Biotic and abiotic factors influencing the distribution of the huachuca springsnail (pyrgulopsis thompsoni)

The Huachuca springsnail (Pyrgulopsis thompsoni) is a species of concern inhabiting springs of the Huachuca Mountains in southeastern Arizona, USA. We documented springsnail distribution and examined the major abiotic and biotic factors influencing springsnail abundance at eight spring channels before and after the onset of seasonal summer rains in 2003. Of the abiotic factors examined (total dissolved solids, pH, distance from spring source, spring channel, water temperature, and dissolved oxygen), only spring channel and total dissolved solids were strongly associated with springsnail abundance. However, correlation of total dissolved solids with pH, temperature, dissolved O₂, and distance downstream necessitated further exploration of these explanatory variables. We found that sampling locations with P. thompsoni were characterized by cooler, more oxygenated, and less-occluded water conditions relative to sampling locations without springsnails. Springsnail abundance was positively associated with abundance of caddisfly larvae (Helicopsyche sp.) but not significantly associated with abundance of a co-occurring snail (Physa sp.). The most important outcomes of this study were the documentation of major factors associated with springsnail abundance, and recovery of springsnails at greater distances downstream than previously documented.