Didymosphenia geminata
Encyclopedia
Didymosphenia geminata, commonly known as didymo or rock snot, is a species of diatom
that grows in warm and shallow water
. If it overgrows, it can form large mats on the bottom of lake
s, rivers and streams. It is not considered a significant human health risk, but it can affect stream habitats and sources of food for fish and make recreational activities unpleasant. It is considered a nuisance organism or invasive species
. The microscopic alga
can be spread in a single drop of water.
Didymosphenia geminata is a diatom, which is a type of single-celled algae unique for their silica (SiO2) cell walls. The life history of diatoms includes both vegetative and sexual reproduction, though the sexual stage is not yet documented in this species. Although it is symmetric only along the apical axis, typical of gomphonemoid diatoms, it is a cymbelloid, which are typically symmetric along both primary axes. Cells contain a raphe, which allows them to move on surfaces, and an apical porefield, through which a mucopolysaccharide stalk is secreted.
The stalk can attach to rocks, plants, or other submerged surfaces. When the diatom cell divides, through vegetative reproduction, the stalk divides too, eventually forming a mass of branching stalks. The nuisance build-up is not the cell itself, but their massive production of extracellular stalks. Extracellular polymeric substances (EPS) that form the stalks are made primarily of polysaccharides and protein, forming complex, multi-layered structures that are resistant to degradation.
Alberta
: Earliest anecdotal reports of Didymosphenia geminata blooms in Alberta rivers occurred as early as the mid-1990s (e.g. the upper Bow River
in Banff National Park
). Reports of Didymo presence and bloom formation have been documented for most rivers in the South Saskatchewan River
Basin in recent years (2005 to current).
British Columbia
: Didymosphenia geminata was first reported as a nuisance species in the late 1980s on Vancouver Island
. Since that time, outbreaks of Didymo have been reported on the island and on the mainland.
: Didymo was found in the Cumberland River below Wolf Creek Dam in the Crocus Creek area 2008. The State of Kentucky has banned felt-soled waders in the river to prevent spread of the organism.
Maryland
: In May 2008, didymo was found in the Gunpowder River
in Baltimore County
. In December 2009, it was found in the Savage River
in western Maryland.
New Hampshire
: During the summer of 2007, didymo was discovered for the first time in New Hampshire in the Connecticut River
near Pittsburg
.
New York
: In August 2007, didymo was first discovered in New York State in a section of the Batten Kill
, a Hudson River
tributary, in Washington County
. It has also been found in Esopus Creek
in the Catskills
.
South Dakota
: Didymo has been present in Rapid Creek
in South Dakota
since at least 2005, and is blamed for a significant decline in the brown trout population there. It is also present to lesser extents in other nearby locations.
Tennessee
: Didymo was found in the tailwaters of the Norris
, Cherokee
, Wilbur
and South Holston
hydroelectric dams in 2005, the first U.S. finding east of the Mississippi River
.
Vermont
: In June 2007, didymo was discovered in the Connecticut River
near Bloomfield, Vermont
, its first recorded discovery in the northeastern United States
. The sighting was reported by a fishing guide and confirmed by Dr. Sarah Spaulding, a didymo expert from Denver, Colorado
.
Virginia
: Didymo was identified in western Virginia in the summer of 2006 in the Smith River
, the Jackson River
, and the Pound River
.
West Virginia
: In 2008, didymo was found in West Virginia in the Elk River
in Webster County near Webster Springs
and in Glady Fork and Gandy Creek, both in Randolph County
. The alga was found in Seneca Creek
in Pendleton County
in 2009.
: In 2010, the United States Geological Survey (USGS)
and a Chilean laboratory, Centro de Investigacion en Ecosistemas de la Patagonia (CIEP), confirmed the identification of the diatom Didymosphenia geminata (didymo) as forming extensive blooms in Chilean rivers in Chile's Los Lagos Region (X Región de Los Lagos)
in the Andes
west of Esquel
, a town in the Chubut Province
of Argentina, with reports from the Espolon River and the Futaleufú River
for a total of more than 56 river kilometers affected.
in 2004, the first time it was found in the southern hemisphere. To restrict its spread, the whole of New Zealand's South Island was declared a controlled area in December 2005. Extensive publicity was carried out to limit the spread, but it has subsequently been found in an increasing number of rivers there.
The following methods have been recommended to prevent the spread of didymo in New Zealand:
Check: Before leaving the river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the site. If you find clumps later don't wash them down the drain, treat them with the approved methods below, dry them and soak them in bleach for at least 4 hours.
Clean: Soak and scrub all items for at least one minute in either hot (60°C) water, a 2% solution of household bleach, antiseptic hand cleaner, or dishwashing detergent.
