Hydroperiod shapes aquatic invertebrate communities of Sonoran Desert rock pools

Authors: Susan Washko, Michael Bogan

Year: 2022

Abstract

Hydroperiod is a strong environmental filter for aquatic life, selecting invertebrates with life histories that match the timing and duration of inundation. However, adaptations and traits may allow some taxa to survive shorter hydroperiods. Rock pools, such as those in the Sonoran Desert, are ideal study systems to test whether aquatic invertebrate communities residing in pools of different hydroperiods are different in terms of community composition and trait composition. We monitored ten rock pools in Organ Pipe Cactus National Monument, Arizona, USA, tracking the hydroperiod and sampling the aquatic invertebrates. We found that pools with shorter hydroperiods differed in both community composition and trait composition from pools with longer hydroperiods. Pools with longer hydroperiods tended to have higher species richness and indicator taxa that were mostly active dispersers, while pools with shorter hydroperiods tended to have lower species richness and indicator taxa that were desiccation-tolerant and had short life cycles. Shorter hydroperiod pools contained higher proportions of aerial passive dispersers, and consequently, lower proportions of active dispersers. Short-lived pools also had higher proportions of taxa exhibiting diapause, though diapause was common in both long and short hydroperiod pools. These results demonstrate the significance of hydroperiod as an environmental filter, giving insight into what aquatic invertebrate communities in rock pools could look like as climate change continues to alter hydroregimes.