绿藻群体形成及其影响因子研究进展

Research Progress on Colony Formation of Green Algae and Influencing Factors

作为淡水生态系统浮游植物的重要组成部分,绿藻是很多动物的开口饵料,其群体形成是应对外界环境压力的一种诱导型防御策略,当环境压力不存在时,会恢复单细胞形态。总结了影响绿藻单细胞-群体形态转变的外源因子及种间作用机制,包括非生物因子(营养、光照、温度)、生物因子(植食性浮游动物摄食、藻-藻竞争、沉水植物-藻竞争)以及人类活动对水生态系统的潜在压力,外源因子(低温、种间信息物质)诱导的多糖积累及胞外多糖分泌增加,可能是诱导绿藻群体聚集的重要原因;而人类活动造成的气候变暖、UVB辐射增强、微污染物增加(重金属、除草剂等),可能会打破绿藻由单细胞向群体形态的转换,提高绿藻被小型草食性动物摄食的概率,影响水生态系统的信息流,从而引发食物网级联效应,进而影响生态系统功能。基于已有的相关研究,总结了绿藻群体形成对于水生态系统结构、藻类毒理学以及微藻收获的重要意义与研究价值。

Green algae are an important component of the phytoplankton community in freshwater ecosystems, and a favored food for many herbivores. However, green algae are not defenseless to predation. Numerous studies have shown that colony formation of green algae is an inducible defense for coping with environmental stress and, when the stressor is removed, single-cell morphology is restored. This article reviews the exogenous factors and interspecific interaction mechanism that affect the morphological transition of green algae from single cells to colonies, discusses the formation mechanism of algae colonies and identifies potential applications. Our aim was to provide a reference for predicting phytoplankton community structure in freshwater ecosystems and for harvesting microalgae on a large scale. Abiotic factors included nutrition, light and temperature, and biological factors included herbivorous zooplankton predation, competition between algae species, macrophyte-algae competition. The affecting factors also include potential threats to aquatic ecosystems caused by human activities. It has been suggested that increased polysaccharide accumulation and secretion might be the primary mechanism inducing algal cell aggregation. Climate warming, UVB irradiation and trace pollutants(heavy metals, herbicides, etc.) could interrupt the transformation from single-cell to colony in green algae and increase algal predation by small herbivorous animals,consequently influencing infochemical flow in the food web and perhaps even ecosystem function. Finally,based on existing research, we summarize the ecological significance and research value of colony formation in green algae, such as shaping phytoplankton structure, algal toxicology, and the industrial harvest of microalgae.