emeritus John Burch, graduate student Jingchun Li and collection coordinator Taehwan Lee were able to confirm the identity in addition to performing detailed morphometric and DNA analyses.
"This is very good news," Ó Foighil said. "With conservation biology, usually it's all gloom and doom, but this is one of those rare events where we have something positive to say."
But just because survivors have been found, does that mean the species can continue to survive?
"I think they can, because of two things," Ó Foighil said. "We have a persistent population in this little tributary, but we also now have in place the infrastructure for their captive breeding and reintroduction to other tributaries."
This snail tale might well serve as an object lesson, Ó Foighil said. "The industrialization of freshwater watersheds that happened across the U.S. in the last century is now happening all over the world. For instance, right now one of the most egregious examples is the ongoing damming of the Mekong, and there are likely thousands of endemic species there. Even though we're now more aware of this—of the negative downsides—when it comes to issues of economic development, freshwater biodiversity almost always loses."
In addition to Ó Foighil, Li, Lee, Johnson and Burch, the paper's authors include Ryan Evans of the Kentucky State Nature Preserves Commission. Funding was provided by the State Wildlife Grant Program, the U.S. Fish and Wildlife Service and the National Science Foundation.
http://ns.umich.edu/htdocs/releases/story.php?id=8426
Wednesday, May 25, 2011
Endangered gourmet sea snail could be doomed by increasing ocean acidity
Public release date: 25-May-2011
Increasing levels of ocean acidity could spell doom for British Columbia's already beleaguered northern abalone, according to the first study to provide direct experimental evidence that changing sea water chemistry is negatively affecting an endangered species.
The northern abalone--prized as a gourmet delicacy--has a range that extents along the North American west coast from Baja California to Alaska. Even though British Columbia's northern abalone commercial fisheries where closed in 1990 to protect dwindling populations, the species has continued to struggle, largely due to poaching.
To better understand the impact climate change — and specifically, increasing ocean acidity — has on this endangered species, UBC researchers exposed northern abalone larvae to water containing increased levels of CO2. Increases from 400 to 1,800 parts per million killed 40 per cent of larvae, decreased the size of larvae that did survive, and increased the rate of shell abnormalities.
"This is quite bad news, not only in terms of the endangered populations of abalone in the wild, but also the impact it might have on the prospects for aquaculture and coastal economics," says Christopher Harley, Associate Professor with the Department of Zoology and one of the authors of the study.
"And because the species is already thought to be limited by reproductive output and recruitment, these effects are likely to scale up to the population level, creating greater limits on population growth."
Average CO2 levels in the open ocean hover at 380 parts per million, a number which is excepted to increase slowly over the next century.
What concerns the researchers are the much higher spikes in dissolved CO2 that are already being observed along the BC coast, particularly in late spring and early summer when northern abalone populations are spawning.
The findings were published in the latest issue of the Journal of Experimental Marine Biology and Ecology.
"While we're looking at a single species that is culturally important as a source of food and artistic inspiration for many coastal Pacific Northwest First Nations, this information may have implications for other abalone species in other parts of the world," says Ryan Crim, lead author on the paper who conducted the research while a graduate student with the UBC Department of Zoology.
Other species of abalone are farmed around the world, principally in China, Taiwan, Japan and Korea. The black, white and pink abalone are also endangered on the west coast--red abalone are still an economically viable food species.
The study was funded by the Natural Sciences and Engineering Research Council of Canada and conducted in collaboration with the Bamfield-Huu-ay-aht Community Abalone Project, a small abalone hatchery in Bamfield which has subsequently gone out of business. The dual mission of the hatchery was to produce cultured abalone for high end restaurants, and to restore endangered abalone by culturing and releasing larvae and juveniles to the wild.
Harley and Crim will continue to work with the aquaculture industry to study the effects of acidification on oysters and other shellfish.
http://www.eurekalert.org/pub_releases/2011-05/uobc-egs052511.php
Increasing levels of ocean acidity could spell doom for British Columbia's already beleaguered northern abalone, according to the first study to provide direct experimental evidence that changing sea water chemistry is negatively affecting an endangered species.
The northern abalone--prized as a gourmet delicacy--has a range that extents along the North American west coast from Baja California to Alaska. Even though British Columbia's northern abalone commercial fisheries where closed in 1990 to protect dwindling populations, the species has continued to struggle, largely due to poaching.
To better understand the impact climate change — and specifically, increasing ocean acidity — has on this endangered species, UBC researchers exposed northern abalone larvae to water containing increased levels of CO2. Increases from 400 to 1,800 parts per million killed 40 per cent of larvae, decreased the size of larvae that did survive, and increased the rate of shell abnormalities.
"This is quite bad news, not only in terms of the endangered populations of abalone in the wild, but also the impact it might have on the prospects for aquaculture and coastal economics," says Christopher Harley, Associate Professor with the Department of Zoology and one of the authors of the study.
"And because the species is already thought to be limited by reproductive output and recruitment, these effects are likely to scale up to the population level, creating greater limits on population growth."
Average CO2 levels in the open ocean hover at 380 parts per million, a number which is excepted to increase slowly over the next century.
What concerns the researchers are the much higher spikes in dissolved CO2 that are already being observed along the BC coast, particularly in late spring and early summer when northern abalone populations are spawning.
The findings were published in the latest issue of the Journal of Experimental Marine Biology and Ecology.
