HR: 0800h
AN: H51H-0872    [Abstracts]
TI: Reconstructing Two Decades of Aquatic Invertebrate Diversity and Density along an Alluvial Plain River
AU: * Rupp, D E
EM: d.rupp@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, 10 Kyle Street, Christchurch, 8004, New Zealand
AU: Arscott, D B
EM: d.arscott@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, 10 Kyle Street, Christchurch, 8004, New Zealand
AU: Larned, S T
EM: s.larned@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, 10 Kyle Street, Christchurch, 8004, New Zealand
AU: Schmidt, J
EM: j.schmidt@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, 10 Kyle Street, Christchurch, 8004, New Zealand
AB: Lotic invertebrate communities vary in time and space in response to flow variability. When stream flow data exist they can be used to predict community responses to flow conditions. It is rare, however, that long-term, high- frequency hydrologic data exist for more than one or a few points along a river. This data scarcity in space restricts our understanding of the spatial variability of biotic response in rivers whose hydrology varies greatly along their course. To explore space-time variation in flow-invertebrate relationships, we reconstructed two decades of daily river flows down the length of the Selwyn River mainstem as it crosses the Canterbury Plains of SE New Zealand. This 60 km-long mainstem is perennial at the upper and lower ends and ephemeral and intermittent in its middle reaches. Flow at 18 cross-sections along the mainstem was calculated as a function of the flow at two stage recorders located in the perennial reaches. Data from 38 months of intermittent gauging at the cross- sections was used to calibrate model parameters. Flow interpolation between cross-sections provided longitudinal continuity. Hydrologic metrics (e.g., frequency and duration of dry and wet phases) were derived from the reconstructed time series. These metrics were used to test relationships between invertebrate taxonomic richness and density and hydrological conditions at 15 sites along the river where invertebrate samples had been collected. Several hydrologic metrics were significant predictors of the invertebrate metrics. Multivariate linear models were used to hind-cast invertebrate richness and density in time and space along the entire study domain.
DE: 1813 Eco-hydrology
DE: 1830 Groundwater/surface water interaction
DE: 1856 River channels (0483, 0744)
DE: 1860 Streamflow
SC: Hydrology [H]
MN: 2007 Fall Meeting