Conservation of Cyprinodon nevadensis pectoralis and three endemic aquatic invertebrates in an artificial desert spring refuge located in Ash Meadows National Wildlife Refuge, Nevada
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 vii 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.