珠江口鱼类群落功能多样性时空格局及其对环境因子的响应

The Pearl River Estuary is one of the most productive waters in the estuaries of China, which has important fishery economic position and ecological protection value. However, the ecosystem of the Pearl River Estuary has been confronted with serious environmental problems due to intensive human activities in recent years. As a result, fish diversity has declined sharply. The study of the diversity of functional traits can make a more accurate understanding of ecosystem functions and assess the impacts of environmental disturbance and stress on biodiversity, but the spatial-temporal pattern of fish functional diversity in the Pearl River Estuary and its response to environmental factors are still unclear. In this project, field investigations on fish communities and environmental factors at different periods (tides, seasons) and sites (eight outlets) will be conducted in the unique habitats of the Pearl River Estuary. Based on the field data, functional traits related to foraging, movement and habitat utilization of fish will be selected and measured, and then functional ecological approaches will be used to analyze the spatial-temporal pattern and dynamic changes of fish functional diversity in the Pearl River Estuary. We aim to reveal the interactions between fish species, functional traits and the environment, and to elucidate the responses of fish functional diversity to environmental factors. This project will promote the application of functional diversity methods and theories to the study of fish communities in the Pearl River Estuary. Furthermore, it will provide a scientific basis for the evaluation of the impacts of human activities on estuarine fish diversity and for the protection of estuarine fishes and ecosystems.

珠江口是我国河口中最富生产力的水域之一，具有重要的渔业经济地位和生态保护价值。近年来，由于高强度人类活动的干扰，珠江口生态系统面临严重的环境问题，鱼类多样性急剧衰退。利用功能性状的多样性研究可以更加准确的理解生态系统功能以及评估环境干扰和压力对生物多样性的影响。然而，珠江口鱼类群落功能多样性时空格局特征及其对环境因子的响应尚未明晰。本项目拟借助于珠江口独特的生境，通过对鱼类群落和环境因子时间（潮汐、季节）和空间（八大入海口）尺度的调查，选择和测定与鱼类觅食、运动和栖息地利用等相关的功能性状，采用功能生态学方法分析珠江口鱼类群落功能多样性时空格局和动态变化，揭示鱼类物种、功能性状与环境的相互作用关系，阐明鱼类群落功能多样性对环境因子的响应特征。研究结果将促进功能多样性方法和理论在珠江口鱼类群落研究中的应用，为评估人类活动对河口鱼类多样性的影响以及河口鱼类和生态系统的保护提供科学依据。

河口处于海洋和大陆交互作用最为活跃、剧烈的地带，生物多样性和资源丰富。然而，河口地区也是世界上人类活动最频繁、人口最稠密的地带之一，河口环境遭到高强度人类活动的干扰，生物多样性急剧丧失。本项目以珠江八大入海口鱼类为研究对象，通过野外调查鱼类群落和环境因子，并选取与食性类型和游泳能力等相关的鱼类形态功能特征，用功能生态学方法分析珠江口鱼类群落功能多样性的时空格局及其影响因素。研究发现：（1）珠江八大入海口鱼类多样性较高，本项目共调查到鱼类136种，隶属于16目59科。各生态类型均有分布，其中淡水洄游鱼类为群落优势类群，占渔获总生物量的33.49%，其次分别为降河洄游鱼类（23.44%）、淡水偶见鱼类（9.46%）、河口鱼类（8.39%）、溯河洄游鱼类（7.73%）、海洋洄游鱼类（7.30%）、海洋偶见鱼类（5.47%）以及海淡水无方向迁移鱼类（4.72%）。（2）鱼类群落功能多样性指数以及功能组成具有显著的季节差异，而各入海口空间差异不明显。与鱼类繁殖索饵等相关的季节节律以及水体理化环境因子的季节变动，改变了鱼类群落的种类和功能组成。（3）与物种多样性相比，功能多样性与环境因子相关性更高，表明功能多样性指数在评估群落响应环境变化和人类活动影响方面优于传统物种多样性。RLQ和第四角分析表明珠江口鱼类物种-功能性状-环境之间具有显著的相关关系，水体温度、盐度、总溶解固体、以及溶氧等是影响鱼类群落功能分布特征的主要环境因子。（4）尼罗罗非鱼和麦瑞加拉鲮等外来鱼类进入河口，成为优势种，对珠江口水域鱼类群落组成和功能多样性造成了较大的影响。以上结果揭示了理化环境因子和外来物种入侵是珠江口鱼类群落功能多样性时空格局形成的主导因子，为河口鱼类多样性保护提供了基础数据与理论支撑。我们建议在珠江河口鱼类和生态系统保护与管理中，将生境修复和外来物种控制作为首要策略。