Life history and population dynamics of Daphnia in seven ephemeral pools in Red Rock Canyon, Nevada

Priscilla Kathleen Bowman, University of Nevada, Las Vegas


Seven ephemeral rock pools in Red Rock Canyon, Nevada were visited bimonthly over twelve months and sampled for resident zooplankton species. Population dynamics and life history characteristics of two Daphnia species, D. pulex and D. obtusa were analyzed with incidental attention given to an additional cladoceran, Moina sp. Aspects of the physical, chemical and biological environment were measured and evaluated. The behavior of these daphnid populations appears to be driven by the extreme seasonality of rock pool ecosystems between episodic disturbances of drought and deluge. No causal relationships between Daphnia population size or patterns of temporal change and abiotic factors appear to exist. The availability and duration of water limits population growth. When conditions are favorable, rapid population growth apparently occurs via obligate parthenogenesis. This is the first systematic study of any Daphnia species in the Mojave Desert, or in any ephemeral aquatic habitat within a desert region.