"While we're looking at a single species that is culturally important as a source of food and artistic inspiration for many coastal Pacific Northwest First Nations, this information may have implications for other abalone species in other parts of the world," says Ryan Crim, lead author on the paper who conducted the research while a graduate student with the UBC Department of Zoology.
Other species of abalone are farmed around the world, principally in China, Taiwan, Japan and Korea. The black, white and pink abalone are also endangered on the west coast--red abalone are still an economically viable food species.
The study was funded by the Natural Sciences and Engineering Research Council of Canada and conducted in collaboration with the Bamfield-Huu-ay-aht Community Abalone Project, a small abalone hatchery in Bamfield which has subsequently gone out of business. The dual mission of the hatchery was to produce cultured abalone for high end restaurants, and to restore endangered abalone by culturing and releasing larvae and juveniles to the wild.
Harley and Crim will continue to work with the aquaculture industry to study the effects of acidification on oysters and other shellfish.
http://www.eurekalert.org/pub_releases/2011-05/uobc-egs052511.php
Monday, April 25, 2011
Rock-eyed sea creature
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| This lined chiton, whose anterior end is to the right, lives about 50 feet below the water's surface near Whidbey Island, Washington. |
A tiny sea mollusk uses eyes made of a calcium carbonate crystal to spot predators lurking above, researchers say of the first such rocky lenses found in the animal kingdom.
While scientists had discovered the hundreds of eye-like structures on the surface of this armored mollusk, called a chiton, decades ago, they didn't know what they were made of or whether they could actually see objects or just sensed light.
"Turns out they can see objects, though probably not well," said study researcher Daniel Speiser, who recently became a postdoctoral fellow at the University of California, Santa Barbara.
http://www.thedailystar.net/newDesign/news-details.php?nid=182144
Saturday, February 12, 2011
Oysters Are 'Functionally Extinct'
The Huffington Post
Dean Praetorius
First Posted: 02/ 4/11 04:21 PM
Oysters aren't disappearing from the dining table anytime soon, but they may be disappearing from our oceans.
A recent study published in BioScience has shown that the mollusks, declared "functionally extinct," are disappearing quickly as 85 percent of their reefs have been destroyed through disease or over-harvesting, according to the AFP. 75 percent of the remaining wild oysters can be found in 5 locations in North America.
So what does "functionally extinct" mean?
Oysters no longer play almost any significant role in their ecosystems.
From the AFP:
http://www.huffingtonpost.com/2011/02/04/oysters-are-functionally-_n_818870.html
Dean Praetorius
First Posted: 02/ 4/11 04:21 PM
Oysters aren't disappearing from the dining table anytime soon, but they may be disappearing from our oceans.
A recent study published in BioScience has shown that the mollusks, declared "functionally extinct," are disappearing quickly as 85 percent of their reefs have been destroyed through disease or over-harvesting, according to the AFP. 75 percent of the remaining wild oysters can be found in 5 locations in North America.
So what does "functionally extinct" mean?
Oysters no longer play almost any significant role in their ecosystems.
From the AFP:
"Oyster reefs are at less than 10 percent of their prior abundance in most bays (70 percent) and ecoregions (63 percent)," said the study.
"They are functionally extinct -- in that they lack any significant ecosystem role and remain at less than one percent of prior abundances in many bays (37 percent) and ecoregions (28 percent) -- particularly in North America, Australia and Europe."While the study didn't include parts of South Africa, China, Japan, North Korea, and South Korea, other studies suggest that there's been a significant decrease in oysters in these regions as well, according to the authors.
http://www.huffingtonpost.com/2011/02/04/oysters-are-functionally-_n_818870.html
Tuesday, September 7, 2010
Researchers say 21 pct of freshwater species in northern Africa threatened with extinction
By Associated Press
8:52 a.m. EDT, September 7, 2010
STOCKHOLM (AP) — Researchers at an international water conference in Stockholm said that 21 percent of freshwater species in northern Africa are threatened with extinction.
Scientists from the International Union for Conservation of Nature presented a new report on Tuesday, which shows more than 1,000 fish, crabs, mollusks, aquatic plants and insects in northern Africa are in danger.
The IUCN said agriculture, water abstraction and dams are the biggest threats to these species, and urged governments to better manage their water resources.
The report summarizes the findings of 200 scientists, who had worked for five years to assess a total of 5,167 African freshwater species.
http://www.orlandosentinel.com/news/space/sns-ap-eu-sweden-african-species,0,7467007.story
8:52 a.m. EDT, September 7, 2010
STOCKHOLM (AP) — Researchers at an international water conference in Stockholm said that 21 percent of freshwater species in northern Africa are threatened with extinction.
Scientists from the International Union for Conservation of Nature presented a new report on Tuesday, which shows more than 1,000 fish, crabs, mollusks, aquatic plants and insects in northern Africa are in danger.
The IUCN said agriculture, water abstraction and dams are the biggest threats to these species, and urged governments to better manage their water resources.
The report summarizes the findings of 200 scientists, who had worked for five years to assess a total of 5,167 African freshwater species.
http://www.orlandosentinel.com/news/space/sns-ap-eu-sweden-african-species,0,7467007.story
Researchers say 21 pct of freshwater species in northern Africa threatened with extinction
By Associated Press
8:52 a.m. EDT, September 7, 2010
STOCKHOLM (AP) — Researchers at an international water conference in Stockholm said that 21 percent of freshwater species in northern Africa are threatened with extinction.
