Summer Food Habits of Fishes from Two Springs in East-Central Nevada

Abstract

This study examined the summer food habits of Crenichthys baileyi albivallis, Rhi- nichths osculus velifer, and Catostomus clarki intermedius from Preston Big Spring, Nevada, and Crenichthys nevadae from Big Spring at Lockes Ranch, Nevada. The two spring habitats are quite dissimilar. Preston Big Spring is a large, cool spring with a large algal flora dominated by chlorophytes, and a diverse invertebrate fauna. Big Spring at Lockes Ranch is warm, somewhat smaller, and harbors a small algal flora dominated by cyanophytes, as well as a depauperate fauna. Crenichthys b. albivallis was primarily herbivorous during the summer when it consumed large volumes of the abundant green algae. Some opportunistic individuals however, consumed mostly insect larvae. Rhinichthys o. velifer was omnivorous, consuming a wide variety of foods. The diet of Catostomus c. intermedius consisted of plant material and some detritus. Crenichthys nevadae was carnivorous, preferring ostracods and avoiding the blue-green algae. The ecology of many Great Basin fishes has been essentially ignored. With the incidence of threats to desert ecosystems increasing, the need for an understanding of the dynamics of these systems is acute. Knowledge of the food habits of the fishes is one important step in understanding the dynam- ics of aquatic ecosystems. To this end we have examined the summer feed- ing ecology of the desert sucker, Catostomus (Pantosteus) clarki intermedius; speckled dace, Rhinichthys osculus velifer; and White River springfish, Cre- nichthys baileyi albivallis; from Preston Big Spring, which is located on the course of the pluvial White River in White Pine County, Nevada. The only other fish historically inhabiting Preston Big Spring, the White River spinedace, Lepidomeda albivallis, was not examined because it has been extirpated from the spring. Summer feeding ecology of the Railroad Valley springfish, Crenichthys nevadae, from Big Spring at Lockes Ranch was also examined to allow comparison of the two species of Crenichthys. Big Spring at Lockes Ranch is located in Nye County, Nevada, approximately 60 km southwest of Preston Big Spring. Little life history information has been published concering these fishes. Fifteen Catostomus clarki from the Virgin River contained largely amor- phous organic material with filamentous algae, sand, and an occasional Diptera larva (Cross, 1975). Smith (1966) reported the foods of C. clarki to consist of microscopic periphyton and other organic debris, and occasionally invertebrates. No data have been published for the subspecies inhabiting the White River system. No life history information has been published for R. o. velifer, but information is available for related forms of speckled dace, which are typically carnivorous, browsing on benthic invertebrates (Moyle, 1976). The food habits of Crenichtyhs baileyi are unknown; however, the