''Percina aurora'', the pearl darter is a small species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, a darter from the subfamily

Etheostomatinae Etheosomatidae is a species rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The famil ...

, part of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Percidae The Percidae are a family of ray-finned fish, part of the order Perciformes, which are found in fresh and brackish waters of the Northern Hemisphere. The majority are Nearctic, but there are also Palearctic species. The family contains more than ...

, which also contains the

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Per ...

es, ruffes and pikeperches. It is native to the United States, where it is known only from

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a U.S. state, state in the Deep South and South Central United States, South Central regions of the United States. It is the List of U.S. states and territories by area, 20th-smal ...

and

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Mis ...

, but seems no longer to be present in the

Pearl River The Pearl River, also known by its Chinese name Zhujiang or Zhu Jiang in Mandarin pinyin or Chu Kiang and formerly often known as the , is an extensive river system in southern China. The name "Pearl River" is also often used as a catch-all ...

. Its total area of occupation is under , it is a rare species and a candidate for federal protection. It is threatened by siltation, pollution,

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and urbanization, and as a result, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natur ...

has classified its conservation status as being "

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

Description

This fish was described as a species in 1994. It had previously been included in '' Percina copelandi''. The pearl darter grows up to 57 (female) to 64 (male) millimeters long. It has a black spot at the base of the tail fin. The breeding male has a few dark bands. It is usually mature around one year of age.

Distribution and habitat

This fish is now limited to the

Pascagoula River The Pascagoula River is a river, about 80 miles (130 km) long, in southeastern Mississippi in the United States. The river drains an area of about 8,800 square miles (23,000 km²) and flows into Mississippi Sound of the Gulf of Mexico. ...

drainage in

and

states in the

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 U.S. state, states, a Washington, D.C., federal district, five ma ...

. It has apparently been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from the

.USFWS
Species Assessment and Listing Priority Assignment Form.
April 4, 2012. The total range is about 200 square kilometers. This fish can be found in riffles and shallow, fast-moving river water. Higher river flows in the spring help to disperse the juveniles. Its favored habitat is unknown but its habitat requirements are likely similar to those of ''P. copelandi''. This related species feeds on

midge A midge is any small fly, including species in several families of non- mosquito Nematoceran Diptera. Midges are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. Some m ...

s and small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

s. Threats to this species include

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

via runoff of fertilizers, pesticides, oil, and other materials. Sediment and silt degrade the habitat. Hurricane Katrina impacted the local area, washing pollutants and salt water into the river. The release of

dioxin Dioxin may refer to: * 1,2-Dioxin or 1,4-Dioxin, two unsaturated heterocyclic 6-membered rings where two carbon atoms have been replaced by oxygen atoms, giving the molecular formula C4H4O2 * Dibenzo-1,4-dioxin, the parent compound also known ...

into the Pascagoula system has been mitigated, but dioxin embedded in the substrate may be stirred up at times, entering the water. Riverside

urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly t ...

may lead to organic wastes being released into the water. Sand and gravel mining occur in the river system and destabilize the substrate. Habitat destruction has led to the species' populations being split and isolated, creating a

disjunct distribution In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but considerably separated from each other geographically. The causes are varied and might demonstrate either the expansion or contraction of a s ...

. This split makes it more likely that populations will become extirpated.

References

External links

''Percina aurora'' photo.
National Geographic. {{Taxonbar, from=Q3764478

aurora An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in high-latitude regions (around the Arctic and Antarctic). Auroras display dynamic patterns of bri ...

Taxa named by Royal Dallas Suttkus Taxa named by Bruce A. Thompson Fish described in 1994 ESA threatened species