Multiple stressors in coupled river–floodplain ecosystems

Abstract

Summary: 1. Riverine floodplains are highly complex, dynamic and diverse ecosystems. At the same time they are among the world’s most threatened ecosystems because of the pervasiveness of dams, levees and other factors such as rapid spreading of non‐native species. Hence, floodplains are ideal systems to study ecological impacts of multiple stressors at the local, regional and catchment scale. 2. Concepts such as the subsidy‐stress hypothesis and the stress‐induced community tolerance concept have been formulated to study the effect of stressors on aquatic and terrestrial ecosystems, as well as on their functional linkages. 3. Riverine floodplains are pulsed ecosystems with distinct flow, sediment, resource and thermal pulses – thereby creating distinct ‘windows of ecological opportunity’. Human modifications that truncate or amplify theses pulses will have cascading effects on river–floodplain interactions by shifting the thresholds of connectivity, resilience or resistance – causing drastic regime shifts. 4. Most aquatic insects and pond‐breeding amphibians have complex life cycles with aquatic and terrestrial stages. They are exposed to different stressors in their aquatic and terrestrial realm. Because most life history functions of aquatic insects are restricted to a short terrestrial period, we need to fully integrate the ‘airscape’ into the future management of river–floodplain ecosystems. 5. Riverine floodplains integrate and accumulate multiple stressors at the catchment level, as reflected by distinct catchment fingerprints. Based on the European Catchment Data Base we provide spatially explicit information on multiple stressors; a key prerequisite for setting priorities in conservation and management planning. 6. Thematic implications: the management of stressed river and floodplain ecosystems is a major challenge for the near future and water managers worldwide. Management approaches need to be adaptive and embedded within a catchment‐wide concept to cope with upcoming pressures originating from global change.