A Resurvey of Springsnails in and near Ash Meadows National Wildlife Refuge 31 Years Later

Authors: Geoff Moret, Erin Orozco, Michael Schwemm

Year: 2018

Abstract

In 1985 and 1986, Robert Hershler and Don Sada conducted a comprehensive survey for springsnails on and near the newly-established Ash Meadows National Wildlife Refuge. They documented the distribution of 11 species of springsnails, including nine newly-described species, and included field water quality data and a brief description of the habitat at each spring. In the previously surveyed 47 springs, one spring was dry (Mexican Spring), and springsnails occurred in 36. The relatively widespread Pyrgulopsis micrococcus was the only springsnail found in 9 springs. One or more of the remaining ten species (Tryonia variegata, Tryonia angulata, Tryonia ericae, Tryonia elata, Pyrgulopsis erythropoma, Pyrgulopsis crystalis, Pyrgulopsis nanus, Pyrgulopsis isolatus, Pyrgulopsis fairbanksensis, and Pyrgulopsis pisteri) were found in 27 springs. Here, we present a 2017 resurvey of 26 springs with endemic springsnails previously visited by Hershler and Sada (the 27th spring is Devils Hole, which has regular surveys of all invertebrates). Our methods include the enumeration of individuals by genus (Tryonia or Pyrgulopsis), basic field water quality measurements, habitat description and the observation of potential environmental stressors. Samples were also collected for future genetic analysis. Seven of the 26 resurveyed springs were dry. Two species (T. elata and P. isolatus) were not found in the springs where previously reported as endemic. In addition, Tryonia occurred in only one of the two springs where T. ericae was found in the original survey, and only a single individual Pyrgulopsis was found is the spring where P. crystalis previously occurred. Our results show that springsnail presence is generally robust geographically over approximately 30 years, however, the distribution of some species can change significantly over that time, even within a protected area. More surveys and species-level identification are needed to verify non-detections reported in the 2017 survey.