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化学物质对浮游植物的抑制作用被认为是促进浅湖清澈水状态稳定的机制之一。尽管大量研究表明植物提取物对浮游植物有抑制作用，但这一过程在生态系统水平上的相关性仍存在争议。原位证据很难获得，一些重要的细节化感相互作用是未知的。本项目旨在利用透析袋实验，在一个小湖泊中，为已知含有化感活性物质的大型植物狐尾藻（Myriophyllum verticillatum）对浮游植物的化感作用提供原位证据。将进行实地和实验室实验，以测试特定的藻类相关细菌是否代谢化感物质，从而导致所观察到的藻类物种的不同敏感性。多酚是一种常见的化感化学物质，将利用荧光染色流式细胞术研究不同藻类中多酚的新作用模式。将利用PAM荧光法和流式细胞术对verticillatum中纯化的化合物进行化学鉴定，并对其对浮游植物的影响进行测试。我们期望在水生环境中对神经相互作用的理解做出重大贡献。

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.