Effects of Physical‐Chemical Factors on the Distribution and Occurrence of Some Southeastern Wyoming Phyllopods

Abstract

Field and laboratory evidence demonstrates that differences in tolerance to salinity and temperature of phyllopods notably affect their habitat types and seasonal occurrence. Oxygen concentration and pH are of lesser ecological consequence. The 11 phyllopods studied are categorized according to their seasonal occurrence and habitat salinities. For example, based on the tolerance of both eggs and adults, Branchinecta lindahli is eurythermal and euryhaline, whereas Triops longicaudatus is stenothermal and stenohaline. Though some adult phyllopods endure substantial ranges in salinity and temperature, their eggs are not necessarily so adapted. In some instances egg hatchability is impeded by environments not hostile to adult shrimp. Phyllopod eggs are, therefore, instrumental in defining when and where a particular species occurs. Ephemeral ponds with moderately high magnesium concentrations may be hostile to some phyllopods.

Desert Potholes: Ephemeral Aquatic Microsystems

“…These findings are in agreement with previous suggestions that total salt content of freshwater ephemeral pools would be low throughout the year as a result of low initial salt concentrations (Horne, 1967;Williams, 1985;Scholnick, 1994). Several studies have suggested that salt weathering could play a role in pothole formation (e.g., Netoff et al, 1995), however, our data suggest that this is unlikely.…”

Laboratory studies of factors affecting egg hatch of triops longicaudatus (LeConte) (Notostraca : Triopsidae)

“…Although egg hatch in the laboratory was observed over a wide range of pH (3 .10-10 .01), the waters in which C longicaudatus were found in rice fields centered about neutrality . Horne (1967) observed that in pools inhabited by C longicaudatus pH ranged from 7 .1 to 8 .5 .…”

Hatching response to temperature along a latitudinal gradient by the fairy shrimp Branchinecta lindahli (Crustacea; Branchiopoda; Anostraca) in culture conditions

“…Other studies have demonstrated that anostracan egg hatching is increased by favourable temperatures (Hall, 1961;Broch, 1965;Moore, 1967;Daborn, 1976;Modlin, 1982), suppressed by unfavourable temperatures (Hall, 1961;Nourisson, 1961;Broch, 1965;Moore, 1967; Mossin, 1986;Saiah and Perrin, 1990;Belk and Nelson, 1995), and that variation in annual appearance of co-occurring species is attributed to variation in favourable temperatures between species (Moore, 1963;Prophet 1963c;Horne, 1967Horne, , 1971. Moore (1967) noted in Streptocephalus sealii Ryder, 1879 populations from a pool in Louisiana, USA, that the optimal hatching temperature was 21°C, however hatching percentage increased if eggs were subjected to a temperature fluctuation from 19 to 23°C over a ten hour period every day.…”

“…This broadly distributed species is recorded from a range of endorheic temporary wetland habitat types from dryland regions, including: alkaline vernal pools, prairie potholes, and slightly saline pools and playas (Hartland-Rowe, 1965;Horne, 1967Horne, , 1971Belk, 1977bBelk, , 1983Eng et al, 1990;Gonzales et al, 1996;Eriksen and Belk, 1999;Maeda-Martinez et al, 2002). Horne (1967Horne ( , 1971 reported that B. lindahli is remarkably tolerant of a wide range of dissolved salts types and concentrations. This species is known from turbid and clear water habitats (Eng et al, 1990).…”