Life on the edge: rotifers from springs and ephemeral waters in the Chihuahuan Desert, Big Bend National Park (Texas, USA)

Here we describe an on-going study of the rotifers inhabiting a sampling of springs (seeps), streams, ponds, tanks (diked ephemeral streams), and huecos and tinajas (small and large rock pools) of Big Bend National Park, a 3.23 x 10(5) ha region of the northern Chihuahuan Desert located in southwestern Texas (USA). We collected samples from planktonic, littoral, and benthic habitats comprising 92 sites representing 23 different aquatic systems. We documented 19 rotifer families (17 moriongonont; 2 bdelloid) comprising 32 genera and 94 taxa. Of these, 70 were identified to species; 24 taxa (14 monogononts and 10 bdelloids) remain unidentified; several may be new to science. Redundancy Analysis revealed significant associations between environmental parameters and species distributions among water sources. Highest species richness was found in more permanent habitats such as ponds and springs while species associated with rock pools were associated with high conductivity and temperature.