• 关键词：城市  着生硅藻  性状  随机森林  胁迫-响应关系

• 基金项目：深圳市主要河流水生态监测与评价项目（No. 2019-07-233）

• 刘心怡
• 中国科学院水生生物研究所， 淡水生态与生物技术国家重点实验室， 武汉 430072;中国科学院大学， 北京 100049

• 刘婵
• 中国科学院水生生物研究所， 淡水生态与生物技术国家重点实验室， 武汉 430072;中国科学院大学， 北京 100049

• 敖偲成
• 中国科学院水生生物研究所， 淡水生态与生物技术国家重点实验室， 武汉 430072;中国科学院大学， 北京 100049

• 谭路
• 中国科学院水生生物研究所， 淡水生态与生物技术国家重点实验室， 武汉 430072

• 唐涛
• 中国科学院水生生物研究所， 淡水生态与生物技术国家重点实验室， 武汉 430072

• 摘要：着生藻类是河流生态系统的主要初级生产者， 了解城市化对着生藻类多样性的影响对于城市河流管理具有重要意义. 本研究以深圳市河流为例， 研究了河流着生硅藻性状及物种、功能多样性对城市干扰的响应. 研究发现城区和郊区的水质状况差异显著. 城区样点的NH₄⁺-N、NO₂-N、TN、TP和DOC浓度是郊区的3~20倍不等. 水环境的巨大变化也导致了河流着生藻类生物多样性的变化. 城区组物种丰富度、Pielou指数和Simpson指数均显著高于郊区组， 而功能均匀度则显著低于郊区组. 并且在21个硅藻性状中， 有15个性状在城区和郊区组间存在显著差异. 进一步用随机森林模型拟合着生藻类生物多样性与水质指标的关系， 结果发现硅藻性状对城市化反应较其他指标更为敏感. 特别是小型、可动、低共位群和运动群这4个性状指标， 构建的随机森林模型解释率能达到40%~60%， 而生物多样性指数构建的模型解释率只有15%~25%左右. 总体来说， TP和TN是影响城市河流着生硅藻多样性的主要水质指标. 在营养水平高的城市样点. 个体较大、能够移动的硅藻占有主导地位； 而在营养水平较低的郊区样点， 个体较小、有柄的低共位群硅藻更具优势. 我们的研究表明了硅藻性状在响应环境变化方面的敏感性， 硅藻性状是对河流生态状况进行评估的一项重要工具.

• Abstract：Benthic diatoms are the main primary producers in river ecosystems. Understanding the impact of urbanization on the diversity of benthic diatoms has an important significance for urban river ecological management. In this study， the response of the traits， taxonomic and functional diversity of river benthic algae to urban disturbance was assessed using the rivers in Shenzhen as an example. We found there were significant differences in water quality conditions between urban and suburban sample sites. The concentrations of NH₄⁺-N， NO₂-N， TN， TP， and DOC in the urban sample sites were 3~20 times higher than those in the suburban group. The dramatic changes in the water environment had also led to changes in the biodiversity of river benthic diatoms. The species richness， Pielou index， and Simpson index were significantly higher in the urban group than those in the suburban group， while the functional evenness was significantly lower than that in the suburban group. Among the 21 diatom traits， 15 traits were significantly different between urban and suburban groups. Random forest model was further used to fit the relationships between the biodiversity of the benthic diatoms and water quality indicators， and the responses of diatom traits to urbanization were found to be more sensitive than other indicators， especially the four traits of size2， mobile， low profile guild and motile guild， and the explanation rate of these constructed random forest model could reach 40%~60%， while the models constructed for the biodiversity indices explained only about 15%~25% of the variance. TP and TN were the main factors affecting benthic diatom diversity in urban rivers. In the urban sample sites with high nutrient content， diatoms with larger size and mobile were dominant， while in the suburban sample sites with lower nutrient content， smaller， stalked diatoms living in a smaller guild were more dominant. Our study demonstrates the sensitivity of diatom traits in response to environmental change， and diatom traits are an important tool for assessing the ecological status of rivers.

• Key words：urban  benthic diatoms  traits  random forest  stress-response relationships

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