Scientists from the International Union for Conservation of Nature presented a new report on Tuesday, which shows more than 1,000 fish, crabs, mollusks, aquatic plants and insects in northern Africa are in danger.
The IUCN said agriculture, water abstraction and dams are the biggest threats to these species, and urged governments to better manage their water resources.
The report summarizes the findings of 200 scientists, who had worked for five years to assess a total of 5,167 African freshwater species.
http://www.orlandosentinel.com/news/space/sns-ap-eu-sweden-african-species,0,7467007.story
8:52 a.m. EDT, September 7, 2010
STOCKHOLM (AP) — Researchers at an international water conference in Stockholm said that 21 percent of freshwater species in northern Africa are threatened with extinction.
Scientists from the International Union for Conservation of Nature presented a new report on Tuesday, which shows more than 1,000 fish, crabs, mollusks, aquatic plants and insects in northern Africa are in danger.
The IUCN said agriculture, water abstraction and dams are the biggest threats to these species, and urged governments to better manage their water resources.
The report summarizes the findings of 200 scientists, who had worked for five years to assess a total of 5,167 African freshwater species.
http://www.orlandosentinel.com/news/space/sns-ap-eu-sweden-african-species,0,7467007.story
Tuesday, August 31, 2010
Scientists find new invasive fresh water clam species in Lake George
RIGHT: Asian clam (Corbicula fluminea)August 30, 2010
Scientists find new invasive fresh water clam species in lake George
(PhysOrg.com) -- The new species (Corbicula fluminea) was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of the Rensselaer Darrin Fresh Water Institute.
The Rensselaer Polytechnic Institute Darrin Fresh Water Institute (DFWI) has discovered a new invasive fresh water clam species in Lake George. This species, found last week by DFWI student Jeremy Farrell, was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of DFWI.
Nierzwicki-Bauer said the species - Corbicula fluminea - is an invasive clam from Asia, capable of self fertilization, achieving densities of thousands per square meter, and crowding native species from their typical habitats. Commonly known as the Asian clam, it is a light brown triangular clam that can survive in fresh and brackish waters. If the invasion is a localized one, it may be possible to eradicate, she added. The dominant native mussel in Lake George is Elliptio complanata.
“It is imperative that we move quickly to determine the extent of this infestation to assess the best treatment options that can be undertaken immediately,” said Nierzwicki-Bauer, who is also a professor of biology at Rensselaer. “We have reached out to the regulatory agencies to assess all our options.”
The Lake George environmental organizations have contracted to bring in an expert in invertebrate biology and scientific SCUBA: Dan Marelli, from Florida. He has worked with DFWI scientists for over 15 years to help coordinate SCUBA surveys, and he will direct new surveys that will be carried out by FUND for Lake George, DFWI, Bateaux Below Inc., and volunteer divers. Immediate plans include a survey of the shallow and embayment areas to establish the extent of infestation. Possible eradication or management strategies include use of a benthic barrier, essentially a plastic mat that could “smother” the clams, suction harvesting, or a combination of these methods. Currently, benthic mats are being used on a one-acre area in Lake Tahoe, Calif., to help manage the infestation there. Preliminary field work by DFWI staff indicates that a minimum of 2.5 acres in Lake George is infested.
The environmental groups will be coordinating with the Adirondack Park Agency and the New York Department of Environmental Conservation.
An initial plan of action has been organized to complete a SCUBA survey during the next two weeks to determine the geographical range of the infestation. This will involve surveys by divers of the lake bottom sediment. Other nearby areas with suitable habitat will be surveyed soon. Initial surveys will be supervised by Marelli. Once the extent of the infestation has been quantified, either a management or eradication strategy will be determined. The initial survey work will utilize the eight-diver crew of Aquatic Invasives Management (AIM) of Lake Placid, which is currently working in Lake George on management of Eurasian watermilfoil, under a contract with the FUND for Lake George.
Peter Bauer, executive director of the FUND for Lake George, said, “This is the newest invader to be found in Lake George. We’ve long had Eurasian watermilfoil and curlyleaf pond weed, as well as zebra mussels. We’ve seen a few plants of Brittle Naiad, too. We don’t know the current extent of the Asian clam infestation, but if we’re lucky maybe this is an isolated infestation in Lake George that we caught early.”
Once field investigations are completed, further information on the extent of the infestation will be provided.
“It is now most important that we pull together with other organizations and the public to mount a rapid and effective response to this disturbing discovery,” said Bruce E. Young, chairman of the Lake George Park Commission. “The community should be reassured that steps are under way to assess the extent of the Asian clam colony and if possible, eradicate it.”
“While the discovery of an established Asian clam population in the lake was not good news to hear, the good news is that all the groups involved are taking swift action and rallying the troops. We are all divvying up the tasks, and LGA is heading up public outreach. It is very important to spread the word to area boaters and business owners, as we do not want the clam to spread further within our own lake or to other nearby bodies of water as well. We will be providing educational materials about the Asian clam and its spread to boaters, businesses, and residents all around the lake in the next few days,” said Walt Lender, executive director, Lake George Association.
“It will take a concerted partnership effort to address Asian clam in Lake George. Key partners have already begun the rapid response process to survey, evaluate, and determine feasible control and spread prevention options. The Lake Champlain Basin Program will assist management efforts in any way possible as this species affects not only Lake George but the entire Lake Champlain Basin watershed and beyond,” said Meg Modley, Aquatic Invasive Species management coordinator, Lake Champlain Basin Program.
