东江浮游藻类群落对生境响应关系研究

The project, to be conducted in Dongjiang River Basin, is aiming for revealing the responses of planktonic algae to their river habitat parameters and using the planktonic algae features as a possible tool in evaluating the ecologically healthy states of a river. To better understand the characteristics of planktonic algae in the main stream and several cardinal tributaries in Dongjiang River, the project will study the spatial and temporal patterns and the inter- and intra-annual fluctuation of the planktonic algae community features, particularly the biomass (chlorophyll a concentration), the species composition and the cell density of some concerned species or taxa groups. The research methods and approaches needed in this study include field survey, sample collection and laboratory analysis, combined with 3S and statistic analyses. Through analyzing the relationships between the biological indexes of planktonic algae and the habitat parameters both quantitatively and qualitatively, the study may reveal the features of planktonic algae communities and even trace some of the features back to certain particular habitat characteristics and the intensitiy of human impacts, and thus realize how and in which extent these indices of planktonic algae community respond to different habitat parameters. In addition, the study will also examine, according to the landscape ecology theory, the scale effect, with which the biomass, the biodiversity indices and the cell density of certain species or taxa groups respond to water quality..In terms of applying the expected research results to river ecological conservation, this study will also try to test the possibility and availability of planktonic algae features in evaluating the ecologically healthy states of a river. For this purpose, the study will compare the features of planktonic algae community in riversd with that in lakes, and identify the relationships between the biological indices of planktonic algae community and the habitat parameters characterized with a monotonic function.

本项目以东江及主要支流为研究区域，在基础理论方面，通过野外取样、观测和室内样品分析，综合运用3S技术、定量统计和定性分析方法，研究浮游藻类生物量（叶绿素含量）、优势种组成特征、特征类群细胞密度等，揭示其年际、年内变化规律和空间分布格局；通过分析不同生境类型中浮游藻类特征的稳定性，建立不同生境参数与各类浮游藻类生物学指标的定量与定性关系，明确浮游藻类群落特征对这些生境参数以及人类活动影响强度的响应方式和响应程度，依据景观生态学理论，检验浮游藻类的生物量、多样性指数、特征类群细胞密度等特征对水质参数响应的空间尺度效应。.在应用方面，本研究将筛选对生境特征梯度变化有单调响应关系的相关指标，探索浮游藻类指标在河流生态系统健康评价中的有效性，为河流生态系统健康评价与东江河流生态系统保护提供科学依据。

本研究通过野外调查和现场取样分析，开展了东江河流浮游生物与生境关系研究，并探讨了应用浮游生物特征对河流生态健康状态评价的可能性。课题的主要研究结论如下：（1）有机污染和营养物指标浓度的季节差异不显著，但其在城镇用地和林地主导的集水区之间空间差异显著；（2）低级序河流的水质受土地利用配置指标的影响最强烈。山区耕地、园地和草地的斑块密度越高，平原城镇用地的最大斑块指数越高，水质越差。与河岸带或河段尺度相比，集水区尺度土地利用能更好地解释低级序河流水质整体差异，但土地利用对水质影响的多尺度特征也取决于所选择的水质指标和地貌状况；（3）根据对浮游藻类群落进行的TWINSPAN分析，可将流域样点的群落分为7个不同组群，不同组群的空间异质性主要体现了流域环境污染梯度和生境差异特征，CCA分析表明溶解氧（DO）、总氮（TN）、电导率（EC）、海拔（Ele）是影响东江流域河流浮游藻类群落结构组成和分布的重要因子；（4）运用水质生物学方法对东江流域河流水质状况进行了评价，并分析了评价指数的适用性。研究表明污生指数（SI）、功能类群评价指数（Q）、南美大草原硅藻指数指数(The Pampean Diatom Index, IDP)以及硅藻营养化指数(Trophic Diatom Index, TDI)均为东江流域河流水质适用的评价指数，但各指数评价结果等级与我国现有的水质等级评价结果并不完全一致。