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Description:
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The Warm Springs Complex (WSC ) is one of four management units within Ash Meadows National Wildlife Refuge . It contains six low -discharge warm spring systems with individual flows ranging from 1 .13 x 10 -4 to 1 .98 x 10 -4 cubic meters per second and spring -source water temperatures ranging from 28o to 33 .5oC year round . School Springs is one component of the WSC and its spring source is the warmest . This spring has undergone dramatic anthropogenic transformation since at least the 1930s . In 1969 the Bureau of Land Management (BLM ) increased pool habitat in School Springs in an effort to preserve the endangered Warm Springs pupfish , Cyprinodon nevadensis pectoralis . Four concrete ponds were constructed at School Springs in 1983 to further increase available habitat to C . n . pectoralis . During the summer of 2008 , the School Springs refuge was completely renovated : the large concrete ponds were removed and a “naturalized” channel consisting of pools , runs , riffles , and a wash was created . There were three primary objectives of this renovation : (1 ) eradicate three aquatic non -native species including western mosquitofish Gambusia affinis , red swamp crayfish Procambarus clarkii , and red -rimmed melania Melanoides tuberculatus ; (2 ) improve amount of suitable habitat for the endangered Warm Springs pupfish and three aquatic invertebrates (P . pisteri , S . c . calida , A . relictus ) , that are endemic to the WSC ; and (3 ) test hypotheses concerning endemic fish and invertebrate habitat use and distribution inherent in the design of the refuge .
Based on my study , two of the aquatic non -native species , G . affinis and P . clarkii , were successfully eradicated , but M . tuberculatus was not . My results also
Texas Tech University , Darrick S . Weissenfluh , December 2010
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indicate C . n . pectoralis use pool habitat more frequently than any other habitat type , regardless of life stage ; however , they were captured in all habitat types and the fish may be distributed throughout the system from the spring source to the wash . Habitat type was a better predictor of C . n . pectoralis presence than water volume , regardless of the season , which further supports the importance of creating pool habitat for conservation of C . n . pectoralis in Ash Meadows .
Endemic aquatic invertebrates were translocated into the upper 20 m of School Springs refuge and , as of September 2010 , continue to persist . The median -gland Nevada springsnail Pyrgulopsis pisteri is narrowly distributed in the upper 20 m of School Springs and , therefore , has not dispersed downstream of the translocation site . Both the Devils Hole warm springs riffle beetle Stenelmis calida calida and the Warm Springs naucorid Ambrysus relictus are seasonally distributed throughout the stream channel , but are restricted to the upper 40 m of stream channel during the winter . P . pisteri , S . c . calida , and A . relictus presence was not associated with substrate type , but their presence was associated with pool and riffle habitat types ; however , the pool habitat in this case was the spring source . On occasional night visits to School Springs refuge in the summer of 2009 , I observed numerous S . c . calida and A . relictus . These observations suggest night surveys may be appropriate for monitoring of A . relictus and S . c . calida populations in School Springs and elsewhere . |