Background on Corbicula fluminea
Asian clams (Corbicula fluminea) are native to South East Asia and were first documented on the west coast of the United States in 1938. Since then they have spread to over 40 states. Asian clams are small, averaging less than 25mm (1.5 inches) with an oval triangular shape, deep at the hinge. Its outer shell is yellow brown, light brown to black with distinctive elevated, evenly spaced concentric ridges on the surface.
The Asian clam is a very hardy and persistent freshwater mollusk, capable of rapid growth and spread. The Asian clam prefers to colonize on sandy substrates in quiet, warmer, sunlit waters, and can be found with one-third of its shell protruding above the substrate (although it has been found at water depths to 250 feet and within the sediment buried up to 7 inches in Lake Tahoe). Asian clams can form dense clusters, with up to 5,000 animals per square meter. Asian clams are able to withstand freezing conditions, but their ability to reproduce decreases with exposure to lower temperatures (below 10oC/50oF). For a long time, New England was considered environmentally inhospitable to the Asian clam.
The Asian clam is hermaphroditic and therefore capable of self-fertilization. A single clam can release over 400 offspring per day, depending on the conditions. The microscopic pediveligers (the final veliger or larval stage) travel along the substrate to a new location, attaching with byssus fibers to any available suitable substrate. The young that are hatched in the spring usually attain maturity by the fall (at 6-10 mm) and live an average of two to four years, with a maximum life span of seven years.
Geoffrey Schladow, director of the Tahoe Environmental Research Center of the University of California, Davis, said the Asian clams promote so much algae growth that they can turn some waters from blue to green. As they filter the water and consume plankton, they deposit high concentrations of nutrients in their excretions. Another significant impact of the Asian clams infestations is the “biofouling” or the impairment or degradation of intake pipes for power plants and drinking water treatment systems.
Provided by Rensselaer Polytechnic Institute (news : web)
http://www.physorg.com/news202399687.htmlScientists find new invasive fresh water clam species in Lake George
RIGHT: Asian clam (Corbicula fluminea)August 30, 2010
Scientists find new invasive fresh water clam species in lake George
(PhysOrg.com) -- The new species (Corbicula fluminea) was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of the Rensselaer Darrin Fresh Water Institute.
The Rensselaer Polytechnic Institute Darrin Fresh Water Institute (DFWI) has discovered a new invasive fresh water clam species in Lake George. This species, found last week by DFWI student Jeremy Farrell, was located in the Village of Lake George and poses a serious threat to native mussels and the Lake George ecosystem, according to Sandra Nierzwicki-Bauer, director of DFWI.
Nierzwicki-Bauer said the species - Corbicula fluminea - is an invasive clam from Asia, capable of self fertilization, achieving densities of thousands per square meter, and crowding native species from their typical habitats. Commonly known as the Asian clam, it is a light brown triangular clam that can survive in fresh and brackish waters. If the invasion is a localized one, it may be possible to eradicate, she added. The dominant native mussel in Lake George is Elliptio complanata.
“It is imperative that we move quickly to determine the extent of this infestation to assess the best treatment options that can be undertaken immediately,” said Nierzwicki-Bauer, who is also a professor of biology at Rensselaer. “We have reached out to the regulatory agencies to assess all our options.”
The Lake George environmental organizations have contracted to bring in an expert in invertebrate biology and scientific SCUBA: Dan Marelli, from Florida. He has worked with DFWI scientists for over 15 years to help coordinate SCUBA surveys, and he will direct new surveys that will be carried out by FUND for Lake George, DFWI, Bateaux Below Inc., and volunteer divers. Immediate plans include a survey of the shallow and embayment areas to establish the extent of infestation. Possible eradication or management strategies include use of a benthic barrier, essentially a plastic mat that could “smother” the clams, suction harvesting, or a combination of these methods. Currently, benthic mats are being used on a one-acre area in Lake Tahoe, Calif., to help manage the infestation there. Preliminary field work by DFWI staff indicates that a minimum of 2.5 acres in Lake George is infested.
The environmental groups will be coordinating with the Adirondack Park Agency and the New York Department of Environmental Conservation.
An initial plan of action has been organized to complete a SCUBA survey during the next two weeks to determine the geographical range of the infestation. This will involve surveys by divers of the lake bottom sediment. Other nearby areas with suitable habitat will be surveyed soon. Initial surveys will be supervised by Marelli. Once the extent of the infestation has been quantified, either a management or eradication strategy will be determined. The initial survey work will utilize the eight-diver crew of Aquatic Invasives Management (AIM) of Lake Placid, which is currently working in Lake George on management of Eurasian watermilfoil, under a contract with the FUND for Lake George.
Peter Bauer, executive director of the FUND for Lake George, said, “This is the newest invader to be found in Lake George. We’ve long had Eurasian watermilfoil and curlyleaf pond weed, as well as zebra mussels. We’ve seen a few plants of Brittle Naiad, too. We don’t know the current extent of the Asian clam infestation, but if we’re lucky maybe this is an isolated infestation in Lake George that we caught early.”
Once field investigations are completed, further information on the extent of the infestation will be provided.
“It is now most important that we pull together with other organizations and the public to mount a rapid and effective response to this disturbing discovery,” said Bruce E. Young, chairman of the Lake George Park Commission. “The community should be reassured that steps are under way to assess the extent of the Asian clam colony and if possible, eradicate it.”
