Winged mapleleaf

Taxobox
name = winged mapleleaf


status = CR | status_system = IUCN2.3
regnum = Animalia
phylum = Mollusca
classis = Bivalvia
ordo = Unionoida
familia = Unionidae
genus = "Quadrula"
species = "Q. fragosa"
binomial = "Quadrula fragosa"
binomial_authority = Conrad, 1835
synonyms =

The wingled mapleleaf ("quadrula fragosa") is an endangered species of mussel found in the United States. It is also known as the false mapleleaf or hickory nut shell.

Description

Quadrula fragosa, also known as the winged mapleleaf, the False mapleleaf, and the Hickory nutshell is a federally endangered mussel that is only located in a few parts of the Midwestern parts of the continental United States. The anterior end of its shell is slightly rounded and the posterior end of the shell is more of a square shape.The shell can range in color from a yellowish-green to light or dark brown. The inside of the shell is white, and there is some iridescent coloring sometimes at one end of the shell. The diameter of a mature mussel is usually about 4 inches (10.2 cm). The shells of these mussels are very thick, and unlike many other mussels there are what appears to be “bumps” running down from the hinge of the shell to the outside edges. It is the patterns of these bumps that help to distinguish the winged mapleleaf from many other mussels that look very similar in appearance to it.

Habitat

The winged mapleleaf at one time could be found in medium to large streams and rivers. The mussel can sometimes be found in the mud, but it is more commonly either found in areas of the river that have gravel or a sandy bottom. The mussel does need to be in moving water in order to survive, the depth of this running water also needs to be somewhere between 0.4 to 2.0 meters. The water also has to be free of pollutants and clean, this is believed to be why the mussel if often more commonly found in areas of sand and the gravel, as these substances are often found in areas where the clarity of cleanliness of the water is at a higher level.

Range

At one time the winged mapleleaf could be found in thirteen states and in nearly all rivers and streams that flow into the Mississippi River. It was once even found in some rivers and streams that flow into the Missouri River. Today however, the mussel can only be found in four rivers in the Midwestern United States, and it is only found in limited areas of these four rivers.

The mussel can be found in a five mile stretch of the St. Croix River, which flows between the states of Minnesota and Wisconsin, In Arkansas it can be found in the Quachita River and also the Saline River, and some populations have been located in the Bourbeuse River in Missouri. Of these 4 locations, the population of these mussels in the short stretch of the St. Croix River is the only one that has been proven to actually be reproducing and growing in population. The mussels in the other 3 locations have no evidence that their populations are growing or that there is actually offspring is being produced. This is a major part of the reason that the species has made its way to the endangered list, if something was to happen to the only reproducing population the species would likely become extinct. It is currently estimated that there is somewhere between 50-1000 individuals that are still alive today.

Feeding

In order for the winged mapleleaf to obtain food the mussel actually siphons in water from the river or stream that it is in and filters out the tiny food particles that are contained in that water. Most of their diet consists mainly of tiny river microorganism, either phytoplankton or zooplankton. These tiny organisms just drift with the river current and are fairly easily siphoned in by the mussel. The young winged mapleleafs attach themselves to the gills of a host fish for feeding and growing purposes until they reach the stage in their life cycle that they can themselves siphon in the water from the river of the stream that they are in.

Reproduction

Reproduction of the winged mapleleaf is very similar to that of many other freshwater mussels. The males release their sperm into the water, then as the females siphon in water the sperm fertilizes the eggs which are located on their gills. After fertilization the eggs develop in to a larva, and once the larva reaches a certain stage it is released from the gills of the mother mussel into the river current. The larva then must reach the gills of a host fish where it can then continue its growing process. The only currently known host fish are the Channel catfish and the Blue catfish.

The larva continue growing on the host fish until they reach their next life cycle stage, and once this stage is reached they are released from the gills of the host fish and find their way to the bottom of the river or stream. Once they have reached the bottom, they then begin maturing into the adult stage of their life cycle. The actual reason for the Channel catfish and the Blue catfish being the only host fish to successfully have a larva mature on them is still unknown. Research was even done by a group of researchers where they used divers to see if they could plant the larva from the mother onto the gills of fish other than the two kinds of catfish. The research was limited from a number of different causes, a limited number of eggs found in the area to transplant on to captive fish, and also the deal of many of the fish that they had captive. The results, however they were very limited, still only showed the Channel and the Blue catfish to be successful host fish for the winged mapleleaf. The oldest known organism in this species is in the St. Croix River and is estimated to be 22 years old, although, the life span of the mussel is actually unknown.

