Local disturbance history and habitat parameters influence the microdistribution of stream invertebrates.

1. We investigated the effects of local disturbance history and habitat parameters (abiotic and biotic) on the microdistribution of benthic invertebrates during several floods in two streams, the Schmiedlaine in Germany (four events) and the Kye Burn in New Zealand (two events). 2. Bed movement patterns were quantified using metal-link scour chains. Before and after each flood, quantitative invertebrate samples were taken from replicate bed patches that had experienced sediment scour, fill or remained stable. 3. Patterns of invertebrate density in the different bed stability types (i.e. scour, fill, stable) varied between floods, sampling dates and streams, but invertebrate density was highest in stable patches in >50% of all the patch type effects detected and lowest in fill patches in 75% of all detected effects. Stable bed patches acted as a refugium for Liponeura spp. and Leuctra spp. in the Schmiedlaine and for Hydracarina and Deleatidium spp. in the Kye Burn. 4. Averaged across both streams, only near-bed current velocity was correlated with invertebrate distribution on the streambed more often than disturbance history. In the Kye Burn, disturbance history and water depth were the most influential habitat parameters. 5. Our results suggest that a thorough understanding of the microdistribution of benthic invertebrates requires knowledge of disturbance history, as well as more readily measured habitat parameters such as current velocity or water depth. [ABSTRACT FROM AUTHOR]