“While the discovery of an established Asian clam population in the lake was not good news to hear, the good news is that all the groups involved are taking swift action and rallying the troops. We are all divvying up the tasks, and LGA is heading up public outreach. It is very important to spread the word to area boaters and business owners, as we do not want the clam to spread further within our own lake or to other nearby bodies of water as well. We will be providing educational materials about the Asian clam and its spread to boaters, businesses, and residents all around the lake in the next few days,” said Walt Lender, executive director, Lake George Association.
“It will take a concerted partnership effort to address Asian clam in Lake George. Key partners have already begun the rapid response process to survey, evaluate, and determine feasible control and spread prevention options. The Lake Champlain Basin Program will assist management efforts in any way possible as this species affects not only Lake George but the entire Lake Champlain Basin watershed and beyond,” said Meg Modley, Aquatic Invasive Species management coordinator, Lake Champlain Basin Program.
Background on Corbicula fluminea
Asian clams (Corbicula fluminea) are native to South East Asia and were first documented on the west coast of the United States in 1938. Since then they have spread to over 40 states. Asian clams are small, averaging less than 25mm (1.5 inches) with an oval triangular shape, deep at the hinge. Its outer shell is yellow brown, light brown to black with distinctive elevated, evenly spaced concentric ridges on the surface.
The Asian clam is a very hardy and persistent freshwater mollusk, capable of rapid growth and spread. The Asian clam prefers to colonize on sandy substrates in quiet, warmer, sunlit waters, and can be found with one-third of its shell protruding above the substrate (although it has been found at water depths to 250 feet and within the sediment buried up to 7 inches in Lake Tahoe). Asian clams can form dense clusters, with up to 5,000 animals per square meter. Asian clams are able to withstand freezing conditions, but their ability to reproduce decreases with exposure to lower temperatures (below 10oC/50oF). For a long time, New England was considered environmentally inhospitable to the Asian clam.
The Asian clam is hermaphroditic and therefore capable of self-fertilization. A single clam can release over 400 offspring per day, depending on the conditions. The microscopic pediveligers (the final veliger or larval stage) travel along the substrate to a new location, attaching with byssus fibers to any available suitable substrate. The young that are hatched in the spring usually attain maturity by the fall (at 6-10 mm) and live an average of two to four years, with a maximum life span of seven years.
Geoffrey Schladow, director of the Tahoe Environmental Research Center of the University of California, Davis, said the Asian clams promote so much algae growth that they can turn some waters from blue to green. As they filter the water and consume plankton, they deposit high concentrations of nutrients in their excretions. Another significant impact of the Asian clams infestations is the “biofouling” or the impairment or degradation of intake pipes for power plants and drinking water treatment systems.
Provided by Rensselaer Polytechnic Institute (news : web)
http://www.physorg.com/news202399687.htmlWednesday, June 2, 2010
Snails on crystal meth: The facts
Profs spend days poking hopped-up molluscs with sticks
By Lewis Page
Posted in Biology, 28th May 2010 14:27 GMT
In a development whose importance it would be difficult to exaggerate, scientists have produced research answering one of the great questions facing humanity in the 21st century: what happens if you get snails hopped up on crystal meth and poke them with sticks?
The drug-pushing scientists in question are Barbara Sorg of Washington State Uni and Ken Lukowiak of the University of Calgary. The mollusc they chose for their experiments was the pond snail Lymnaea stagnalis.
The two snail savants placed their slimy drug-slaves into pond water which they had spiked with methamphetamine, described as "a highly addictive drug that seduces victims by increasing self-esteem and sexual pleasure, and inducing euphoria".
Having got their slippery subjects well addled on this delightful but damaging chemical treat, Sorg and Lukowiak then tested their memories by means of varying the amount of oxygen in the pondwater and poking them with sticks.
Perhaps we should explain. Low oxygen levels often occur in normal outdoor ponds not laced with illegal narcotics, and in this case the local L stagnalis will extend their "pneumostomes" (breathing tubes) above the surface to get more life-giving oxy.
However, it is possible to train them not to do this by sitting next to the pond or lab tank and poking any suffocating snail which dares to wave its squelchy snorkels. This is actually a standard, widely-used method among biologists for testing snails' intellectual powers.
After a lengthy and painstaking period of sitting in the lab poking snails immersed in various different mixtures of pondwater and drugs, Lukowiak and Sorg report that in fact methamphetamine makes snails' memories much better. According to a statement issued on their behalf:
http://www.theregister.co.uk/2010/05/28/snails_on_crystal_meth/
By Lewis Page
Posted in Biology, 28th May 2010 14:27 GMT
In a development whose importance it would be difficult to exaggerate, scientists have produced research answering one of the great questions facing humanity in the 21st century: what happens if you get snails hopped up on crystal meth and poke them with sticks?
The drug-pushing scientists in question are Barbara Sorg of Washington State Uni and Ken Lukowiak of the University of Calgary. The mollusc they chose for their experiments was the pond snail Lymnaea stagnalis.
The two snail savants placed their slimy drug-slaves into pond water which they had spiked with methamphetamine, described as "a highly addictive drug that seduces victims by increasing self-esteem and sexual pleasure, and inducing euphoria".
Having got their slippery subjects well addled on this delightful but damaging chemical treat, Sorg and Lukowiak then tested their memories by means of varying the amount of oxygen in the pondwater and poking them with sticks.
