Ed Chester

Intermittent rivers and ephemeral streams (IRES) are temporally and spatially dynamic ecosystems, experiencing alternating wet and dry phases and supporting both aquatic and terrestrial habitats. For aquatic species to persist in these variable habitats, they must be resistant or resilient to disturbances such as flow cessation and drying. Resistance mechanisms include tolerance of extreme physicochemical conditions and possession of desiccation-resistant dormant stages, whereas resilience mechanisms require the ability to disperse instream or overland. Similarly, terrestrial species inhabiting IRES during dry phases must be resistant or resilient to periodic inundation of their habitat. Resistance and resilience processes interact to facilitate community recovery after unfavorable periods (e.g., drying for aquatic taxa, flooding for terrestrial taxa). Human disturbances such as flow diversions and streambed gravel mining alter recovery pathways and affect the long-term persistence of aquatic and terrestrial species in IRES.