The brook floater (also known as swollen wedgmussel),
''Alasmidonta varicosa'', is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of freshwater mussel, an
aquatic bivalve
Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...
mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...
in the family
Unionidae, the river mussels. It measures 25.1 mm to 80.2 mm in length although other research also suggests it rarely exceeds three inches (75 mm).
Distribution
This species is found in
Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
(New Brunswick and Nova Scotia) and northeastern
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
(
Connecticut
Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York to the west, and Long Island Sound to the south. Its cap ...
,
Georgia,
Maine
Maine () is a state in the New England and Northeastern regions of the United States. It borders New Hampshire to the west, the Gulf of Maine to the southeast, and the Canadian provinces of New Brunswick and Quebec to the northeast and north ...
,
Maryland
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
,
,
New Hampshire
New Hampshire is a U.S. state, state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
,
New Jersey
New Jersey is a state in the Mid-Atlantic and Northeastern regions of the United States. It is bordered on the north and east by the state of New York; on the east, southeast, and south by the Atlantic Ocean; on the west by the Delaware ...
,
New York
New York most commonly refers to:
* New York City, the most populous city in the United States, located in the state of New York
* New York (state), a state in the northeastern United States
New York may also refer to:
Film and television
* '' ...
,
North Carolina
North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
,
Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
,
South Carolina
)''Animis opibusque parati'' ( for, , Latin, Prepared in mind and resources, links=no)
, anthem = " Carolina";" South Carolina On My Mind"
, Former = Province of South Carolina
, seat = Columbia
, LargestCity = Charleston
, LargestMetro = ...
,
Vermont
Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...
,
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth ar ...
and
West Virginia
West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the Bur ...
); It was formerly found in
Rhode Island
Rhode Island (, like ''road'') is a U.S. state, state in the New England region of the Northeastern United States. It is the List of U.S. states by area, smallest U.S. state by area and the List of states and territories of the United States ...
and four watersheds in Massachusetts but are now extinct in Rhode Island and almost extinct in Massachusetts.
1897 Research by
Arnold Edward Ortmann
Arnold Edward Ortmann (April 8, 1863 – January 3, 1927) was a Prussian-born United States naturalist and zoologist who specialized in malacology.
Biography
Ortmann was born in Magdeburg, Prussia on April 8, 1863. A student of Ernst Haeckel, ...
showed it to be common in the
Delaware
Delaware ( ) is a state in the Mid-Atlantic region of the United States, bordering Maryland to its south and west; Pennsylvania to its north; and New Jersey and the Atlantic Ocean to its east. The state takes its name from the adjacent Del ...
and
Susquehanna Rivers.
Habitat and behavior
This mussel lives in high relief streams, under boulders and in sand. Research has shown that it is highly sensitive to increased thermal temperature. It associates with
longnose and
eastern blacknose dace,
golden shiner,
pumpkinseed,
slimy sculpin and
yellow perch
The yellow perch (''Perca flavescens''), commonly referred to as perch, striped perch, American perch, American river perch or preacher is a freshwater perciform fish native to much of North America. The yellow perch was described in 1814 by Samu ...
.
Survival threats and conservation
The brook floater is sensitive to habitat loss for development, dams and road crossings, pollution, summer droughts, trampling, sedimentation, flow alteration, and low oxygen conditions. Hybridization with
elktoe (''Alasmidonta marginata''), a longtime ally, has also shown to be a threat. Research has also shown the population is highly fragmented, low in density, prone to mortality due to old age and there are also low chances of longevity and viable reproduction.
Trematoda
Trematoda is a Class (biology), class of flatworms known as flukes. They are obligate parasite, obligate internal Parasitism, parasites with a complex biological life cycle, life cycle requiring at least two Host_(biology), hosts. The intermedia ...
''rhopalocercous cercaria'' is a parasite of the brook floater. Current research shows population that were largely and widespread known declined by 50% to 95% to almost extinct.
While the IUCN lists it as Vulnerable, the states of New Jersey, Virginia, Massachusetts and New Hampshire
all list it as Endangered, Threatened in Vermont, Maine and New York, Rare/Endangered in Connecticut,
Extinct in Rhode Island and "Species of Special Concern" by the federal government.
References
Alasmidonta
Bivalves described in 1819
Taxonomy articles created by Polbot
{{Unionidae-stub