拟柱孢藻(Cylindrospermopsis raciborskii)生态学研究现状与面临的挑战

State of the art and challenges of Cylindrospermopsis raciborskii ecology

拟柱孢藻(Cylindrospermopsis raciborskii)广泛分布于热带地区,被认为是热带或泛热带种类,能够产生多种毒素,其在水体中形成优势或发生水华将直接影响供水安全并导致生态系统的退化。近30年来,拟柱孢藻的分布在全球尺度上呈“蔓延”之势,在欧洲、北美洲和亚洲大陆的很多水体中广泛发生。我国近10年来拟柱孢藻分布的范围不断扩大,在珠江下游地区的供水水库中成为最主要的优势蓝藻种类。按目前的发展趋势,预计拟柱孢藻将很快成为我国淡水水体中继微囊藻(Microcystis)之后的第2个管控有害蓝藻种类。为避免发生类似于被动应对大范围微囊藻重度水华的困局,迫切需要前瞻性地开展基于现代生态学理念的拟柱孢藻种群生态学研究,理解其快速大范围发生并占据优势的生态学基础。本文从生物地理学与种群生态学的角度,对当前拟柱孢藻的扩张机制、种群竞争优势及其对生态系统的影响进行梳理,重点分析了拟柱孢藻对磷的高效吸收机制与对热带水环境的适应性,强调认为珠江流域及邻近地区是东亚和全球尺度上拟柱孢藻研究的关键区域。我们认为在气候变暖的背景下,珠江流域及邻近地区将成为该种北向扩散的种源区,以云贵高原为跳板,进入长江流域进一步向高纬度扩散。制定国家层面上的监测规范、防治方法和管理对策,迫切需要实施跨学科的整合研究,大力推进我国拟柱孢藻种群生态学的研究和发展。

Cylindrospermopsis raciborskii is widely distributed in the tropics and is considered to be a tropical or pantropical species capable of producing multiple toxins.In the last three decades,the distribution of the species has shown a strong trend of“spreading”on a global scale,and it has been widely occurring in many water bodies in Europe,North America and Asia.Nowadays,the species has been widely found in China,and is abundant in many lakes and reservoirs,especially in those for drinking water supply in southern China.It has been reducing water supply safety and largely impaired aquatic ecosystem health.In the lowland reservoirs of the Pearl River basin,the species has become the most dominant cyanobacterial species.It is predicted that C.raciborskii will become the second most harmful cyanobacteria species in China's fresh water after Microcystis spp.In order to avoid the dilemma similar to passive response to heavy Microcystis blooms in the country scale,it is required to carry out a prospective ecological study based on modern ecological concepts,and to understand the biological and ecological basis of its rapid and large-scale occurrence and dominance.In this review,the expansion mechanism,competitive advantage at population level and its impact on aquatic ecosystems were commented from the perspective of biogeography and population ecology.We summerised phosphorus uptake mechanisms by the species and its adaptability to tropical aquatic environment.Under global climate warming,the Pearl River Basin and its adjacent areas will function as the“seed”source area for the species to diffuse northward.The species will take advantage of the Yunnan-Guizhou Plateau as a stepping-stone to enter the Yangtze River basin and further spread to higher latitudes.So,we emphasize that the Pearl River Basin and its adjacent areas are the critical area for the study of C.raciborskii in both East Asia and the global scale.We strongly suggest to carry out interdisciplinary approaches to the ecology of C.raciborskii for formulating national monitoring programs,controlling methods and management strategies.