附石生物营养质量对干旱胁迫的响应及机制  

Response Mechanism and Nutritional Quality in Epilithon under Drought Stress

作　　者：李唤唤 谭香[2,3] 张全发 LI Huan-huan;TAN Xiang;ZHANG Quan-fa(School of Ecology and Environment,Tibet University,Lhasa 850000,P.R.China;Key Laboratory of Aquatic Botany and Watershed Ecology,Wuhan Botanical Garden,Chinese Academy of Sciences,Wuhan 430074,P.R.China;Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station,the Chinese Academy of Sciences&Hubei Province,Wuhan 430074,P.R.China)

机构地区：[1]西藏大学生态环境学院,西藏拉萨850000 [2]中国科学院武汉植物园水生植物与流域生态重点实验室,湖北武汉430074 [3]中国科学院&湖北省丹江口湿地生态系统野外科学观测研究站,湖北武汉430074

出　　处：《水生态学杂志》2024年第3期21-31,共11页Journal of Hydroecology

基　　金：国家自然科学基金项目(32271665、32030069)。

摘　　要：探讨河流附石生物营养质量对干旱的响应及机制,为河流生物膜研究和对全球气候变暖大背景下的脆弱水域保护提供科学支持。基于脂肪酸和化学计量学2种食物营养质量指示方法,利用中宇宙控制实验模拟野外干旱情景,研究了干旱对附石生物营养质量的影响,并从宏观的附石生物膜藻类群落结构和微观的宏基因组技术2个层面探索其影响机制。结果表明,干旱后多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)中的二十二碳六烯酸(docosahexaenoic acid,DHA)和二十碳五烯酸(eicosapentaenoic acid,EPA)等含量减少;附石生物中磷(P)含量显著减少(P<0.05),C/P、N/P增加。硅藻是附石生物膜中的优势类群,优质脂肪酸的生产者,富含EPA、DHA,干旱后硅藻密度和丰度显著减少(P<0.05)。基于宏基因组分析结果,附石生物脂质代谢通路中脂肪酸生物合成显著减少(P<0.05),脂肪酸降解显著增加(P<0.05),进而影响EPA、DHA的含量。干旱导致河流生态系统基础资源营养质量下降,进而可能对整个河流生态系统中消费者的生长和繁殖产生影响。研究结果从基础资源碳质量新视角为水生态系统食物网的碳源及传递研究提供了重要依据。Against the backdrop of global warming,droughts are happening more often.The epilithon is crucial to primary production in river ecosystems,forms the cornerstone of material circulation in the food web,and provides carbon source for higher-level consumers.The decline in water area during droughts inevitably affects the epilithon habitat.Yet,the impact of drought on the nutritional quality of epilithon remains largely unexplored.In this study,we assessed the impact of drought on nutritional quality by conducting a mesocosm manipulation experiment,focusing on stoichiometry and polyunsaturated fatty acids(PUFA),particularly eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA).The response and mechanism of nutritional quality in epilithon was then analyzed in terms of the content and composition of fatty acids,algae community structure,ecological stoichiometry,and microbial community using metagenomic sequencing.The mesocosm manipulation experiment included a drought treatment group and a control group and was run in triplicate.After preculturing for two weeks,an extreme drought was simulated in the treatment mesocosm,while water circulation was maintained in the control group.Epilithon samples were collected on day 0,7 and 14 of the experiment for analysis of nutritional quality.This study not only affirmed the observed influence of drought on the nutritional quality of epilithon but also delved into the underlying mechanism by examining community composition and function of epilithon.The findings revealed a significant reduction in DHA and EPA content in epilithon in the drought treatment group.The phosphorus(P)content decreased significantly(P<0.05),resulting in an increase in the C/P and N/P ratios.Diatoms,the predominant epilithon group,rich in EPA and DHA,exhibited a significant decline in density and abundance after the drought(P<0.05).Additionally,metagenomic analysis revealed a significant reduction in fatty acid biosynthesis within the lipid metabolic pathway of epilithon(P<0.05),accompanied by a notable

关 键 词：干旱胁迫 附石生物 脂肪酸 营养质量 宏基因组 

分 类 号：X171.1[环境科学与工程—环境科学] Q178.1[生物学—水生生物学]