Meeting Abstract
70.7 Monday, Jan. 6 09:30 A Conflict between Hatching and Survival in a Halophilic Fairy Shrimp (Crustacea: Anostraca) MAUSBACH, W/E*; DZIALOWSKI, A/R; Oklahoma State University; Oklahoma State University bill.mausbach@okstate.edu
Branchiopods are well known for their dormant eggs and the specific cues required to break dormancy (temperature, dissolved oxygen, light, or water chemistry). These cues are thought to be conservative to insure high survival in unpredictable environments like ephemeral pools or playas. Branchinecta potassa Belk 1979, is an endemic fairy shrimp that has only been collected in alkaline/saline ephemeral pools in the Nebraska Sandhills, Nebraska, U.S.A. Over the past three years, we conducted regional surveys showing that this species can occur in saline environments ranging in conductivity from 3.32 – 37.9 mS/cm and that presence varies annually due to fluctuations in precipitation and temperature. We aimed to identify the range of environmental conditions B. potassa can survive in by exposing its eggs to three temperatures (5, 20, and 35o) and 3 levels of conductivity (freshwater, low salinity, and high salinity). We also compared developmental rates, fecundity, and egg viability of B. potassa at the three levels of conductivity. No eggs hatched at the 5 or 35oC, but when the eggs were moved to 20o, hatching occurred within 24-36 hours at all conductivity levels. More B. potassa individuals hatched in the freshwater and low alkaline treatments than the high alkaline treatment, though there were no significant differences between the treatments. The nearly equal hatching rates of B. potassa in freshwater (<1mS/cm) and low salinity water were of particular interest, because it has yet to be found in freshwater habitats.