Dry: If cleaning is not practical (e.g. livestock, pets), after the item is completely dry wait an additional 48 hours before contact or use in any other waterway.
New Zealand and the U.S. states of Alaska
, Maryland
and Vermont
have banned anglers from wearing felt-soled boots. Orvis
, a leading U.S. manufacturer of fly-fishing equipment, has started selling more rubber-soled boots than felt-soled.
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
that grows in warm and shallow water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. If it overgrows, it can form large mats on the bottom of lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s, rivers and streams. It is not considered a significant human health risk, but it can affect stream habitats and sources of food for fish and make recreational activities unpleasant. It is considered a nuisance organism or invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
. The microscopic alga
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
can be spread in a single drop of water.
Description
The stalk can attach to rocks, plants, or other submerged surfaces. When the diatom cell divides, through vegetative reproduction, the stalk divides too, eventually forming a mass of branching stalks. The nuisance build-up is not the cell itself, but their massive production of extracellular stalks. Extracellular polymeric substances (EPS) that form the stalks are made primarily of polysaccharides and protein, forming complex, multi-layered structures that are resistant to degradation.
Native range
The native distribution of D. geminata is the cool temperate regions of the Northern Hemisphere, including the rivers of northern forests and alpine regions of Europe, Asia and parts of North America. Until its recent discovery in New Zealand, where it was introduced, it was never previously found in the Southern Hemisphere. The distribution of didymo in the last two decades appears to be gradually expanding outside its native range. Even within its native range, there have been reports of excessive growths in areas where it previously existed only in low concentrations.Canada
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
: Earliest anecdotal reports of Didymosphenia geminata blooms in Alberta rivers occurred as early as the mid-1990s (e.g. the upper Bow River
Bow River
The Bow River is a river in the Canadian province of Alberta. It is a tributary of the South Saskatchewan River, and is considered the headwater of the Nelson River....
in Banff National Park
Banff National Park
Banff National Park is Canada's oldest national park, established in 1885 in the Rocky Mountains. The park, located 110–180 kilometres west of Calgary in the province of Alberta, encompasses of mountainous terrain, with numerous glaciers and ice fields, dense coniferous forest, and alpine...
). Reports of Didymo presence and bloom formation have been documented for most rivers in the South Saskatchewan River
South Saskatchewan River
The South Saskatchewan River is a major river in Canada that flows through the provinces of Alberta and Saskatchewan....
Basin in recent years (2005 to current).
British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
: Didymosphenia geminata was first reported as a nuisance species in the late 1980s on Vancouver Island
Vancouver Island
Vancouver Island is a large island in British Columbia, Canada. It is one of several North American locations named after George Vancouver, the British Royal Navy officer who explored the Pacific Northwest coast of North America between 1791 and 1794...
. Since that time, outbreaks of Didymo have been reported on the island and on the mainland.
United States
KentuckyKentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
: Didymo was found in the Cumberland River below Wolf Creek Dam in the Crocus Creek area 2008. The State of Kentucky has banned felt-soled waders in the river to prevent spread of the organism.
Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
: In May 2008, didymo was found in the Gunpowder River
Gunpowder River
The Gunpowder River is a tidal inlet on the western side of Chesapeake Bay in Maryland, United States. It is formed by the joining of two freshwater rivers, Gunpowder Falls and Little Gunpowder Falls.-Gunpowder Falls:The Big Gunpowder, long, begins in the extreme southern part of Pennsylvania's...
in Baltimore County
Baltimore County, Maryland
Baltimore County is a county located in the northern part of the US state of Maryland. In 2010, its population was 805,029. It is part of the Baltimore-Washington Metropolitan Area. Its county seat is Towson. The name of the county was derived from the barony of the Proprietor of the Maryland...
. In December 2009, it was found in the Savage River
Savage River
-In Australia:*Savage River , a tributary of the Pieman River*Savage River, Tasmania, a town in northwestern Tasmania*Savage River National Park, in Tasmania-In the United States:*Savage River , a tributary of the Potomac River...
in western Maryland.
New Hampshire
New Hampshire
New Hampshire is a state in the New England region of the northeastern United States of America. The state was named after the southern English county of Hampshire. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Atlantic Ocean to the east, and the Canadian...
: During the summer of 2007, didymo was discovered for the first time in New Hampshire in the Connecticut River
Connecticut River
The Connecticut River is the largest and longest river in New England, and also an American Heritage River. It flows roughly south, starting from the Fourth Connecticut Lake in New Hampshire. After flowing through the remaining Connecticut Lakes and Lake Francis, it defines the border between the...
near Pittsburg
Pittsburg, New Hampshire
Pittsburg is a town in Coos County, New Hampshire, United States. The population was 869 at the 2010 census. It is the northernmost town in New Hampshire and the largest town by area in the state - and in New England as well - more than twice the size of the next largest town, Lincoln. U.S...
