State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China.
Sci Total Environ. 2019 Feb 1;649:201-211. doi: 10.1016/j.scitotenv.2018.08.308. Epub 2018 Aug 24.
Flow and sediment co-create habitat structure and dynamics within river and lake systems, of which the ecological effects are well-documented. But the temporal variability of aquatic community response to continuous flow-sediment alterations is less well-known. This paper explored aquatic biota response to the flow-sediment regime in a broader temporal context using long-term paired hydrological database and monitoring data of benthic invertebrates in Dongting Lake. The inter-annual variations of benthic invertebrates and certain flow and sediment variables were synchronous. Community diversity parameters showed different response to different hydrological events and particularly revealed a short-term peak in the first two years after the operation of the Three Gorges Dam. This finding affirmed the importance of the time series study. The overall flow-sediment regime, calculated from 15 flow and sediment characteristics, affected community structures and could also affect benthic invertebrates by affecting the water quality. The combination of variables, including sediment inputs load, sediment exports/inputs ratio and the duration of low water level, could best explain the variation of benthic invertebrate assemblages and should be given the greatest management concern. When individual components of the flow-sediment regime were analysed, the response patterns of community parameters to different environmental variables or to different gradients of the same variables were complex. Our results suggest that the sediment seemed to be a more influential stressor than flow, especially erosion, which could significantly reduce total abundance and species richness. The effect of the flow regime was reflected by the duration of the low water level. Stressor gradients and the response patterns of different taxa to different stressors should be considered by river and lake managers. The results would provide valuable information for the design of lake management strategies and upstream reservoir regulation rules.
水流和泥沙共同塑造了河流和湖泊系统中的生境结构和动态，其生态影响已得到充分证明。但是，水生生物群落对连续水流泥沙变化的响应的时间变化性还不太为人所知。本文通过使用洞庭湖长期配对水文数据库和底栖无脊椎动物监测数据，在更广泛的时间背景下探讨了水生物种对水流泥沙状况的响应。底栖无脊椎动物和某些水流泥沙变量的年际变化是同步的。群落多样性参数对不同的水文事件表现出不同的响应，特别是在三峡工程运行后的前两年，出现了短期峰值。这一发现证实了时间序列研究的重要性。从 15 个水流和泥沙特征计算得出的整体水流泥沙状况影响了群落结构，也可以通过影响水质来影响底栖无脊椎动物。包括泥沙输入负荷、泥沙输出/输入比和低水位持续时间在内的变量组合可以最好地解释底栖无脊椎动物组合的变化，应给予最大的管理关注。当分析水流泥沙状况的各个组成部分时，群落参数对不同环境变量或同一变量的不同梯度的响应模式是复杂的。我们的结果表明，泥沙似乎比水流更具影响力，尤其是侵蚀作用，它可以显著降低总丰度和物种丰富度。水流状况的影响反映在低水位的持续时间上。河流和湖泊管理者应考虑胁迫梯度以及不同类群对不同胁迫的响应模式。研究结果将为湖泊管理策略的设计和上游水库调节规则提供有价值的信息。
