西藏扎布耶盐碱湖真核浮游生物的群落结构与多样性分析

Community structure and diversity of eukaryotic plankton in the Zabuye saline-alkali Lake, Xizang

摘要:

【背景】西藏扎布耶盐碱湖(Zabuye saline-alkali Lake, ZL)是以水体富含高浓度CO₃²⁻、HCO₃⁻和Na⁺为显著特性的盐碱湖，涉及真核浮游生物多样性的相关研究尚未深入。【目的】系统探究扎布耶盐碱湖真核浮游生物的多样性，明确真核浮游生物的群落结构组成和真菌的营养方式。【方法】采用18S rRNA基因序列(V5−V7区)高通量测序分析扎布耶盐碱湖真核浮游生物的群落结构组成和物种多样性；基于盐碱湖水化学特征和Spearman相关系数分析属类群与环境因子的相关性，并使用FUNGuild数据库预测真菌的营养方式。【结果】Illumina测序获得真核浮游生物共计两界(原生动物界和真菌界) 12门20纲25属。优势真核浮游生物门类群依次是Aphelidea (0.12%−51.84%)、Nucleariidae-Fonticula超类群(0%−91.70%)、子囊菌门(Ascomycota, 1.38%−9.04%)和担子菌门(Basidiomycota, 0.20%−10.16%)。常见属(相对丰度≥1%)主要有Nuclearia(0%−91.70%)、镰孢菌属(Fusarium, 1.38%−4.32%)、Paraphelidium(0%−4.57%)和纤毛虫属(Homalogastra, 0%−4.39%)。纤毛虫属、Protosporangium和Nuclearia与Na⁺、K⁺、Ca²⁺等离子浓度及总盐度呈极显著正相关，与温度(T)、总磷(TP)、总有机碳(TOC)和pH呈极显著负相关。各样本中浮游真菌的功能大多数未知，并且均存在腐生营养型真菌(saprotroph, 1.38%−5.24%)。【结论】扎布耶盐碱湖真核浮游生物群落结构与其他地区盐碱湖相似，即优势门是子囊菌门和担子菌门，但是存在Aphelidea和Nucleariidae-Fonticula超类群等特殊的优势门类群；群落结构与扎布耶盐碱湖的离子特征参数密切相关；浮游真菌的主要营养类型是腐生营养型。

Abstract:

[Background] Zabuye Lake (ZL) is a saline-alkali lake in Xizang, with high concentrations of CO₃²⁻, HCO₃⁻, and Na⁺. There are few studies involving eukaryotic plankton diversity in this lake. [Objective] To clarify the diversity and composition of eukaryotic plankton and the trophic mode of fungi in ZL. [Methods] High-throughput sequencing of the V5–V7 region of the 18S rRNA gene was employed to analyze the community structure and species diversity of eukaryotic plankton in ZL. Spearman correlation coefficients were calculated to measure the correlations of genera with the chemical characteristics of lake water. FUNGuild was used to predict the trophic mode of fungi. [Results] Illumina sequencing yielded 25 genera of eukaryotic plankton belonging to 20 classes, 12 phyla, and 2 kingdoms. The dominant phyla were Aphelidea (0.12%−51.84%), Nucleariidae-Fonticula (0%−91.70%), Ascomycota (1.38%−9.04%), and Basidiomycota (0.20%−10.16%). The common genera included Nuclearia (0%−91.70%), Fusarium (1.38%−4.32%), Paraphelidium (0%−4.57%) and Homalogastra (0%−4.39%). Homalogastra, Protosporangium and Nuclearia showed significantly positive correlations with Na⁺, K⁺, and Ca²⁺ concentrations and total salinity, and they had significantly negative correlations with temperature, total phosphorus, total organic carbon, and pH. The functions of planktonic fungi in each sample site were mostly unknown and saprotrophic fungi (1.38%−5.24%) were present in all the sample sites. [Conclusion] The community structure of eukaryotic plankton in ZL was similar to that in other saline-alkali lakes. The dominant phyla were Ascomycetes and Basidiomycota, with the presence of Aphelidea and Nucleariidae-Fonticula. The community structure was closely related to the salt concentrations of ZL. Most of the planktonic fungi in this lake were saprotrophs.