.
New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
: In August 2007, didymo was first discovered in New York State in a section of the Batten Kill
Batten Kill
The Batten Kill, or Battenkill, or the Battenkill River, is a river rising in Vermont that flows into New York and is a tributary of the Hudson River....
, a Hudson River
Hudson River
The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...
tributary, in Washington County
Washington County, New York
Washington County is a county located in the U.S. state of New York. It is part of the Glens Falls, New York, Metropolitan Statistical Area. As of the 2010 census, the population was 63,216. It was named for the Revolutionary War general George Washington...
. It has also been found in Esopus Creek
Esopus Creek
Esopus Creek is a tributary of the Hudson River that drains the east-central Catskill Mountains of the U.S. state of New York. From its source at Winnisook Lake on the slopes of Slide Mountain, the Catskills' highest peak, it flows across Ulster County to the Hudson at Saugerties. Many tributaries...
in the Catskills
Catskill Mountains
The Catskill Mountains, an area in New York State northwest of New York City and southwest of Albany, are a mature dissected plateau, an uplifted region that was subsequently eroded into sharp relief. They are an eastward continuation, and the highest representation, of the Allegheny Plateau...
.
South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
: Didymo has been present in Rapid Creek
Rapid Creek (South Dakota)
Rapid Creek is a tributary of the Cheyenne River, approximately 86 mi long, in South Dakota in the United States.It rises in southwestern South Dakota, in the Black Hills National Forest in the Black Hills in Pennington County. It flows east, is joined by Castle Creek, past Silver City and...
in South Dakota
South Dakota
South Dakota is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over...
since at least 2005, and is blamed for a significant decline in the brown trout population there. It is also present to lesser extents in other nearby locations.
Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
: Didymo was found in the tailwaters of the Norris
Norris Dam
Norris Dam is a hydroelectric and flood control structure located on the Clinch River in Anderson County and Campbell County, Tennessee, USA. Its construction in the mid-1930s was the first major project for the Tennessee Valley Authority, which had been created in 1933 to bring economic...
, Cherokee
Cherokee Dam
Cherokee Dam is a hydroelectric dam located on the Holston River in Grainger County and Jefferson County, Tennessee, in the southeastern United States. The dam is operated and maintained by the Tennessee Valley Authority, which built the dam in the early 1940s to help meet urgent demands for...
, Wilbur
Wilbur Dam
Wilbur Dam is a hydroelectric dam on the Watauga River in Carter County, in the U.S. state of Tennessee. It is one of two dams on the river owned and operated by the Tennessee Valley Authority. The dam impounds Wilbur Lake, which extends for about up the Watauga to the base of Watauga Dam...
and South Holston
South Holston Dam
South Holston Dam is a hydroelectric and flood control dam on the South Fork Holston River in Sullivan County, in the U.S. state of Tennessee. It is the uppermost of three dams on the South Fork Holston owned and operated by the Tennessee Valley Authority, which built the dam in the 1940s as part...
hydroelectric dams in 2005, the first U.S. finding east of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
.
Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
: In June 2007, didymo was discovered in the Connecticut River
Connecticut River
The Connecticut River is the largest and longest river in New England, and also an American Heritage River. It flows roughly south, starting from the Fourth Connecticut Lake in New Hampshire. After flowing through the remaining Connecticut Lakes and Lake Francis, it defines the border between the...
near Bloomfield, Vermont
Bloomfield, Vermont
Bloomfield is a town in Essex County, Vermont, United States. The population was 261 as of the 2000 census. It is part of the Berlin, NH–VT Micropolitan Statistical Area...
, its first recorded discovery in the northeastern United States
Northeastern United States
The Northeastern United States is a region of the United States as defined by the United States Census Bureau.-Composition:The region comprises nine states: the New England states of Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont; and the Mid-Atlantic states of New...
. The sighting was reported by a fishing guide and confirmed by Dr. Sarah Spaulding, a didymo expert from Denver, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
.
Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
: Didymo was identified in western Virginia in the summer of 2006 in the Smith River
Smith River (Virginia)
The Smith River is a river in the U.S. states of Virginia and North Carolina. It is a tributary of the Dan River, which it joins at Eden, North Carolina...
, the Jackson River
Jackson River (Virginia)
The Jackson River is a major tributary of the James River in the U.S. state of Virginia, flowing . The James River is formed by the confluence of the Jackson River and the Cowpasture River.-Course:...
, and the Pound River
Pound River
Category: Rivers of Virginia Running through Part of Wise County Virginia, and through Dickenson County Virginia, The Pound River is a tributary of the Russell Fork in the U.S. state of Virginia. Via the Russell Fork, the Levisa Fork, the Big Sandy River, and the Ohio River, it is part of the...
