Animal Assemblages in Temporary Desert Rock Pools: Aspects of the Ecology of Dasyhelea sublettei (Diptera:Ceratopogonidae)

Abstract

Twenty-three taxa of aquatic macroinvertebrates and amphibians were found in 50 desert ephemeral rain-filled rock pools in the desert near Moab, Utah. Only one pool contained no animals. The most common 12 taxa of animals tended to occur in three distinct assemblages, characterized respectively by Dasyhelea sublettei (Ceratopogonidae--biting midge larvae), Triops longicaudatus (Notostraca--tadpole shrimps) and Notonecta undulata or N. kirbyi (Notonectidae--back-swimmers). These assemblages were correlated with increasing pool size in the above sequence, and, by implication, with duration of the aquatic habitat. Feeding trials suggested that D. sublettei was excluded from larger pools by predatory Triops and Notonecta. Omnivorous feeding habits and some resistance to desiccation allowed D. sublettei to find a refuge in the most ephemeral pools.