Endemic Snail

(Submitted Abstract to the 2002 National Speleological Society Meeting, Camden, Maine)

Population Studies of the Endemic Snail Physa spelunca (Gatropoda:Physidae) from Lower Kane Cave, Wyoming

Megan L. Porter, Department of Zoology, Brigham Young University, Provo UT 84602

Sarah Russell, Department of Zoology, Brigham Young University, Provo, UT 84602

Annette S. Engel, University of Texas at Austin, Department of Geological Sciences, Austin, Texas 78712

Libby Stern, University of Texas at Austin, Department of Geological Sciences, Austin, Texas 78712

Most cave ecosystems are energetically limited, depending on the transport of organic materials into the system from the surface.  In contrast, Lower Kane Cave, Wyoming contains sulfidic waters that support abundant communities of sulfur-oxidizing microbes, which use chemical energy to produce food. Other cave systems containing comparable microbial communities have abundant and diverse invertebrate fauna associated with this type of sulfur-based production (e.g. Movile Cave, Romania; Frasassi Caves, Italy).  While the invertebrate fauna assemblage is not as diverse as similar systems, Lower Kane Cave contains an extremely abundant, endemic, cave-adapted aquatic snail, Physa spelunca.  Stable isotope analyses show that P. spelunca sampled from within the cave feed on the microbial mats, with both  d¹³N (7.5 ‰) and d¹³C (-36 ‰) values exhibiting typical trophic effects.  In contrast, snails collected from the entrance of the cave had d¹³C values (–26 ‰) typical from terrestrial C3 photosynthesis, indicating a shift to surface productivity.  The abundant microbial food source has led to extremely high population densities in the immediate vicinity of the mats, with estimates as high as 6800 individuals/m².  Additionally, although P. spelunca was originally described as exhibiting classic troglomorphic features (i.e. eye reduction and pigment loss), observations of the Lower Kane Cave population indicate that there are at least two other color morphs present (red and black).  Preliminary investigations into the genetics of this unusual cave population have been initiated based on internal transcribed spacer gene regions in order to estimate genetic diversity and evaluate population structure.