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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >Increase coarse sediment transport associated with disturbance of gravel river beds by signal crayfish (Pacifastacus leniusculus)
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Increase coarse sediment transport associated with disturbance of gravel river beds by signal crayfish (Pacifastacus leniusculus)

机译：信号小龙虾（Pacifastacus leniusculus）增加了与砾石河床扰动有关的粗沙输送

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摘要

There is growing acknowledgement of the interaction between animals and the river bed on which they live and the implications of biological activity for geomorphic processes. It has been observed that signal crayfish (Pacifastacus leniusculus) disturb gravel substrates, potentially promoting sediment transport and impacting ecological communities. However, the mechanisms involved and the extent of their impact remapoorly understood, especially relation to other processes that affect gramobility gravel-bed rivers. A series of flume experiments, using loose and water-worked gravel beds of narrowly graded grasizes that were exposed to 6h of crayfish activity under low-velocity flows, showed a substantial increase the number of grains entrained by subsequent higher-velocity flows when compared with control runs which crayfish were never introduced. Crayfish alter the topography of their substrate by constructing pits and mounds, which affect graprotrusion. When walking and foraging, they also alter gravel fabric by reorienting and changing the friction angle of surface grains. water-worked surfaces, this fabric rearrangement is shown to lead to a statistically significant, partial reversal of the structuring that had been achieved by antecedent flow. For these previously water-worked surfaces, the increase entrainment arising from disturbance by crayfish was statistically significant, with gratransport nearly twice as great. This suggests that signal crayfish, an increasingly widespread invasive species temperate latitudes beyond their native NW North America, have the potential to enhance coarse-grained bedload flux by altering the surface structure of gravel river beds and reducing the stability of surface grains. This study illustrates further the importance of acknowledging the impact of mobile organisms conditioning the river bed when assessing sediment entrainment mechanics the context of predicting bedload flux.
机译：人们越来越认识到动物与它们赖以生存的河床之间的相互作用以及生物活动对地貌过程的影响。据观察，小龙虾（Pacifastacus leniusculus）干扰砾石基质，可能促进沉积物的运输并影响生态群落。但是，人们对其中涉及的机制及其影响程度的理解不充分，尤其是与影响迁移性砾石层河的其他过程有关。一系列的水槽实验，在低流速下暴露于小龙虾活动6h的情况下，使用了狭窄分级的松散的，水处理的砾石床，与随后的较高流速相比，其夹带的谷粒数量大大增加。从未引入过哪种小龙虾的对照运行。小龙虾通过建造会影响前突的坑和土墩来改变其底物的地形。当行走和觅食时，它们还通过重新定向和改变表面颗粒的摩擦角来改变砾石的结构。在水加工的表面上，这种织物的重新排列显示出统计上显着的，部分的逆转，这种逆转是由先前的流动实现的。对于这些先前经过水处理的表面，小龙虾干扰引起的夹带增加在统计学上是显着的，其中gratransport几乎是其两倍。这表明，小龙虾是一种侵入性较广的入侵物种，在其北美西北部以外的温带地区，可以通过改变砾石河床的表面结构和降低表层谷物的稳定性来提高粗粒河床通量。这项研究进一步说明了在评估沉积物夹带力学和预测床荷通量的背景下，认识到流动生物调节河床的影响的重要性。

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