四川黄龙钙华沉积区附生藻垫生物与水环境因子相关性分析

Analysis of epiphytic algal mats and the correlation with aquatic environmental factors in Huanglong travertine area, Sichuan

摘要:

【背景】近年来，四川省黄龙风景区钙华沉积地貌上藻垫大面积滋生，厚度达3-5 cm，严重影响了钙华的持续沉积及欣赏价值。【目的】为有效控制藻类过度生长，并提出相关治理方法措施，需要对藻垫的结构特征及滋生原因进行深入分析。【方法】利用PE-250高通量测序平台对黄龙钙华沉积区典型附生藻垫剖面的不同层次进行真核物种组成分析，同时通过场发射扫描电子显微镜对其微观形貌进行表征，并且对藻垫的生长厚度与水环境参数进行了相关性分析。【结果】藻垫内的真核生物有400种左右，优势藻类主要为硅藻门(Diatomea)、轮虫动物门(Rotifera)和链型植物门(Streptophyta)，硅藻门主要为桥弯藻属(Cymbella)。非度量多维尺度分析(non-metric multidimensional scaling, NMDS)统计和聚类分析表明，藻垫的中层和底层真核物种组成具有较高的相似性。场发射扫描电子显微镜的结果显示，硅藻主要分布在藻垫上层，中层主要为丝状藻类，底层为钙华颗粒填充在丝状藻构成的网状结构中。水质参数与藻垫生长的相关性分析表明，藻垫厚度主要与水体中的总氮(total nitrogen, TN)、总磷(total phosphorous, TP)和溶解氧(dissolved oxygen, DO)呈正相关(p<0.05)。【结论】黄龙钙华附生藻垫物种组成较为丰富，但在门水平上较为简单，具有物种组成及微观结构上的分层特性，水体营养化可能是促进藻垫生长的重要原因之一。本研究结果可为黄龙景区藻类滋生治理提供理论基础及依据。

Abstract:

[Background] In recent years, Huanglong travertine landscape has seen large-scale growth of algal mats with thickness of 3–5 cm, posing a threat to the travertine deposition and affecting the ornamental value of the landscape. [Objective] To dissect the structure of the algal mats and the reasons for the large-scale growth, thereby to control the growth of algae, and to propose management methods. [Methods] The composition of eukaryotic species in different layers of typical epiphytic algal mats in the Huanglong travertine area was analyzed based on PE-250. Their morphology was characterized via the field emission scanning electron microscope, and the correlation between the thickness of algal mats and water environment parameters was examined. [Results] The algal mats were home to about 400 species of eukaryotes, with the dominant algae of Diatomea (mainly Cymbella), Rotifera, and Streptophyta. Non-metric multidimensional scaling (NMDS) analysis and clustering analysis showed that the composition of eukaryotic species in the middle layer of the algal mats was highly similar to that in the lower layer. Diatoms dominated the upper layer, and the middle layer was mainly composed of filamentous algae. For the lower layer, travertine particles were seen in the reticular structure composed of filamentous algae. The thickness of algal mats was mainly in positive correlation with the total nitrogen (TN), total phosphorus (TP), and dissolved oxygen (DO) in the water (p<0.05). [Conclusion] The algal mats boast abundant species in a few phyla. The three layers of the mat are distinct from each other in species composition and microstructure and water eutrophication can explain the rapid growth of algal mats. This study lays a theoretical basis for the management of algal blooms in Huanglong Scenic and Historic Interest Area.