Allelopathic effects of submerged macrophytes on phytoplankton: In situ evidence, bacterial influence and new modes of action

沉水植物释放的化感物质对浮游植物的抑制被认为是有助于稳定浅水湖泊清水状态的机制之一。尽管许多研究表明植物提取物对浮游植物具有抑制作用，但这一过程在生态系统水平上的相关性仍存在争议。很难获得现场证据，化感作用的一些重要细节尚不清楚。这项拟议的项目旨在通过在一个小湖中进行透析袋实验，提供大型植物物种Myriophyllum verticillata对浮游植物的化感作用的现场证据，该物种已知含有化感活性物质。将进行现场和实验室实验，以测试特定的藻类相关细菌是否代谢化感物质，从而有助于观察到的藻类物种的区分敏感性。多酚是一类常见的化感物质，将利用荧光染料染色的流式细胞术研究不同藻类的新作用模式。从黄曲霉中提纯的化合物将进行化学鉴定，并使用PAM荧光法和流式细胞术测试其对浮游植物的影响。我们期待着对理解水环境中的变态相互作用做出重大贡献。

Inhibition of phytoplankton by allelochemicals released by submerged macrophytes is thought to be one of the mechanisms that contribute to the stabilisation of clear-water states in shallow lakes. Despite numerous studies showing the inhibiting effect of plant extracts on phytoplankton, the relevance of this process at ecosystem level is still debated. In situ evidence is difficult to achieve and a number of important details of allelopathic interactions are unknown. The proposed project aims to provide in situ evidence of alielopathic effects of the macrophyte species Myriophyllum verticillatum, which is known to contain allelopathically active substances, on phytoplankton using dialysis bag experiments in a small lake. Field and laboratory experiments will be carried out to test whether specific algae-associated bacteria metabolise allelochemicals and thus contribute to the observed differential sensitivity of algal species. New modes of action of polyphenols, a common group of allelochemicals, will be investigated in different algae species using fluorescent dye staining flow cytometry. Purified compounds from M. verticillatum will be chemically identified and their effects on phytoplankton tested using PAM fluorometry and flow cytometry. We expect a significant contribution to the understanding of alielopathic interactions in the aquatic environment.