Perhaps we should explain. Low oxygen levels often occur in normal outdoor ponds not laced with illegal narcotics, and in this case the local L stagnalis will extend their "pneumostomes" (breathing tubes) above the surface to get more life-giving oxy.
However, it is possible to train them not to do this by sitting next to the pond or lab tank and poking any suffocating snail which dares to wave its squelchy snorkels. This is actually a standard, widely-used method among biologists for testing snails' intellectual powers.
After a lengthy and painstaking period of sitting in the lab poking snails immersed in various different mixtures of pondwater and drugs, Lukowiak and Sorg report that in fact methamphetamine makes snails' memories much better. According to a statement issued on their behalf:
Memories formed under the influence of meth seem to be harder to forget, possibly because the drug disrupts the mechanisms for forgetting, and could help us to understand how amphetamines enhance memory in humans.The research is to be published in the Journal of Experimental Biology. Sorg and Lukowiak have previously carried out similar studies involving snails on cocaine. ®
http://www.theregister.co.uk/2010/05/28/snails_on_crystal_meth/
Tuesday, March 16, 2010
Florida on guard against giant snails
PHOTO: J.M.GargEfforts are underway to prevent the reestablishment of African mollusks, which threaten crops and public health.
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March 14, 2010 By Anthony Colarossi
Reporting from Orlando, Fla. — They're not as menacing as Burmese pythons proliferating in the Everglades, but giant African snails are targets of the government too.
The invasive mollusks are considered a major plant pest and a potential public health threat because they can spread diseases, including meningitis. Now federal and state authorities are seeking to prevent the large, slimy, shell-toting snails from reestablishing themselves in Florida.
Once established, agricultural officials said, the mollusks "can create a giant swath of destruction."
"The idea is that these are prolific breeders," said Mark Fagan, spokesman for the Florida Department of Agriculture and Consumer Services. "Our primary concern is the potential harm it can do to agricultural crops, as well as [public] health concerns."
The Florida department, the U.S. Department of Agriculture and the U.S. Fish and Wildlife Service are leading the mollusk-prevention effort.
Known as Achatina fulica, the species is one of the world's largest land snails. They can grow to 8 inches long and 4.5 inches in diameter. It is illegal to import the snails into the United States without a permit.
The snail has not been an issue in Florida for several decades. In 1966, a child smuggled three snails into the Miami area as pets. His grandmother later released them into a garden, and by 1973, the population had grown to more than 18,000, officials said.
Over the next decade, officials spent more than $1 million to eradicate them. That effort is considered the only successful giant African snail eradication on record.
Scientists say the snails consume at least 500 kinds of plants, including citrus crops, Fagan said.
They also can damage buildings by consuming plaster, stucco and other materials they need to grow their shells.
They carry parasites and worse. "These snails are known to carry meningitis bacteria, so it's also a health concern," Fagan said.
The snails are identified by seven to nine whorls, or spirals. They have a brownish shell covering half the length of their bodies. They live as long as nine years and have female and male reproductive organs.
After mating, each snail can produce 100 to 400 eggs. Mated adults lay about 1,200 eggs a year.
The snails originate in East Africa. Officials say they have been introduced into Caribbean islands such as Martinique and Guadeloupe, and they have been detected in Saint Lucia and Barbados.
Fagan said multiple snails were found in February at one property in Hialeah, Fla. Authorities searched the nearby area, but no other snails turned up, he said.
Last year, state and federal wildlife officials began a concerted effort to prevent the spread of pythons in and around the Everglades because those invasive reptiles prey on native species.
Fagan said it's difficult to compare the dangers posed by two species. "The snakes pose a completely different threat to nature," he said. "I don't think you can compare the two."
http://articles.latimes.com/2010/mar/14/nation/la-na-giant-snails14-2010mar14
(Submitted by D.R. Shoop)
Friday, January 29, 2010
Sex and the Single Snail
Study shows benefits of sexual reproduction over asexual.
By Fariss Samarrai
28 January 2010
Why have sex?
That is one of the big questions in evolutionary biology.
Sexual reproduction is a high-energy endeavor, requiring, often, the quest for a mate, the actual act of sex, and the carrying of offspring (almost always by the females).
Why not reproduce asexually? Many organisms do, though most of them are single-celled bacteria and other simple life forms. Still, some multicellular organisms also reproduce asexually, including many plants, insects, some reptiles, various mollusks and a few fishes.
This highly efficient mode of reproduction is a low-energy endeavor, requiring no search for a mate, no sexual act, and sometimes, no carrying of offspring. It also allows rapid and abundant proliferation, since all members of that population are female and able to produce offspring.
So, yes, why have sex?
The prevailing theory is that sexual reproduction, which requires two genders, allows genetic intermingling that overall is very good for both the individuals and the species as a whole.
Asexual reproduction, on the other hand, is largely static, where each offspring is genetically identical to every other. This allows for the ongoing accumulation and replication of harmful mutations and little room for adaptation to rapidly changing environments, such as the introduction or quick proliferation of a pathogen. This could, in the long run, lead to extinction of the species.
A new study, by researchers at the University of Virginia and the University of Iowa, published currently in the journal Molecular Biology and Evolution, provides additional credence to this understanding.
“We demonstrated that sexual reproduction allows organisms to clean deleterious mutations from their genome,” said U.Va. biology professor Doug Taylor, who co-authored the study. “Asexual reproduction does indeed allow for the accumulation of deleterious mutations.”
