Increase in coarse sediment transport associated with disturbance of gravel river beds by signal crayfish (Pacifastacus leniusculus)

摘要: There is growing acknowledgement of the interaction between animals and river bed on which they live implications biological activity for geomorphic processes. It has been observed that signal crayfish (Pacifastacus leniusculus) disturb gravel substrates, potentially promoting sediment transport impacting ecological communities. However, mechanisms involved extent their impact remain poorly understood, especially in relation to other processes affect grain mobility gravel-bed rivers. A series flume experiments, using loose water-worked beds narrowly graded sizes were exposed 6 h under low-velocity flows, showed a substantial increase number grains entrained by subsequent higher-velocity flows when compared with control runs never introduced. Crayfish alter topography substrate constructing pits mounds, protrusion. When walking foraging, also fabric reorienting changing friction angle surface grains. In surfaces, this rearrangement shown lead statistically significant, partial reversal structuring had achieved antecedent flow. For these previously entrainment arising from disturbance was nearly twice as great. This suggests crayfish, an increasingly widespread invasive species temperate latitudes beyond native NW North America, have potential enhance coarse-grained bedload flux altering structure reducing stability study illustrates further importance acknowledging mobile organisms conditioning assessing mechanics context predicting flux.