Influence of hydroperiod on aquatic food-web structure and energy production in a floodplain wetland: implications for environmental flow management

Context Environmental water is often used to manage floodplain wetlands that support many taxa, both terrestrial and aquatic. It is important to optimise the managed hydroperiod to maximise the provision of aquatically derived resources from wetlands.Aims To test the hypothesis that increasing hydroperiod affects food-web structure and energy production in floodplain wetlands.Methods Fatty acids and stable isotopes of delta 13C and delta 15N were used to define food-web structure, and estimate total energy production throughout a managed inundation event in a wetland in the northern Murray-Darling Basin.Key results Food-web complexity increased with an increasing hydroperiod in line with predictable patterns of community assemblage development, before reducing sharply immediately prior to drying. Energy availability increased with an increasing hydroperiod and there was a strong correlation (rho = 0.669, P = 0.0001) between energy availability and fatty acid concentration, which was in turn related to patterns of taxon occurrence.Conclusions and implications Hydroperiod exerts a strong influence on aquatic invertebrate community trophic dynamics and energy provision. Planned flows should support maturation and stabilisation of the invertebrate community to optimise energy provision to consumers. We examined food-web structure and energy production during a managed flow in a floodplain wetland and found that duration of inundation had a significant effect on trophic dynamics. Sampling at three stages in the inundation cycle, we were able to describe changes in patterns of resource use and link energy provision and food quality to phases of invertebrate community succession.This article belongs to the collection Environmental Flows in Northern Murray-Darling Basin.