Three saline evaporation ponds formed by wastewater from a solar energy-generating facility near Harper Dry Lake in the Mojave desert of California were compared for differences in the communities of benthic and planktonic invertebrates and algae present along with avian visitation and foraging activity. Under lower salinity conditions the predatory water boatman Trichocorixa reticulata was abundant and eliminated the planktonic filter-feeding brine shrimp (Artemia franciscana) thus permitting high
phytoplankton densities. At high salinities where Trichocorixa could not survive, Artemia were abundant and grazing of phytoplankton kept waters clear except during the winter dormancy of brine shrimp. Intermediate salinity levels support co-existing predator and prey populations early in the growth season (before the Trichocorixa have matured). Salinity controls a cascading trophic effect of predators on consumers on primary producers in the planktonic food chain. Birds foraged primarily on the benthic
brine fly Ephydra gracilis, found in greatest abundance at moderate salinity in shallow water. Though winter and spring visitation were greater in the high salinity pond when larvae and pupae were dense (but small), most feeding activity occurred at the moderate salinity pond in summer where biomass of Ephydra was maximum. High salinity inhibited E. gracilis growth rate, body size and emergence success
Keywords: trophic cascade, salt tolerance
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA