User:Nhwon19/Desert pupfish

= Desert pupfish = The desert pupfish (Cyprinodon macularius) is a rare species of bony fish in the family Cyprinodontidae. It is a small fish, typically less than 7.62 cm (3 in) in length. Males are generally larger than females, and have bright-blue coloration, while females and juveniles are silvery or tan. A notable attribute of the desert pupfish is their ability to survive in environments of extreme salinity, pH, and temperature, and low oxygen content. The desert pupfish mates in a characteristic fashion, wherein compatible males and females will come in contact and collectively jerk in an s-shape. Each jerk typically produces a single egg that is fertilized by the male and deposited in his territory. Breeding behavior includes aggressive arena-breeding and more docile consort-pair breeding.

Description
The desert pupfish is a small fish that is typically less than 7.62 cm (3 in) long; males are larger than females and generally have more vivid markings, especially during breeding seasons. Females and juveniles typically have tan or olive backs and silvery sides with narrow, dark vertical bars situated laterally. These bars are often interrupted to give the impression of a disjunct, lateral band. During mating season, males become bright blue on the dorsal portion of the head and sides, and yellow or orange on the caudal fin and posterior caudal peduncle. The dorsal profile of the desert pupfish is smoothly rounded, while its body is thickened and laterally compressed. The desert pupfish has a protruding mouth equipped with tricuspid teeth.

Reproduction
The breeding season of the desert pupfish typically occurs during early spring and into winter when water temperatures exceed about 20 °C. Under conditions of abundant food and suitable temperature, the desert pupfish may become sexually mature as early as six weeks of age. Though they may start to breed during their first summer, most pupfish do not reproduce until their second. Breeding behavior includes both territorial arena-breeding (high aggression) and consort-pair breeding (low aggression). The former occurs in large habitats with high primary productivity, limited breeding substrates, and high population density, and it is the most common; the latter occurs in habitats with low primary productivity, abundant breeding substrates, and low population density.

During the breeding season, male pupfish establish and actively patrol and defend individual territories that are typically less than 1 meter deep and 1–2 meters in area; these territories vary in size based on individual fish size, density of other male pupfish, and water temperature, and are associated with small structures or incongruities of substrate. Adult females will swim in loose schools and forage inconspicuously. When a female is ready to spawn, she will leave the school to enter the territory of an attractive male, and the mating process described above will commence.

Temperature plays a significant factor in egg production. The most optimal temperature for eggs to be produced typically occurred at a constant temperature of 24-32 C and a fluctuating temperature of 32-28 and 36-28 C. Additionally, the quality of eggs was affected by temperature, with temperature and yolk diameter having an inverse relationship. The salinity the egg is placed in also has an effect on reproductive performance. The most optimal reproductive performance occurred at 10% salinity and decreased when above or below 10%.

Management Factors
While the desert pupfish contains a remarkable tolerance to extreme conditions, the species is listed as endangered as of 1986. The desert pupfish has been the focus of many conservation studies and attempts. Beginning in the late 1800's, the disappearance of the fish has been associated to the increase of human activities.

Specifically, the threats to desert pupfish survival include the destruction of habitat, including loss and/or degradation of habitat through groundwater pumping and water diversion; contamination from agricultural return flows and other contaminants; physical changes in water quality; and pesticide run-off. In addition to these anthropogenic effects, desert pupfish have also been threatened by disease and predation due to invasive and nonnative species. The most recent decline of desert pupfish have shown to be correlated with environmental competition, predation and behavioral activities that interfere with reproduction, though the direct effects of these factors are unknown.

Various management factors have been suggested as beneficial towards saving the desert pupfish, including the control and management of exotic and invasive species in pupfish habitats; the maintenance of water levels, quality, and the proper functioning condition of ponds, springs, and drains; the restoration and enhancement of degraded habitat; and the establishment of large primary refuge populations for each group of wild C. macularius. The reintroduction of the desert pupfish to wild habitats has been moderately successful, with the establishment of captive or refuge desert pupfish populations has been more fruitful. Water management has been largely cited as having the greatest impact on the survival of C. macularius.