Threats

The winged mapleleaf currently faces a number of different threats to its survival. The invasion of the Zebra mussel (Dreissena polymorpha), which the U.S. Fish and Wildlife Service is taking a number of different steps to try and control is one the biggest threats to the survival of the winged mapleleaf. The Zebra mussel is an extremely invasive species and has the ability to reproduce very quickly, therefore it is taking over the land in which the winged mapleleaf resides and it also uses up food sources that could be used by the other mussels in the area. It was in 2000 that the Zebra mussel began being a problem in the St. Croix River. Sediment accumulation and loss of water quality are also major threats to the population of the mussel.

The reproducing population in the St. Croix River area is near the metropolitan area of St. Paul, and as the larger cities begin to become further developed sediment is dispersed into the river and more and more pollution occurs. The sediment being dispersed into the river also can change the flow of the river, causing erosion and also change in water levels. This is important because the winged mapleleaf needs to be in a fairly pollution free environment and can only survive in certain water levels.

Upstream dam operations also cause changes in the water level, which is another issue that the U.S. Fish and Wildlife Service is trying to take action towards. The biggest issue that the mussel currently faces right now is that there is only one known reproducing population. This means that a severe rainstorm that caused flooding, a pollution spill, or the outbreak of an upstream dam to name of few examples could easily wipe out the entire population and cause it to become extinct.

Extinction Preventions

The winged mapleleaf was added to the list of endangered and threatened plants and animals on July 22, 1991. Being added to this list makes it illegal to collect, harm, threaten, or kill the mussel. Permits can be issued from the U.S. Fish and Wildlife Service to give individuals rights to collect a small portion of the population to conduct research projects, these permits however, are not easily attained. The states of Wisconsin as well as the state of Minnesota are also putting much more effort, along with the help of the U.S. Fish and Wildlife Service to try and control the population and the invasion of the Zebra mussel.There is also currently and experimental population that has been released into the wild. This experimental population was released in parts of the Tennessee River in Colbert and Lauderdale counties. Whether or not these released populations are reproducing has yet to be proven.

Many of the upstream dam operations have also began to be more closely monitored in order to ensure that there is an adequate flow of water in the St. Croix River to provide the necessary amount of water to the river for the winged mapleleaf to survive and reproduce. They are doing this by keeping the flowing levels of the river between the constant 0.4 and 2.0 meter levels that the mussel needs to be in.

ource

* Bogan, A.E. & Seddon, M.B. 1996. [http://www.iucnredlist.org/search/details.php/19040/all Quadrula fragosa] . [http://www.iucnredlist.org 2006 IUCN Red List of Threatened Species. ] Downloaded on 07 August 2007.
* Bauer, Gerhard. Ecology and Evolution of the Freshwater Mussels. 2001. Springer Publishing
* Steingraber,Mark. U.S. fish and wildlife Service. Fort Snelling, MN http://www.fws.gov/midwest/LaCrosseFisheries/projects/mapleleaf.html
* Endangered species facts [electronic resource] : winged mapleleaf Electronic books U.S. Fish and Wildlife Service. [Washington, D.C.] : U.S. Fish and Wildlife Service, [2004] Online Access
* Endangered species facts [electronic resource] Electronic books U.S. Fish and Wildlife Service. [Washington, D.C.] : U.S. Fish and Wildlife Service, [2001] Online Access
* Host fish identification and early life thermal requirements for the federal endangered winged mapleleaf mussel [electronic resource] Electronic books Upper Midwest Environmental Sciences Center (Geological Survey). La Crosse, Wis. : U.S. Dept. of the Interior, U.S. Geological Survey, Upper Midwest Environmental Sciences Center, [2005] Online Access
* Hornback, Daneil; March, James; Deneka, Tony; Troelstrup, Nels; Perry, James. "Factors Influencing the Distribution and Abundance of the Endangered Winged Mapleleaf Mussel Quadrula fragos in the St. Croix River, Minnesota and Wisconsin." American Midland Naturalist Volume 136.October, 1996 278-286. Accessed April 15, 2008
* Bleam, Daniel, Cope, Charles; Couch, Karen; Distler, Donald. "The Winged Mapleleaf, Quadrula fragosa in Kansas." Transaction of the Kansas Academy of Science Volume 101(1998) 35-38. April 17, 2008
* Steingraeber, Mark, Bartsch, Michelle; Kalas, John; Newton, Teresa. "Thermal Criteria for Early Life Stage Development of the Winged Mapleleaf Mussel (Quadrula fragosa).." American Midland Naturalist 157(2006) 297-311. April 17, 2008