Taylor and his colleagues at Iowa sequenced the entire mitochondrial DNA of multiple sexual and asexual lineages of a species of snail, Potamopyrgus antipodarum, which has sexual and asexual individuals living side-by-side in lakes in New Zealand.
They found that the sexually reproducing variety accumulates harmful mutations in DNA at about half the rate of the asexual lineage. This does not mean that mutations occur at a slower rate, but that, when mutations do occur, they are cleaned from the genome twice as fast in the sexual lineage.
“Asexual lineages suffer from the fact that they can’t clean the mutations from the genome—that’s the theory,” Taylor said. “And we found that, indeed, the sexual lineages are able to purge the genome of their deleterious mutations much more effectively than the asexual lineages.”
Taylor said the finding might be a profound demonstration, at the genetic level, for why sexual reproduction exists in the first place.
Taylor and his colleagues looked for mutations in the snails’ mitochondrial genome, in part because the mitochondrial genome is small and evolves rapidly in most animals. However, the mitochondrial genome is also where many mutations are known to affect the overall health of the full organism.
Underlying genetic disorders in the mitochondria are believed to cause many diseases affecting organisms, such as—in humans—Parkinson’s disease, premature aging, optic neuropathies and muscular degenerative disorders.
http://news.clas.virginia.edu/x16422.xml
(Submitted by T. Peter Park)
By Fariss Samarrai
28 January 2010
Why have sex?
That is one of the big questions in evolutionary biology.
Sexual reproduction is a high-energy endeavor, requiring, often, the quest for a mate, the actual act of sex, and the carrying of offspring (almost always by the females).
Why not reproduce asexually? Many organisms do, though most of them are single-celled bacteria and other simple life forms. Still, some multicellular organisms also reproduce asexually, including many plants, insects, some reptiles, various mollusks and a few fishes.
This highly efficient mode of reproduction is a low-energy endeavor, requiring no search for a mate, no sexual act, and sometimes, no carrying of offspring. It also allows rapid and abundant proliferation, since all members of that population are female and able to produce offspring.
So, yes, why have sex?
The prevailing theory is that sexual reproduction, which requires two genders, allows genetic intermingling that overall is very good for both the individuals and the species as a whole.
Asexual reproduction, on the other hand, is largely static, where each offspring is genetically identical to every other. This allows for the ongoing accumulation and replication of harmful mutations and little room for adaptation to rapidly changing environments, such as the introduction or quick proliferation of a pathogen. This could, in the long run, lead to extinction of the species.
A new study, by researchers at the University of Virginia and the University of Iowa, published currently in the journal Molecular Biology and Evolution, provides additional credence to this understanding.
“We demonstrated that sexual reproduction allows organisms to clean deleterious mutations from their genome,” said U.Va. biology professor Doug Taylor, who co-authored the study. “Asexual reproduction does indeed allow for the accumulation of deleterious mutations.”
Taylor and his colleagues at Iowa sequenced the entire mitochondrial DNA of multiple sexual and asexual lineages of a species of snail, Potamopyrgus antipodarum, which has sexual and asexual individuals living side-by-side in lakes in New Zealand.
They found that the sexually reproducing variety accumulates harmful mutations in DNA at about half the rate of the asexual lineage. This does not mean that mutations occur at a slower rate, but that, when mutations do occur, they are cleaned from the genome twice as fast in the sexual lineage.
“Asexual lineages suffer from the fact that they can’t clean the mutations from the genome—that’s the theory,” Taylor said. “And we found that, indeed, the sexual lineages are able to purge the genome of their deleterious mutations much more effectively than the asexual lineages.”
Taylor said the finding might be a profound demonstration, at the genetic level, for why sexual reproduction exists in the first place.
Taylor and his colleagues looked for mutations in the snails’ mitochondrial genome, in part because the mitochondrial genome is small and evolves rapidly in most animals. However, the mitochondrial genome is also where many mutations are known to affect the overall health of the full organism.
Underlying genetic disorders in the mitochondria are believed to cause many diseases affecting organisms, such as—in humans—Parkinson’s disease, premature aging, optic neuropathies and muscular degenerative disorders.
http://news.clas.virginia.edu/x16422.xml
(Submitted by T. Peter Park)
Tuesday, April 7, 2009
Sea mollusks taste their memories to build shells
By Robert Sanders, Media Relations | 01 April 2009
BERKELEY — University of California, Berkeley, graduate student Alistair Boettiger has amassed a beautiful collection of seashells, but not by combing the beach. He created them in his computer.
He and George Oster, a UC Berkeley biophysicist, along with University of Pittsburgh mathematical neuroscientist Bard Ermentrout, have written a computer program that generates the complex patterns of seashells using simple principles developed to explain how the brain works and how memories are stored.
The "neural net" model explains how mollusks build their seashells based on the finding that the mollusk's tongue-like mantle, which overlaps the edge of the growing shell, senses or "tastes" the calcium carbonate layer laid down the day before in order to generate a new layer.
"The pattern on a seashell is the mollusk's memories," said Oster, a professor of environmental science, policy and management and of molecular and cell biology. "The shell is laid down in layers, so the mantle is sensing the history of the mollusk's 'thoughts' and extrapolating to the next layer, just like our brains project into the future."
The studies may help neuroscientists understand how neural networks work in the brain and throughout the body, where neural nets cover our skin and all internal organs.
Full article and photos at: http://www.berkeley.edu/news/media/releases/2009/04/01_seashells.shtml
BERKELEY — University of California, Berkeley, graduate student Alistair Boettiger has amassed a beautiful collection of seashells, but not by combing the beach. He created them in his computer.
