Bruneau Hot-Spring Springsnail (Pyrgulopsis bruneauensis). 1999 Annual Monitoring Report

This report presents the 1999 monitoring results from four sites near Indian Bathtub in southwestern Idaho that contain, or have contained, populations of the Bruneau Hot-spring Springsnail (Pyrgulopsis bruneauensis) and compares them with results from previous years. Three of these sites were monitored in 1990 and 1991 by Mladenka (1992), in 1992 by Robinson et al. (1992), in 1993 by Royer and Minshall (1993), in 1994, 1995, 1997 by Varricchione and Minshall (1995a, 1996, 1997, 1998) and in 1998 by Myler and Minshall (1999). An additional seep at Site 3 (New Seep) was included in the 1994, 1995, 1997, 1998, and 1999 Springsnail monitoring efforts.

Springsnails have recolonized Hot Creek from the relict population found within a 1.80 m seep that drained into Hot Creek (Site 1). Experiments conducted in 1999 by Cary Myler (MS thesis) bypassed the thermal barrier (Myler and Minshall 1999) with a segment of pipe which acted as a bridge for snail movement. Once Springsnails regained their presence in Hot Creek, large stable substrate were added near the small seep (Myler, unpublished data). A fish exclosure was constructed to eliminate possible predation from Tilapia (Myler, unpublished data). As of November 1999, 300-400 Springsnails were found upstream and downstream of the confluence of the small seep but within the boundaries of the fish exclosure (Myler, unpublished data).

In 1999, the U.S. Fish and Wildlife Service (USFWS) recognized that present monitoring locations were not providing a representative overview of the status of the Bruneau Springsnail over its entire range. A cooperative effort between the USFWS, Idaho State University (ISU), and the Bureau of Land Management (BLM) was initiated. Twenty-one sites, which include the five monitoring sites in this report, were established over the 4 km range of present spring locations. Factors included in site selection included location, Springsnail density, accessibility, and discharge monitoring.