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Salinity of the Little Colorado River in Grand Canyon confers anti-parasitic properties on a native fish

Western North American Naturalist

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Abstract

Water in the Little Colorado River within Grand Canyon is naturally high in salt (NaCl), which is known to prohibit development of external fish parasites such as Ich (Ichthyophthirius multifiliis). The naturally high salinity (>0.3%) of the Little Colorado River at baseflow may be one factor allowing survival and persistence of larval and juvenile humpback chub (Gila cypha) and other native fishes in Grand Canyon. We compared salinity readings from the Little Colorado River to those reported in the literature as being effective at removing protozoan parasites from fish. In laboratory tests, 10 juvenile roundtail chub (Gila robusta; 61–90 mm TL) were randomly placed into each of 12, 37-L aquaria filled with freshwater, water obtained from the Little Colorado River (0.3% salinity), or freshwater with table salt added until the salinity reached 0.3%. Roundtail chub was used as a surrogate for humpback chub in this study because the species is not listed as endangered but is morphologically and ecologically similar to humpback chub. All roundtail chub infected with Ich recovered and survived when placed in water from the Little Colorado River or water with 0.3% salinity, but all experimental fish placed in freshwater died because of Ich infection. The naturally high salinity of the Little Colorado River at baseflow (0.22%–0.36%), appears sufficiently high to interrupt the life cycle of Ich and may allow increased survival of larval and juvenile humpback chub relative to other areas within Grand Canyon.

Geospatial Extents

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Salinity of the Little Colorado River in Grand Canyon confers anti-parasitic properties on a native fish
Series title:
Western North American Naturalist
Volume
72
Issue:
3
Year Published:
2012
Language:
English
Publisher:
Brigham Young University
Publisher location:
Provo, UT
Contributing office(s):
Southwest Biological Science Center
Description:
5 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
334
Last page:
338
Country:
United States
State:
Arizona
Other Geospatial:
Grand Canyon