Hatching dynamics of invertebrate dormant stages in temporary ponds are influenced by multiple hydrations

Abstract

Dormancy termination in aquatic invertebrates depends on multiple environmental cues, notably hydration, and on the invertebrates’ ability to respond to each new flooding event. Hatching of dormant stages is important to ecological processes in intermittent wetlands, such as recolonization of biota after dry periods and maintenance of foodweb dynamics. However, hatching responses of invertebrates to hydration cues can show considerable spatial and taxonomic variation, and consequences of this variation to the hatchling assemblage structure are still unclear. In this study, we tested how multiple hydrations in series affect hatching dynamics and assemblage structure of invertebrate fauna that hatch from sediments of temporary ponds. We hypothesized that variable responses to flooding among taxa would influence the hatchling assemblage structure. We predicted that hatchling richness would show little or no variation across hydration events but that hatchling composition would vary among hydration events. We performed an ex-situ hatching experiment to expose the sediments of 12 temporary ponds in the southern Brazilian Coastal Plain to a sequence of 3 hydration events and to induce hatching of invertebrates from dormant stages in the sediments. Hatchling composition, but not richness, differed among the 3 hydration events. Additionally, hatchling composition showed marked short-term variation within each hydration event. We showed that dormancy dynamics of aquatic invertebrates in subtropical temporary ponds are influenced by multiple hydration cues. Our results have important implications for biodiversity assessment and management of temporary ponds and for understanding the effects of changing hydrologic regimes on the ecological processes of intermittently flooded ecosystems.