.
West Virginia
West Virginia
West Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
: In 2008, didymo was found in West Virginia in the Elk River
Elk River (West Virginia)
The Elk River is a tributary of the Kanawha River, long, in central West Virginia in the United States. Via the Kanawha and Ohio Rivers, it is part of the watershed of the Mississippi River.-Course:...
in Webster County near Webster Springs
Webster Springs, West Virginia
Webster Springs is a town in Webster County, West Virginia, United States. Although it was incorporated as Addison in 1892, it is more frequently referred to as Webster Springs, the name of the town's post office. It was named as such for Addison McLaughlin, upon whose land the town was originally...
and in Glady Fork and Gandy Creek, both in Randolph County
Randolph County, West Virginia
As of the census of 2000, there were 28,262 people, 11,072 households, and 7,661 families residing in the county. The population density was 27 people per square mile . There were 13,478 housing units at an average density of 13 per square mile...
. The alga was found in Seneca Creek
Seneca Creek (North Fork South Branch Potomac River)
Seneca Creek is a tributary of the North Fork of the South Branch of the Potomac River located entirely within Pendleton County, West Virginia, USA....
in Pendleton County
Pendleton County, West Virginia
As of the census of 2000, there were 8,196 people, 3,350 households, and 2,355 families residing in the county. The population density was 12 people per square mile . There were 5,102 housing units at an average density of 7 per square mile...
in 2009.
South America
ChileChile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
: In 2010, the United States Geological Survey (USGS)
United States Geological Survey
The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...
and a Chilean laboratory, Centro de Investigacion en Ecosistemas de la Patagonia (CIEP), confirmed the identification of the diatom Didymosphenia geminata (didymo) as forming extensive blooms in Chilean rivers in Chile's Los Lagos Region (X Región de Los Lagos)
Los Lagos Region
Los Lagos Region is one of Chile's 15 regions, which are first order administrative divisions, and comprises four provinces: Chiloé, Llanquihue, Osorno and Palena. The region contains the country's second largest island, Chiloé, and the second largest lake, Llanquihue.Its capital is Puerto Montt;...
in the Andes
Andes
The Andes is the world's longest continental mountain range. It is a continual range of highlands along the western coast of South America. This range is about long, about to wide , and of an average height of about .Along its length, the Andes is split into several ranges, which are separated...
west of Esquel
Esquel
According to the , the Esquel district had about 28,000 inhabitants, with one of the highest rates of growth in the province, mainly as result of the immigration of people from Buenos Aires, but also from other provinces. It has wide cement streets with sidewalks, and is clean and well maintained...
, a town in the Chubut Province
Chubut Province
Chubut a province in the southern part of Argentina situated between the 42nd parallel south and the 46th parallel south , the Andes range separating Argentina from Chile, and the Atlantic ocean...
of Argentina, with reports from the Espolon River and the Futaleufú River
Futaleufú River
The Futaleufú River is a river fed by the lakes in the Los Alerces National Park in Chubut Province, Argentina, crossing the Andes Mountains and the international border into Chile and opening into the Yelcho Lake....
for a total of more than 56 river kilometers affected.
New Zealand
Didymosphenia geminata was discovered in New ZealandNew Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
in 2004, the first time it was found in the southern hemisphere. To restrict its spread, the whole of New Zealand's South Island was declared a controlled area in December 2005. Extensive publicity was carried out to limit the spread, but it has subsequently been found in an increasing number of rivers there.
Preventing further spread
Check: Before leaving the river, remove all obvious clumps of algae and look for hidden clumps. Leave them at the site. If you find clumps later don't wash them down the drain, treat them with the approved methods below, dry them and soak them in bleach for at least 4 hours.
Clean: Soak and scrub all items for at least one minute in either hot (60°C) water, a 2% solution of household bleach, antiseptic hand cleaner, or dishwashing detergent.
Dry: If cleaning is not practical (e.g. livestock, pets), after the item is completely dry wait an additional 48 hours before contact or use in any other waterway.
New Zealand and the U.S. states of Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
and Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
have banned anglers from wearing felt-soled boots. Orvis
Orvis
Orvis is a family-owned retail and mail-order business specializing in high-end fly fishing, hunting and sporting goods. Founded in Manchester, Vermont in 1856 by Charles F. Orvis to sell fishing tackle, the company has changed hands only twice and has had only five CEOs in its 150-year history...
, a leading U.S. manufacturer of fly-fishing equipment, has started selling more rubber-soled boots than felt-soled.
External links
- AlgaeBase - taxonomic and nomenclatural information
- CISR: Rock Snot - information on Didymosphenia geminata from the Center for Invasive Species Research
- Species Profile- Didymo (Didymosphenia geminata ), National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for Didymo.