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Saddleback darter
The saddleback darter (''Percina vigil'') is a freshwater fish native to the eastern United States. This darter species is widespread, occurring from the Escambia River drainage west to the Mississippi River basin and as far north as the Wabash River historically. Some populations have been reported in the Tennessee River drainage. The saddleback darter is aptly named as it has 5 saddle-like patterns on its dorsum, with the first occurring near the first dorsal fin and the fifth near the caudal penduncle. Adults can attain a maximum size of about 3 inches or 7.8 centimeters. The saddleback darter typically occurs over sand and gravel runs of creeks and small to medium sized rivers and is sometimes found in very shallow water. This darter's diet consists of invertebrates such as caddisfly larvae, beetles, mayflies, and stoneflies. The saddleback darter deposits eggs over sand and gravel shoals during the spring. This species has an average lifespan between 2 and 3 years.
==Geographic distribution==
The saddleback darter has a widespread but sporadic distribution throughout its range. It commonly occurs in low gradient streams from the Mississippi River drainage in southeast Indiana and Missouri southward to the Gulf Slope in the Escambia River Drainage. This fish is most common in the Gulf Slope region of its range.〔 Burr, Brooks M., Page, Lawrence M. Peterson Field Guide to Freshwater Fishes of North America North of Mexico. Houghton Mifflin Harcourt New York, NY. 2011. pg. 524. 〕 The fish has also been recorded in the Tennessee River drainages such as the Hatchie River. The saddleback darter was once found in the Wabash River, however it has been extirpated. This raises interest as to what contributed to the extirpation of this darter. Anthropogenic factors, especially siltation and excess nutrients, are likely to blame for the loss of this fish from the river. The Wabash River flows through the Corn Belt, a major agricultural area of the United States. This puts the river at great risk for increased nutrients from fertilizers and siltation from frequent disturbance of the soil. This reduction in water quality has likely been what extirpated the saddleback darter from the watershed, along with several other fish species.〔 Simpson, T.P. Biodiversity Of Fishes In The Wabash River: Status, Indicators, And Threats. 2006. Proceedings of the Indiana Academy of Science 1 15(2): 136-148.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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