He and George Oster, a UC Berkeley biophysicist, along with University of Pittsburgh mathematical neuroscientist Bard Ermentrout, have written a computer program that generates the complex patterns of seashells using simple principles developed to explain how the brain works and how memories are stored.
The "neural net" model explains how mollusks build their seashells based on the finding that the mollusk's tongue-like mantle, which overlaps the edge of the growing shell, senses or "tastes" the calcium carbonate layer laid down the day before in order to generate a new layer.
"The pattern on a seashell is the mollusk's memories," said Oster, a professor of environmental science, policy and management and of molecular and cell biology. "The shell is laid down in layers, so the mantle is sensing the history of the mollusk's 'thoughts' and extrapolating to the next layer, just like our brains project into the future."
The studies may help neuroscientists understand how neural networks work in the brain and throughout the body, where neural nets cover our skin and all internal organs.
Full article and photos at: http://www.berkeley.edu/news/media/releases/2009/04/01_seashells.shtml
Tuesday, March 3, 2009
Underwater Britain: the invasive species
The UK has a rich diversity of marine wildlife and is home to more than 44,000 species from basking sharks to jellyfish and tiny corals.
But that diversity is being threatened. New species are arriving in UK waters every year via container ships, accidental release or commercial fishing.
Most live in harmony with the pre-existing wildlife but some ‘invasive aliens’, as marine scientists refer to them, are disrupting native species and their habitats. Species like the zebra mussel and Chinese mitten crab have no native predators or competitors, and as a result, their populations can quickly multiply.
For full article and photos see: http://environment.uk.msn.com/wildlife/gallery.aspx?cp-documentid=14280445
But that diversity is being threatened. New species are arriving in UK waters every year via container ships, accidental release or commercial fishing.
Most live in harmony with the pre-existing wildlife but some ‘invasive aliens’, as marine scientists refer to them, are disrupting native species and their habitats. Species like the zebra mussel and Chinese mitten crab have no native predators or competitors, and as a result, their populations can quickly multiply.
For full article and photos see: http://environment.uk.msn.com/wildlife/gallery.aspx?cp-documentid=14280445
Thursday, February 19, 2009
Lake Michigan fish populations threatened by decline of tiny creature
Public release date: 19-Feb-2009
Contact: Davina Quarterman
dquarterman@wiley.com
Wiley-Blackwell
The quick decline of a tiny shrimp-like species, known scientifically as Diporeia, is related to the aggressive population growth of non-native quagga mussels in the Great Lakes, say NOAA scientists. As invasive mussel numbers increase, food sources for Diporeia and many aquatic species have steadily and unilaterally declined.
A recent research study from NOAA's Great Lakes Environmental Laboratory published this week in Freshwater Biology documents the recent decline of Diporeia and the explosive growth of quagga mussels in Lake Michigan. Over the past five years quagga mussels have displaced native Diporeia as the dominant bottom dwelling organism, leading to a major disruption in the lake's food web.
"Quagga mussels have displaced other more energy-rich food sources and leave fish and other aquatic species with fewer food options," said Tom Nalepa, NOAA research biologist. "The invasive mussels are low in calories and their shell has no nutritional value. Fish feeding on quagga mussels expend considerable energy crushing and passing the indigestible shell."
Scientists at the NOAA Great Lakes lab project that impacts on fish populations will continue and become more pronounced as quagga mussels further spread to all depths occupied by the dwindling Diporeia. It is estimated that the mass of quagga mussels in the lake is now about four times the mass of all prey fish.
In Lake Michigan, declines in Diporeia masses were first observed in the early 1990s soon after the discovery of invasive mussels in the Great Lakes. By 2005, lake populations of the tiny shrimp decreased 96 percent in the 10-year period of the study, with further observations indicating recovery of Diporeia improbable once it has disappeared.
Contact: Davina Quarterman
dquarterman@wiley.com
Wiley-Blackwell
The quick decline of a tiny shrimp-like species, known scientifically as Diporeia, is related to the aggressive population growth of non-native quagga mussels in the Great Lakes, say NOAA scientists. As invasive mussel numbers increase, food sources for Diporeia and many aquatic species have steadily and unilaterally declined.
A recent research study from NOAA's Great Lakes Environmental Laboratory published this week in Freshwater Biology documents the recent decline of Diporeia and the explosive growth of quagga mussels in Lake Michigan. Over the past five years quagga mussels have displaced native Diporeia as the dominant bottom dwelling organism, leading to a major disruption in the lake's food web.
"Quagga mussels have displaced other more energy-rich food sources and leave fish and other aquatic species with fewer food options," said Tom Nalepa, NOAA research biologist. "The invasive mussels are low in calories and their shell has no nutritional value. Fish feeding on quagga mussels expend considerable energy crushing and passing the indigestible shell."
Scientists at the NOAA Great Lakes lab project that impacts on fish populations will continue and become more pronounced as quagga mussels further spread to all depths occupied by the dwindling Diporeia. It is estimated that the mass of quagga mussels in the lake is now about four times the mass of all prey fish.
In Lake Michigan, declines in Diporeia masses were first observed in the early 1990s soon after the discovery of invasive mussels in the Great Lakes. By 2005, lake populations of the tiny shrimp decreased 96 percent in the 10-year period of the study, with further observations indicating recovery of Diporeia improbable once it has disappeared.
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