Monthly sampling reveals seasonal fine sediment fluctuations and riverine invertebrate community responses.
Monthly sampling reveals seasonal fine sediment fluctuations and riverine invertebrate community responses.
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每月采样揭示了季节性细沉积物波动和河流无脊椎动物群落的反应。
DOI：
10.1016/j.scitotenv.2023.168750
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发表时间：
2024
期刊：
影响因子：
--
通讯作者：
Davis NG
中科院分区：
文献类型：
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作者：
Davis NG
管理湖泊生态系统中沉积细泥沙含量的影响，需要了解流域土地利用的变化如何改变河流的自然沉积物状况（侵蚀，运输，沉积）。不幸的是，没有现有的研究采用了适当的采样频率在一段时间内涵盖了整个范围的季节性流动条件，预计影响流沉积物动力学。我们确定了短期（每月）动态沉积细泥沙和无脊椎动物群落超过12个月，在15个第四和第五阶河流排水流域的低，中，高土地利用强度在新西兰南部地区，以确定何时何地细泥沙威胁流健康。我们比较了Question再悬浮法（可悬浮无机沉积物，SIS）和流中可见沉积物覆盖评估方法，并评估了四种常用的无脊椎动物流健康指标对新开发的沉积物的有效性。SIS的月变化在所有土地利用类别中都很大，但随着土地利用强度的增加而变得更加明显。所有15个站点都经历了一段较长时间的相对稳定的流量，这与15个站点中14个站点的SIS的最大短期增加相吻合。然而，SIS的变异性并没有反映在大型无脊椎动物的指标。这些研究结果表明，控制细泥沙输入河流和溪流将是最有效的目标时，在长期稳定的流量，特别是在高土地利用强度集水区。再悬浮法始终优于视觉估计时，考虑到其与大型无脊椎动物指标的关系，而沉积物的具体指标表现出更强的关联细沉积物比常用的指标，例如（%EPT）。我们的结论是，恢复/缓解措施不能仅仅基于短期，甚至是长期的，减少细泥沙，或单独的物理措施，但应基于长期恢复的沉积物影响的无脊椎动物群落，同时测量生物和非生物条件。
Managing the impacts of anthropogenically enhanced deposited fine sediment levels in lotic ecosystems requires understanding of how catchment land-use changes have altered the natural sediment regime (erosion, transport, deposition) of rivers. Unfortunately, no existing studies have employed an appropriate sampling frequency over a period encompassing the full range of seasonal flow conditions expected to influence in-stream sediment dynamics. We determined the short-term (monthly) dynamics of deposited fine sediment and invertebrate communities over 12-months in 15 fourth- and fifth-order rivers draining catchments of low, medium and high land-use intensity in Southland, New Zealand to determine when and where fine sediment threatens stream health. We compared the Quorer resuspension method (suspendable inorganic sediment, SIS) and the in-stream visual sediment cover assessment method, and evaluated the effectiveness of four commonly-used invertebrate stream health metrics against their newly developed sediment-specific counterparts. Monthly variability in SIS was substantial across all land-use categories, but became more pronounced as land-use intensity increased. All 15 sites experienced a prolonged period of relatively stable flow which coincided with the largest short-term increase in SIS at 14 of the 15 sites. However, variability in SIS was not mirrored in macroinvertebrate metrics. These findings suggest that controlling inputs of fine sediment to rivers and streams will be most effective when targeted at periods of prolonged stable flow, particularly within high land-use intensity catchments. The resuspension method consistently outperformed visual estimates when considering its relationship with macroinvertebrate metrics, while sediment-specific metrics demonstrated a stronger association with fine sediment than commonly employed metrics e.g. (%EPT). We conclude that restoration/mitigation practices cannot be based solely on short-term, or even long-term, reductions in fine sediment, or on physical measures alone, but should be based on long-term recoveries of sediment-impacted invertebrate communities using concurrent measurements of both biotic and abiotic conditions.