Invasive crayfish as drivers of fine sediment dynamics in rivers: field and laboratory evidence
Invasive crayfish as drivers of fine sediment dynamics in rivers: field and laboratory evidence
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DOI：
10.1002/esp.3486
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发表时间：
2014-02-01
影响因子：
3.3
通讯作者：
Macdonald, David W.
中科院分区：
文献类型：
--
作者：
Harvey, Gemma L.;Henshaw, Alexander James;Macdonald, David W.
尽管越来越多地认识到水生生物群作为地貌剂的潜力，但在微尺度细微沉积物动力学的生物驱动因素，特别是入侵物种的作用方面，仍然存在关键的知识空白。本研究通过室内和野外研究，在斑块尺度上探讨了入侵信号小龙虾对悬沙动力学的影响。提出并检验了三个假设：(1)信号小龙虾通过在流场中可检测到的洞穴和运动产生细小沉积物动员的脉冲；(2)在已知信号小龙虾最活跃的夜间时段，这种脉冲可能更频繁；以及(3)这些脉冲累积起来将足以驱动浑浊度的整体增加。通过室内中观实验，研究了粘土滩和粘土层基质两种处理对小龙虾悬沙浓度的影响。在野外研究中，研究了一条低地河流的高频近床和中流浊度时间序列，其中已知的信号小龙虾密度很高。实验室数据表明，信号小龙虾通过挖洞进入堤岸和细床物质，直接影响细颗粒沉积物脉冲的动员，并有证据表明夜间时段中点附近的活动水平增强。在现场条件下发现的类似的脉冲细沉积物动员模式遵循明显的夜间趋势，似乎能够推动环境浊度水平的增加。研究结果表明，信号小龙虾有可能影响悬浮泥沙产量，并对形态变化、物理栖息地质量以及营养物质和污染物的转移产生影响。考虑到信号小龙虾在整个欧洲的传播，以及它们在许多集水区以极高的密度存在，这一点尤其重要。需要进一步的以过程为基础的研究，以全面了解各种河流类型的影响。版权所有(C)2013 John Wiley&Sons，Ltd.
Despite increasing recognition of the potential of aquatic biota to act as geomorphic agents', key knowledge gaps exist in relation to biotic drivers of fine sediment dynamics at microscales and particularly the role of invasive species. This study explores the impacts of invasive signal crayfish on suspended sediment dynamics at the patch scale through laboratory and field study. Three hypotheses are presented and tested: (1) that signal crayfish generate pulses of fine sediment mobilisation through burrowing and movement that are detectable in the flow field; (2) that such pulses may be more frequent during nocturnal periods when signal crayfish are known to be most active; and (3) that cumulatively the pulses would be sufficient to drive an overall increase in turbidity. Laboratory mesocosm experiments were used to explore crayfish impacts on suspended sediment concentrations for two treatments: clay banks and clay bed substrate. For the field study, high frequency near-bed and mid-flow turbidity time series from a lowland river with known high densities of signal crayfish were examined. Laboratory data demonstrate the direct influence of signal crayfish on mobilisation of pulses of fine sediment through burrowing into banks and fine bed material, with evidence of enhanced activity levels around the mid-point of the nocturnal period. Similar patterns of pulsed fine sediment mobilisation identified under field conditions follow a clear nocturnal trend and appear capable of driving an increase in ambient turbidity levels. The findings indicate that signal crayfish have the potential to influence suspended sediment yields, with implications for morphological change, physical habitat quality and the transfer of nutrients and contaminants. This is particularly important given the spread of signal crayfish across Europe and their presence in extremely high densities in many catchments. Further process-based studies are required to develop a full understanding of impacts across a range of river styles. Copyright (c) 2013 John Wiley & Sons, Ltd.